Procedure

1. Create a new playbook.yml file with the following content:

   - hosts: all
     vars:
       storage_safe_mode: false
       storage_volumes:
         - name: data
           type: raid
           disks: [sdd, sde, sdf, sdg]
           raid_level: raid0
           raid_chunk_size: 32 KiB
           mount_point: /mnt/data
           state: present
     roles:
       - name: rhel-system-roles.storage

   Warning

   Device names can change in certain circumstances; for example, when you add a new disk to a system. Therefore, to prevent data loss, we do not recommend using specific disk names in the playbook.

2. Optional. Verify playbook syntax.

   # ansible-playbook --syntax-check playbook.yml

3. Run the playbook on your inventory file:

   # ansible-playbook -i inventory.file /path/to/file/playbook.yml

Procedure

1. Create a new playbook.yml file with the following content:

   - hosts: all
     vars:
       storage_safe_mode: false
       storage_pools:
         - name: my_pool
           type: lvm
           disks: [sdh, sdi]
           raid_level: raid1
           volumes:
             - name: my_pool
               size: "1 GiB"
               mount_point: "/mnt/app/shared"
               fs_type: xfs
               state: present
     roles:
       - name: rhel-system-roles.storage

   Note

   To create an LVM pool with RAID, you must specify the RAID type using the raid_level parameter.

2. Optional. Verify playbook syntax.

   # ansible-playbook --syntax-check playbook.yml

3. Run the playbook on your inventory file:

   # ansible-playbook -i inventory.file /path/to/file/playbook.yml

Procedure

1. Create a new playbook.yml file with the following content:

   - hosts: all
     vars:
       storage_volumes:
         - name: barefs
           type: disk
           disks:
            - sdb
           fs_type: xfs
           fs_label: label-name
           mount_point: /mnt/data
           encryption: true
           encryption_password: your-password
     roles:
      - rhel-system-roles.storage

2. Optional: Verify playbook syntax:

   # ansible-playbook --syntax-check playbook.yml

3. Run the playbook on your inventory file:

   # ansible-playbook -i inventory.file /path/to/file/playbook.yml

Procedure

1. Start the interactive parted shell:

   # parted block-device

2. Determine if there already is a partition table on the device:

   # (parted) print

   If the device already contains partitions, they will be deleted in the following steps.

3. Create the new partition table:

   # (parted) mklabel table-type

   • Replace table-type with with the intended partition table type:

     • msdos for MBR
     • gpt for GPT

   Example 4.1. Creating a GUID Partition Table (GPT) table

   To create a GPT table on the disk, use:

   # (parted) mklabel gpt

   The changes start applying after you enter this command.

4. View the partition table to confirm that it is created:

   # (parted) print

5. Exit the parted shell:

   # (parted) quit

Procedure

1. Start the parted utility. For example, the following output lists the device /dev/sda:

   # parted /dev/sda

2. View the partition table:

   # (parted) print
   
   Model: ATA SAMSUNG MZNLN256 (scsi)
   Disk /dev/sda: 256GB
   Sector size (logical/physical): 512B/512B
   Partition Table: msdos
   Disk Flags:
   
   Number  Start   End     Size    Type      File system  Flags
    1      1049kB  269MB   268MB   primary   xfs          boot
    2      269MB   34.6GB  34.4GB  primary
    3      34.6GB  45.4GB  10.7GB  primary
    4      45.4GB  256GB   211GB   extended
    5      45.4GB  256GB   211GB   logical

3. Optional: Switch to the device you want to examine next:

   # (parted) select block-device

Procedure

1. Start the parted utility:

   # parted block-device

2. View the current partition table to determine if there is enough free space:

   # (parted) print

   • Resize the partition in case there is not enough free space.

   • From the partition table, determine:

     • The start and end points of the new partition.
     • On MBR, what partition type it should be.

3. Create the new partition:

   # (parted) mkpart part-type name fs-type start end

   • Replace part-type with with primary, logical, or extended. This applies only to the MBR partition table.
   • Replace name with an arbitrary partition name. This is required for GPT partition tables.
   • Replace fs-type with xfs, ext2, ext3, ext4, fat16, fat32, hfs, hfs+, linux-swap, ntfs, or reiserfs. The fs-type parameter is optional. Note that the parted utility does not create the file system on the partition.
   • Replace start and end with the sizes that determine the starting and ending points of the partition, counting from the beginning of the disk. You can use size suffixes, such as 512MiB, 20GiB, or 1.5TiB. The default size is in megabytes.

   Example 4.2. Creating a small primary partition

   To create a primary partition from 1024MiB until 2048MiB on an MBR table, use:

   # (parted) mkpart primary 1024MiB 2048MiB

   The changes start applying after you enter the command.

4. View the partition table to confirm that the created partition is in the partition table with the correct partition type, file system type, and size:

   # (parted) print

5. Exit the parted shell:

   # (parted) quit

6. Register the new device node:

   # udevadm settle

7. Verify that the kernel recognizes the new partition:

   # cat /proc/partitions

Procedure

1. Start the interactive fdisk shell:

   # fdisk block-device

2. View the current partition table to determine the minor partition number:

   Command (m for help): print

   You can see the current partition type in the Type column and its corresponding type ID in the Id column.

3. Enter the partition type command and select a partition using its minor number:

   Command (m for help): type
   Partition number (1,2,3 default 3): 2

4. Optional: View the list in hexadecimal codes:

   Hex code (type L to list all codes): L

5. Set the partition type:

   Hex code (type L to list all codes): 8e

6. Write your changes and exit the fdisk shell:

   Command (m for help): write
   The partition table has been altered.
   Syncing disks.

7. Verify your changes:

   # fdisk --list block-device

Procedure

1. Start the parted utility:

   # parted block-device

2. View the current partition table:

   # (parted) print

   From the partition table, determine:

   • The minor number of the partition.
   • The location of the existing partition and its new ending point after resizing.

3. Resize the partition:

   # (parted) resizepart 1 2GiB

   • Replace 1 with the minor number of the partition that you are resizing.
   • Replace 2 with the size that determines the new ending point of the resized partition, counting from the beginning of the disk. You can use size suffixes, such as 512MiB, 20GiB, or 1.5TiB. The default size is in megabytes.

4. View the partition table to confirm that the resized partition is in the partition table with the correct size:

   # (parted) print

5. Exit the parted shell:

   # (parted) quit

6. Verify that the kernel registers the new partition:

   # cat /proc/partitions

7. Optional: If you extended the partition, extend the file system on it as well.

Procedure

1. Start the interactive parted shell:

   # parted block-device

2. View the current partition table to determine the minor number of the partition to remove:

   # (parted) print

3. Remove the partition:

   # (parted) rm minor-number

   • Replace minor-number with the minor number of the partition you want to remove.

   The changes start applying as soon as you enter this command.

4. Verify that you have removed the partition from the partition table:

   # (parted) print

5. Exit the parted shell:

   # (parted) quit

6. Verify that the kernel registers that the partition is removed:

   # cat /proc/partitions

7. Remove the partition from the /etc/fstab file, if it is present. Find the line that declares the removed partition, and remove it from the file.

8. Regenerate mount units so that your system registers the new /etc/fstab configuration:

   # systemctl daemon-reload

9. If you have deleted a swap partition or removed pieces of LVM, remove all references to the partition from the kernel command line in the /etc/default/grub file, and regenerate GRUB configuration:

   • On a BIOS-based system:

     # grub2-mkconfig --output=/etc/grub2.cfg

   • On a UEFI-based system:

     # grub2-mkconfig --output=/etc/grub2-efi.cfg

10. To register the changes in the early boot system, rebuild the initramfs file system:

    # dracut --force --verbose

Procedure

1. Install the targetcli tool:

   # yum install targetcli

2. Start the target service:

   # systemctl start target

3. Configure target to start at boot time:

   # systemctl enable target

4. Open port 3260 in the firewall and reload the firewall configuration:

   # firewall-cmd --permanent --add-port=3260/tcp
   Success
   
   # firewall-cmd --reload
   Success

Procedure

1. Navigate to the iSCSI directory:

   /> iscsi/

   Note

   The cd command is used to change directories as well as to list the path to move into.

2. Use one of the following options to create an iSCSI target:

   1. Creating an iSCSI target using a default target name:

      /iscsi> create
      
      Created target
      iqn.2003-01.org.linux-iscsi.hostname.x8664:sn.78b473f296ff
      Created TPG1

   2. Creating an iSCSI target using a specific name:

      /iscsi> create iqn.2006-04.com.example:444
      
      Created target iqn.2006-04.com.example:444
      Created TPG1
      Here iqn.2006-04.com.example:444 is target_iqn_name

      Replace iqn.2006-04.com.example:444 with the specific target name.

3. Verify the newly created target:

   /iscsi> ls
   
   o- iscsi.......................................[1 Target]
       o- iqn.2006-04.com.example:444................[1 TPG]
           o- tpg1...........................[enabled, auth]
              o- acls...............................[0 ACL]
               o- luns...............................[0 LUN]
              o- portals.........................[0 Portal]

Procedure

1. Navigate to the fileio/ from the backstores/ directory:

   /> backstores/fileio

2. Create a fileio storage object:

   /backstores/fileio> create file1 /tmp/disk1.img 200M write_back=false
   
   Created fileio file1 with size 209715200

Procedure

1. Navigate to the block/ from the backstores/ directory:

   /> backstores/block/

2. Create a block backstore:

   /backstores/block> create name=block_backend dev=/dev/sdb
   
   Generating a wwn serial.
   Created block storage object block_backend using /dev/vdb.

Procedure

1. Navigate to the pscsi/ from the backstores/ directory:

   /> backstores/pscsi/

2. Create a pscsi backstore for a physical SCSI device, a TYPE_ROM device using /dev/sr0 in this example:

   /backstores/pscsi> create name=pscsi_backend dev=/dev/sr0
   
   Generating a wwn serial.
   Created pscsi storage object pscsi_backend using /dev/sr0

Procedure

1. Navigate to the ramdisk/ from the backstores/ directory:

   /> backstores/ramdisk/

2. Create a 1GB RAM disk backstore:

   /backstores/ramdisk> create name=rd_backend size=1GB
   
   Generating a wwn serial.
   Created rd_mcp ramdisk rd_backend with size 1GB.

Procedure

1. Navigate to the TPG directory:

   /iscsi> iqn.2006-04.example:444/tpg1/

2. Use one of the following options to create an iSCSI portal:

   1. Creating a default portal uses the default iSCSI port 3260 and allows the target to listen to all IP addresses on that port:

      /iscsi/iqn.20...mple:444/tpg1> portals/ create
      
      Using default IP port 3260
      Binding to INADDR_Any (0.0.0.0)
      Created network portal 0.0.0.0:3260

      Note

      When an iSCSI target is created, a default portal is also created. This portal is set to listen to all IP addresses with the default port number that is: 0.0.0.0:3260.

      To remove the default portal, use the following command:

      /iscsi/iqn-name/tpg1/portals delete ip_address=0.0.0.0 ip_port=3260

   2. Creating a portal using a specific IP address:

      /iscsi/iqn.20...mple:444/tpg1> portals/ create 192.168.122.137
      
      Using default IP port 3260
      Created network portal 192.168.122.137:3260

Procedure

1. Create LUNs of already created storage objects:

   /iscsi/iqn.20...mple:444/tpg1> luns/ create /backstores/ramdisk/rd_backend
   Created LUN 0.
   
   /iscsi/iqn.20...mple:444/tpg1> luns/ create /backstores/block/block_backend
   Created LUN 1.
   
   /iscsi/iqn.20...mple:444/tpg1> luns/ create /backstores/fileio/file1
   Created LUN 2.

2. Verify the created LUNs:

   /iscsi/iqn.20...mple:444/tpg1> ls
   
   o- tpg.................................. [enambled, auth]
       o- acls ......................................[0 ACL]
       o- luns .....................................[3 LUNs]
       |  o- lun0.........................[ramdisk/ramdisk1]
       |  o- lun1.................[block/block1 (/dev/vdb1)]
       |  o- lun2...................[fileio/file1 (/foo.img)]
       o- portals ................................[1 Portal]
           o- 192.168.122.137:3260......................[OK]

   Default LUN name starts at 0.

   Important

   By default, LUNs are created with read-write permissions. If a new LUN is added after ACLs are created, LUN automatically maps to all available ACLs and can cause a security risk. To create a LUN with read-only permissions, see Creating a read-only iSCSI LUN.

3. Configure ACLs. For more information, see Creating an iSCSI ACL.

Procedure

1. Set read-only permissions:

   /> set global auto_add_mapped_luns=false
   
   Parameter auto_add_mapped_luns is now 'false'.

   This prevents the auto mapping of LUNs to existing ACLs allowing the manual mapping of LUNs.

2. Navigate to the initiator_iqn_name directory:

   /> iscsi/target_iqn_name/tpg1/acls/initiator_iqn_name/

3. Create the LUN:

   /iscsi/target_iqn_name/tpg1/acls/initiator_iqn_name> create mapped_lun=next_sequential_LUN_number tpg_lun_or_backstore=backstore write_protect=1

   Example:

   /iscsi/target_iqn_name/tpg1/acls/2006-04.com.example.foo:888> create mapped_lun=1 tpg_lun_or_backstore=/backstores/block/block2 write_protect=1
   
   Created LUN 1.
   Created Mapped LUN 1.

4. Verify the created LUN:

   /iscsi/target_iqn_name/tpg1/acls/2006-04.com.example.foo:888> ls
    o- 2006-04.com.example.foo:888 .. [Mapped LUNs: 2]
    | o- mapped_lun0 .............. [lun0 block/disk1 (rw)]
    | o- mapped_lun1 .............. [lun1 block/disk2 (ro)]

   The mapped_lun1 line now has (ro) at the end (unlike mapped_lun0’s (rw)) stating that it is read-only.

5. Configure ACLs. For more information, see Creating an iSCSI ACL.

Procedure

1. Navigate to the acls directory

   /iscsi/iqn.20...mple:444/tpg1> acls/

2. Use one of the following options to create an ACL :

   1. Using the initiator name from /etc/iscsi/initiatorname.iscsi file on the initiator.

   2. Using a name that is easier to remember, see section Creating an iSCSI initiator to ensure ACL matches the initiator.

      /iscsi/iqn.20...444/tpg1/acls> create iqn.2006-04.com.example.foo:888
      
      Created Node ACL for iqn.2006-04.com.example.foo:888
      Created mapped LUN 2.
      Created mapped LUN 1.
      Created mapped LUN 0.

      Note

      The global setting auto_add_mapped_luns used in the preceding example, automatically maps LUNs to any created ACL.

      You can set user-created ACLs within the TPG node on the target server:

      /iscsi/iqn.20...scsi:444/tpg1> set attribute generate_node_acls=1

Procedure

1. Set attribute authentication:

   /iscsi/iqn.20...mple:444/tpg1> set attribute authentication=1
   
   Parameter authentication is now '1'.

2. Set userid and password:

   /tpg1> set auth userid=redhat
   Parameter userid is now 'redhat'.
   
   /iscsi/iqn.20...689dcbb3/tpg1> set auth password=redhat_passwd
   Parameter password is now 'redhat_passwd'.

Procedure

1. Log off from the target:

   # iscsiadm -m node -T iqn.2006-04.example:444 -u

   For more information on how to log in to the target, see Creating an iSCSI initiator.

2. Remove the entire target, including all ACLs, LUNs, and portals:

   /> iscsi/ delete iqn.2006-04.com.example:444

   Replace iqn.2006-04.com.example:444 with the target_iqn_name.

   • To remove an iSCSI backstore:

     /> backstores/backstore-type/ delete block_backend

     • Replace backstore-type with either fileio, block, pscsi, or ramdisk.
     • Replace block_backend with the backstore-name you want to delete.

   • To remove parts of an iSCSI target, such as an ACL:

     /> /iscsi/iqn-name/tpg/acls/ delete iqn.2006-04.com.example:444

Procedure

1. Install iscsi-initiator-utils on client machine:

   # yum install iscsi-initiator-utils

2. Check the initiator name:

   # cat /etc/iscsi/initiatorname.iscsi
   
   InitiatorName=2006-04.com.example.foo:888

3. If the ACL was given a custom name in Creating an iSCSI ACL, modify the /etc/iscsi/initiatorname.iscsi file accordingly.

   # vi /etc/iscsi/initiatorname.iscsi

4. Discover the target and log in to the target with the displayed target IQN:

   # iscsiadm -m discovery -t st -p 10.64.24.179
       10.64.24.179:3260,1 iqn.2006-04.example:444
   
   # iscsiadm -m node -T iqn.2006-04.example:444 -l
       Logging in to [iface: default, target: iqn.2006-04.example:444, portal: 10.64.24.179,3260] (multiple)
       Login to [iface: default, target: iqn.2006-04.example:444, portal: 10.64.24.179,3260] successful.

   Replace 10.64.24.179 with the target-ip-address.

   You can use this procedure for any number of initiators connected to the same target if their respective initiator names are added to the ACL as described in the Creating an iSCSI ACL.

5. Find the iSCSI disk name and create a file system on this iSCSI disk:

   # grep "Attached SCSI" /var/log/messages
   
   # mkfs.ext4 /dev/disk_name

   Replace disk_name with the iSCSI disk name displayed in the /var/log/messages file.

6. Mount the file system:

   # mkdir /mount/point
   
   # mount /dev/disk_name /mount/point

   Replace /mount/point with the mount point of the partition.

7. Edit the /etc/fstab file to mount the file system automatically when the system boots:

   # vi /etc/fstab
   
   /dev/disk_name /mount/point ext4 _netdev 0 0

   Replace disk_name with the iSCSI disk name and /mount/point with the mount point of the partition.

Procedure

1. Enable CHAP authentication in the iscsid.conf file:

   # vi /etc/iscsi/iscsid.conf
   
   node.session.auth.authmethod = CHAP

   By default, the node.session.auth.authmethod is set to None

2. Add target username and password in the iscsid.conf file:

   node.session.auth.username = redhat
   node.session.auth.password = redhat_passwd

3. Start the iscsid daemon:

   # systemctl start iscsid.service

Procedure

1. Install the iscsi-initiator-utils on client machine:

   # yum install iscsi-initiator-utils

2. Find information about the running sessions:

   # iscsiadm -m session -P 3

   This command displays the session or device state, session ID (sid), some negotiated parameters, and the SCSI devices accessible through the session.

   • For shorter output, for example, to display only the sid-to-node mapping, run:

     # iscsiadm -m session -P 0
             or
     # iscsiadm -m session
     
     tcp [2] 10.15.84.19:3260,2 iqn.1992-08.com.netapp:sn.33615311
     tcp [3] 10.15.85.19:3260,3 iqn.1992-08.com.netapp:sn.33615311

     These commands print the list of running sessions in the following format: driver [sid] target_ip:port,target_portal_group_tag proper_target_name.

Procedure

1. Determine which devices are paths for a multipath logical unit:

   multipath -ll

2. Re-scan Fibre Channel logical units on a system that uses multipathing:

   $ echo 1 > /sys/block/sdX/device/rescan

Procedure

1. Install the fcoe-utils package:

   # yum install fcoe-utils

2. Copy the /etc/fcoe/cfg-ethx template file to /etc/fcoe/cfg-interface_name. For example, if you want to configure the enp1s0 interface to use FCoE, enter the following command:

   # cp /etc/fcoe/cfg-ethx /etc/fcoe/cfg-enp1s0

3. Enable and start the fcoe service:

   # systemctl enable --now fcoe

4. Discover the FCoE VLAN on interface enp1s0, create a network device for the discovered VLAN, and start the initiator:

   # fipvlan -s -c enp1s0
   Created VLAN device enp1s0.200
   Starting FCoE on interface enp1s0.200
   Fibre Channel Forwarders Discovered
   interface       | VLAN | FCF MAC
   ------------------------------------------
   enp1s0          | 200  | 00:53:00:a7:e7:1b

5. Optional: Display details about the discovered targets, the LUNs, and the devices associated with the LUNs:

   # fcoeadm -t
   Interface:        enp1s0.200
   Roles:            FCP Target
   Node Name:        0x500a0980824acd15
   Port Name:        0x500a0982824acd15
   Target ID:        0
   MaxFrameSize:     2048 bytes
   OS Device Name:   rport-11:0-1
   FC-ID (Port ID):  0xba00a0
   State:            Online
   
   LUN ID  Device Name   Capacity   Block Size  Description
   ------  -----------  ----------  ----------  ---------------------
        0  sdb           28.38 GiB      512     NETAPP LUN (rev 820a)
        ...

   This example shows that LUN 0 from the SAN has been attached to the host as the /dev/sdb device.

Procedure

1. Disable swapping for the associated logical volume:

   # swapoff -v /dev/VolGroup00/LogVol01

2. Resize the LVM2 logical volume by 2 GB:

   # lvresize /dev/VolGroup00/LogVol01 -L +2G

3. Format the new swap space:

   # mkswap /dev/VolGroup00/LogVol01

4. Enable the extended logical volume:

   # swapon -v /dev/VolGroup00/LogVol01

Procedure

1. Create the LVM2 logical volume of size 2 GB:

   # lvcreate VolGroup00 -n LogVol02 -L 2G

2. Format the new swap space:

   # mkswap /dev/VolGroup00/LogVol02

3. Add the following entry to the /etc/fstab file:

   /dev/VolGroup00/LogVol02 swap swap defaults 0 0

4. Regenerate mount units so that your system registers the new configuration:

   # systemctl daemon-reload

5. Activate swap on the logical volume:

   # swapon -v /dev/VolGroup00/LogVol02

Procedure

1. Determine the size of the new swap file in megabytes and multiply by 1024 to determine the number of blocks. For example, the block size of a 64 MB swap file is 65536.

2. Create an empty file:

   # dd if=/dev/zero of=/swapfile bs=1024 count=65536

   Replace 65536 with the value equal to the desired block size.

3. Set up the swap file with the command:

   # mkswap /swapfile

4. Change the security of the swap file so it is not world readable.

   # chmod 0600 /swapfile

5. Edit the /etc/fstab file with the following entries to enable the swap file at boot time:

   /swapfile swap swap defaults 0 0

   The next time the system boots, it activates the new swap file.

6. Regenerate mount units so that your system registers the new /etc/fstab configuration:

   # systemctl daemon-reload

7. Activate the swap file immediately:

   # swapon /swapfile

Procedure

1. Disable swapping for the associated logical volume:

   # swapoff -v /dev/VolGroup00/LogVol01

2. Reduce the LVM2 logical volume by 512 MB:

   # lvreduce /dev/VolGroup00/LogVol01 -L -512M

3. Format the new swap space:

   # mkswap /dev/VolGroup00/LogVol01

4. Activate swap on the logical volume:

   # swapon -v /dev/VolGroup00/LogVol01

Procedure

1. Disable swapping for the associated logical volume:

   # swapoff -v /dev/VolGroup00/LogVol02

2. Remove the LVM2 logical volume:

   # lvremove /dev/VolGroup00/LogVol02

3. Remove the following associated entry from the /etc/fstab file:

   /dev/VolGroup00/LogVol02 swap swap defaults 0 0

4. Regenerate mount units so that your system registers the new configuration:

   # systemctl daemon-reload

Procedure

1. At a shell prompt, execute the following command to disable the swap file, where /swapfile is the swap file:

   # swapoff -v /swapfile

2. Remove its entry from the /etc/fstab file accordingly.

3. Regenerate mount units so that your system registers the new configuration:

   # systemctl daemon-reload

4. Remove the actual file:

   # rm /swapfile

1. Create a snapshot or copy of the root file system.
2. Use the boom command to create a boot entry for the current (older) environment.
3. Upgrade your Red Hat Enterprise Linux system.
4. Reboot the system, and select the version that you want to use.

Procedure

1. Create a snapshot of your root logical volume:

   • If your root file system uses thin provisioning, create a thin snapshot:

     While creating a thin snapshot, do not define the snapshot size. Snapshot is allocated from the thin pool.

     # lvcreate -s rhel/root -n root_snapshot_before_changes

     Here:

     • -s is used to create the snapshot
     • rhel/root is the file system being copied in the logical volume
     • -n root_snapshot_before_changes is the name of the snapshot

   • If your root file system uses thick provisioning, create a thick snapshot:

     While creating a thick snapshot, define the snapshot size that is able to hold all the changes during the upgrade.

     # lvcreate -s  rhel/root -n root_snapshot_before_changes -L 25g

     Here:

     • -s is used to create the snapshot
     • rhel/root is the file system being copied
     • -n root_snapshot_before_changes is the name of the snapshot

     • -L 25g is the snapshot size. This snapshot must be able to hold all the changes during the upgrade

       Important

       After creating the snapshot, any additional system changes are not included.

2. Create the profile:

   # boom profile create --from-host --uname-pattern el7

   Note

   If you want to create the boom profile on Red Hat Enterprise Linux 8, use the el8 as the uname-pattern.

3. Create a snapshot boot entry of the original system, using backup copies of the original boot images:

   1. For the boom-1.2 or later version:

      # boom create --backup --title "Root LV snapshot before changes" --rootlv rhel/root_snapshot_before_changes

      Here:

      • --title Root LV snapshot before changes is the name of the boot entry, which displays in the list during system startup
      • --rootlv is the root logical volume that corresponds to the new boot entry

   2. For the boom-1.1 or earlier version:

      # cp /boot/vmlinuz-$(uname r) /boot/vmlinuz$(uname -r).bak
      
      # cp /boot/initramfs-$(uname r).img /boot/initramfs$(uname -r).img.bak
      
      # boom create -title "Root LV snapshot before changes" --rootlv rhel/root_snapshot_before_changes --linux /boot/vmlinuz$(uname r).bak --initrd /boot/initramfs$(uname -r).img.bak

      If you execute the boom create command for the first time, the following message displays:

      WARNING - Boom configuration not found in grub.cfg
      
      WARNING - Run 'grub2-mkconfig > /boot/grub2/grub.cfg' to enable

      To enable Boom in GRUB 2:

      # grub2-mkconfig > /boot/grub2/grub.cfg

4. Upgrade to Red Hat Enterprise Linux 8 using the Leapp utility:

   # leapp preupgrade

   Review and address if any blockers indicated in the leapp preupgrade command report.

5. After resolving the blockers identified in the pre-upgrade reports, re-run the upgrade command with the --reboot option:

   # leapp upgrade --reboot

   This command reboots into the upgraded boot entry created by the leapp utility and proceeds to execute the in-place upgrade to Red Hat Enterprise Linux 8. The reboot argument initiates an automatic system restart after the upgrade process.

   During reboot, the GRUB 2 screen is displayed:

   
   Note

   If you are on the Red Hat Enterprise Linux 8 system, the Snapshots sub-menu from the GRUB2 boot screen is not available.

Procedure

1. Reboot the system:

   # reboot

2. Select the desired boot entry from the GRUB 2 boot loader screen.

   

Procedure

1. Boot into Red Hat Enterprise Linux 8 from the GRUB 2 entry. The following output confirms that the new snapshot is selected:

   # boom list
   BootID  Version                    Name                            RootDevice
   6d2ec72 3.10.0-957.21.3.el7.x86_64 Red Hat Enterprise Linux Server /dev/rhel/root_snapshot_before_changes

2. Delete the snapshot entry using the BootID value:

   # boom delete --boot-id 6d2ec72

   This deletes the entry from the GRUB 2 menu.

3. Remove the LV snapshot:

   # lvremove rhel/root_snapshot_before_changes
   Do you really want to remove active logical volume rhel/root_snapshot_before_changes? [y/n]: y
         Logical volume "root_snapshot_before_changes" successfully removed

   Additional resources

   • The boom man page.

Procedure

1. Merge the snapshot:

   # lvconvert --merge rhel/root_snapshot_before_changes

2. Create a rollback boot entry for the merged snapshot:

   1. For the boom-1.2 or later version:

      boom create --backup --title "RHEL Rollback" --rootlv rhel/root

   2. For the boom-1.1 or earlier version:

      boom create --title "RHEL Rollback" --rootlv rhel/root --linux /boot/vmlinuz$(uname r).bak --initrd /boot/initramfs$(uname -r).img.bak

3. Optional: Boot rollback environment and restore the system state:

   # reboot

   Once the system is rebooted, select the RHEL Rollback boot entry using the arrow keys and press Enter to boot this entry.

   The system automatically starts the snapshot merge operation once the root logical volume is activated.

   Note

   Once the merge operation is started, the snapshot volume is no longer available. After successfully booting the RHEL Rollback boot entry, the Root LV snapshot before changes boot entry no longer works because it is now merged into the original logical volume. Merging a snapshot logical volume, destroys the snapshot and restores the prior state of the origin volume.

4. Optional: Once the merge operation is completed, remove the unused entries and restore the original boot entry:

   1. Remove the unused Red Hat Enterprise Linux 8 boot entries from the /boot file system and refresh the Grub2 configuration:

      # rm -f /boot/el8
      # grub2-mkconfig -o /boot/grub2/grub.cfg

   2. Restore the original Red Hat Enterprise Linux 7 boot entry:

      # new-kernel-pkg --update $(uname -r)

5. After successful rollback to the system, delete the boom boot entry:

   # boom list
   # boom delete boot-id

Procedure

1. Create the nvmet-rdma subsystem:

   # modprobe nvmet-rdma
   
   # mkdir /sys/kernel/config/nvmet/subsystems/testnqn
   
   # cd /sys/kernel/config/nvmet/subsystems/testnqn

   Replace testnqn with the subsystem name.

2. Allow any host to connect to this target:

   # echo 1 > attr_allow_any_host

3. Configure a namespace:

   # mkdir namespaces/10
   
   # cd namespaces/10

   Replace 10 with the namespace number

4. Set a path to the NVMe device:

   # echo -n /dev/nvme0n1 > device_path

5. Enable the namespace:

   # echo 1 > enable

6. Create a directory with an NVMe port:

   # mkdir /sys/kernel/config/nvmet/ports/1
   
   # cd /sys/kernel/config/nvmet/ports/1

7. Display the IP address of mlx5_ib0:

   # ip addr show mlx5_ib0
   
   8: mlx5_ib0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 4092 qdisc mq state UP group default qlen 256
       link/infiniband 00:00:06:2f:fe:80:00:00:00:00:00:00:e4:1d:2d:03:00:e7:0f:f6 brd 00:ff:ff:ff:ff:12:40:1b:ff:ff:00:00:00:00:00:00:ff:ff:ff:ff
       inet 172.31.0.202/24 brd 172.31.0.255 scope global noprefixroute mlx5_ib0
          valid_lft forever preferred_lft forever
       inet6 fe80::e61d:2d03:e7:ff6/64 scope link noprefixroute
          valid_lft forever preferred_lft forever

8. Set the transport address for the target:

   # echo -n 172.31.0.202 > addr_traddr

9. Set RDMA as the transport type:

   # echo rdma > addr_trtype
   
   # echo 4420 > addr_trsvcid

10. Set the address family for the port:

    # echo ipv4 > addr_adrfam

11. Create a soft link:

    # ln -s /sys/kernel/config/nvmet/subsystems/testnqn   /sys/kernel/config/nvmet/ports/1/subsystems/testnqn

Procedure

1. Install the nvmetcli package:

   # yum install nvmetcli

2. Download the rdma.json file:

   # wget http://git.infradead.org/users/hch/nvmetcli.git/blob_plain/0a6b088db2dc2e5de11e6f23f1e890e4b54fee64:/rdma.json

3. Edit the rdma.json file and change the traddr value to 172.31.0.202.

4. Setup the target by loading the NVMe target configuration file:

   # nvmetcli restore rdma.json

Procedure

1. Install the nvme-cli tool:

   # yum install nvme-cli

2. Load the nvme-rdma module if it is not loaded:

   # modprobe nvme-rdma

3. Discover available subsystems on the NVMe target:

   # nvme discover -t rdma -a 172.31.0.202 -s 4420
   
   Discovery Log Number of Records 1, Generation counter 2
   =====Discovery Log Entry 0======
   trtype:  rdma
   adrfam:  ipv4
   subtype: nvme subsystem
   treq:    not specified, sq flow control disable supported
   portid:  1
   trsvcid: 4420
   subnqn:  testnqn
   traddr:  172.31.0.202
   rdma_prtype: not specified
   rdma_qptype: connected
   rdma_cms:    rdma-cm
   rdma_pkey: 0x0000

4. Connect to the discovered subsystems:

   # nvme connect -t rdma -n testnqn -a 172.31.0.202 -s 4420
   
   # lsblk
   NAME                         MAJ:MIN RM   SIZE RO TYPE MOUNTPOINT
   sda                            8:0    0 465.8G  0 disk
   ├─sda1                         8:1    0     1G  0 part /boot
   └─sda2                         8:2    0 464.8G  0 part
     ├─rhel_rdma--virt--03-root 253:0    0    50G  0 lvm  /
     ├─rhel_rdma--virt--03-swap 253:1    0     4G  0 lvm  [SWAP]
     └─rhel_rdma--virt--03-home 253:2    0 410.8G  0 lvm  /home
   nvme0n1
   
   # cat /sys/class/nvme/nvme0/transport
   rdma

   Replace testnqn with the NVMe subsystem name.

   Replace 172.31.0.202 with the target IP address.

   Replace 4420 with the port number.

Procedure

1. Install the nvme-cli tool:

   # yum install nvme-cli

   This creates the hostnqn file in the /etc/nvme/ directory. The hostnqn file identifies the NVMe host.

   To generate a new hostnqn, use the following command:

   # nvme gen-hostnqn

2. Find the WWNN and WWPN identifiers of the local and remote ports and use the output to find the subsystem NQN:

   # cat /sys/class/scsi_host/host*/nvme_info
   
   NVME Initiator Enabled
   XRI Dist lpfc0 Total 6144 IO 5894 ELS 250
   NVME LPORT lpfc0 WWPN x10000090fae0b5f5 WWNN x20000090fae0b5f5 DID x010f00 ONLINE
   NVME RPORT       WWPN x204700a098cbcac6 WWNN x204600a098cbcac6 DID x01050e TARGET DISCSRVC ONLINE
   
   NVME Statistics
   LS: Xmt 000000000e Cmpl 000000000e Abort 00000000
   LS XMIT: Err 00000000  CMPL: xb 00000000 Err 00000000
   Total FCP Cmpl 00000000000008ea Issue 00000000000008ec OutIO 0000000000000002
       abort 00000000 noxri 00000000 nondlp 00000000 qdepth 00000000 wqerr 00000000 err 00000000
   FCP CMPL: xb 00000000 Err 00000000

   # nvme discover --transport fc \
                   --traddr nn-0x204600a098cbcac6:pn-0x204700a098cbcac6 \
                   --host-traddr nn-0x20000090fae0b5f5:pn-0x10000090fae0b5f5
   
   Discovery Log Number of Records 2, Generation counter 49530
   =====Discovery Log Entry 0======
   trtype:  fc
   adrfam:  fibre-channel
   subtype: nvme subsystem
   treq:    not specified
   portid:  0
   trsvcid: none
   subnqn:  nqn.1992-08.com.netapp:sn.e18bfca87d5e11e98c0800a098cbcac6:subsystem.st14_nvme_ss_1_1
   traddr:  nn-0x204600a098cbcac6:pn-0x204700a098cbcac6

   Replace nn-0x204600a098cbcac6:pn-0x204700a098cbcac6 with the traddr.

   Replace nn-0x20000090fae0b5f5:pn-0x10000090fae0b5f5 with the host-traddr.

3. Connect to the NVMe target using the nvme-cli:

   # nvme connect --transport fc \
                  --traddr nn-0x204600a098cbcac6:pn-0x204700a098cbcac6 \
                  --host-traddr nn-0x20000090fae0b5f5:pn-0x10000090fae0b5f5 \
                  -n nqn.1992-08.com.netapp:sn.e18bfca87d5e11e98c0800a098cbcac6:subsystem.st14_nvme_ss_1_1

   Replace nn-0x204600a098cbcac6:pn-0x204700a098cbcac6 with the traddr.

   Replace nn-0x20000090fae0b5f5:pn-0x10000090fae0b5f5 with the host-traddr.

   Replace nqn.1992-08.com.netapp:sn.e18bfca87d5e11e98c0800a098cbcac6:subsystem.st14_nvme_ss_1_1 with the subnqn.

Procedure

1. Install the nvme-cli tool:

   # yum install nvme-cli

   This creates the hostnqn file in the /etc/nvme/ directory. The hostnqn file identifies the NVMe host.

   To generate a new hostnqn, use the following command:

   # nvme gen-hostnqn

2. Reload the qla2xxx module:

   # rmmod qla2xxx
   # modprobe qla2xxx

3. Find the WWNN and WWPN identifiers of the local and remote ports:

   # dmesg |grep traddr
   
   [    6.139862] qla2xxx [0000:04:00.0]-ffff:0: register_localport: host-traddr=nn-0x20000024ff19bb62:pn-0x21000024ff19bb62 on portID:10700
   [    6.241762] qla2xxx [0000:04:00.0]-2102:0: qla_nvme_register_remote: traddr=nn-0x203b00a098cbcac6:pn-0x203d00a098cbcac6 PortID:01050d

   Using these host-traddr and traddr values, find the subsystem NQN:

   # nvme discover --transport fc \
                   --traddr nn-0x203b00a098cbcac6:pn-0x203d00a098cbcac6 \
                   --host-traddr nn-0x20000024ff19bb62:pn-0x21000024ff19bb62
   
   Discovery Log Number of Records 2, Generation counter 49530
   =====Discovery Log Entry 0======
   trtype:  fc
   adrfam:  fibre-channel
   subtype: nvme subsystem
   treq:    not specified
   portid:  0
   trsvcid: none
   subnqn:  nqn.1992-08.com.netapp:sn.c9ecc9187b1111e98c0800a098cbcac6:subsystem.vs_nvme_multipath_1_subsystem_468
   traddr:  nn-0x203b00a098cbcac6:pn-0x203d00a098cbcac6

   Replace nn-0x203b00a098cbcac6:pn-0x203d00a098cbcac6 with the traddr.

   Replace nn-0x20000024ff19bb62:pn-0x21000024ff19bb62 with the host-traddr.

4. Connect to the NVMe target using the nvme-cli tool:

   # nvme connect  --transport fc \
                   --traddr nn-0x203b00a098cbcac6:pn-0x203d00a098cbcac6 \
                   --host-traddr nn-0x20000024ff19bb62:pn-0x21000024ff19bb62 \
                   -n nqn.1992-08.com.netapp:sn.c9ecc9187b1111e98c0800a098cbcac6:subsystem.vs_nvme_multipath_1_subsystem_468

   Replace nn-0x203b00a098cbcac6:pn-0x203d00a098cbcac6 with the traddr.

   Replace nn-0x20000024ff19bb62:pn-0x21000024ff19bb62 with the host-traddr.

   Replace nqn.1992-08.com.netapp:sn.c9ecc9187b1111e98c0800a098cbcac6:subsystem.vs_nvme_multipath_1_subsystem_468 with the subnqn.

Procedure

1. Install the nvme-cli tool:

   # yum install nvme-cli

   This tool creates the hostnqn file in the /etc/nvme/ directory, which identifies the NVMe host.

2. Find the nvme hostid and hostnqn:

   # cat /etc/nvme/hostnqn
   nqn.2014-08.org.nvmexpress:uuid:8ae2b12c-3d28-4458-83e3-658e571ed4b8
   
   # cat /etc/nvme/hostid
   09e2ce17-ccc9-412d-8dcf-2b0a1d581ee3

   Use the hostid and hostnqn values to configure the NVMe/TCP target subsystem.

3. Check the status of the controller:

   # nmcli device show ens6
   GENERAL.DEVICE:                         ens6
   GENERAL.TYPE:                           ethernet
   GENERAL.HWADDR:                         52:57:02:12:02:02
   GENERAL.MTU:                            1500
   GENERAL.STATE:                          30 (disconnected)
   GENERAL.CONNECTION:                     --
   GENERAL.CON-PATH:                       --
   WIRED-PROPERTIES.CARRIER:               on

4. Configure the host network for a newly installed Ethernet controller with a static IP address:

   # nmcli connection add con-name ens6 ifname ens6 type ethernet ip4 192.168.101.154/24 gw4 192.168.101.1

   Here, replace 192.168.101.154 with the host IP address.

   # nmcli connection mod ens6 ipv4.method manual
   # nmcli connection up ens6

   Since a new network is created to connect the NVMe/TCP host to the NVMe/TCP target, execute this step on the target too.

Procedure

1. Load the nvme_tcp module if not already:

   # modprobe nvme_tcp

2. Discover the available subsystems on the NVMe target:

   # nvme discover --transport=tcp --traddr=192.168.101.55 --host-traddr=192.168.101.154 --trsvcid=4420
   
   Discovery Log Number of Records 2, Generation counter 7
   =====Discovery Log Entry 0======
   trtype:  tcp
   adrfam:  ipv4
   subtype: current discovery subsystem
   treq:	not specified, sq flow control disable supported
   portid:  2
   trsvcid: 4420
   subnqn:  nqn.2014-08.org.nvmexpress.discovery
   traddr:  192.168.101.55
   eflags:  not specified
   sectype: none
   =====Discovery Log Entry 1======
   trtype:  tcp
   adrfam:  ipv4
   subtype: nvme subsystem
   treq:	not specified, sq flow control disable supported
   portid:  2
   trsvcid: 4420
   subnqn:  nqn.2014-08.org.nvmexpress:uuid:0c468c4d-a385-47e0-8299-6e95051277db
   traddr:  192.168.101.55
   eflags:  not specified
   sectype: none

   Here, 192.168.101.55 is the NVMe/TCP target IP address and 192.168.101.154 is the NVMe/TCP host IP address.

3. Configure the /etc/nvme/discovery.conf file to add the parameters used in the nvme discover command :

   # echo "--transport=tcp --traddr=192.168.101.55 --host-traddr=192.168.101.154 --trsvcid=4420" >> /etc/nvme/discovery.conf

4. Connect the NVMe/TCP host to the target system:

   # nvme connect-all

Procedure

1. Check if native NVMe multipathing is enabled in the kernel:

   # cat /sys/module/nvme_core/parameters/multipath

   The command displays one of the following:

   N

   Native NVMe multipathing is disabled.

   Y

   Native NVMe multipathing is enabled.

2. If native NVMe multipathing is disabled, enable it using one of the following methods:

   • Using a kernel option:

     1. Add the nvme_core.multipath=Y option on the kernel command line:

        # grubby --update-kernel=ALL --args="nvme_core.multipath=Y"

     2. On the 64-bit IBM Z architecture, update the boot menu:

        # zipl

     3. Reboot the system.

   • Using a kernel module configuration file:

     1. Create the /etc/modprobe.d/nvme_core.conf configuration file with the following content:

        options nvme_core multipath=Y

     2. Back up the initramfs file system:

        # cp /boot/initramfs-$(uname -r).img \
             /boot/initramfs-$(uname -r).bak.$(date +%m-%d-%H%M%S).img

     3. Rebuild the initramfs file system:

        # dracut --force --verbose

     4. Reboot the system.

3. Optional: On the running system, change the I/O policy on NVMe devices to distribute the I/O on all available paths:

   # echo "round-robin" > /sys/class/nvme-subsystem/nvme-subsys0/iopolicy

4. Optional: Set the I/O policy persistently using udev rules. Create the /etc/udev/rules.d/71-nvme-io-policy.rules file with the following content:

   ACTION=="add|change", SUBSYSTEM=="nvme-subsystem", ATTR{iopolicy}="round-robin"

Verification

1. Check that your system recognizes the NVMe devices:

   # nvme list
   
   Node             SN                   Model                                    Namespace Usage                      Format           FW Rev
   ---------------- -------------------- ---------------------------------------- --------- -------------------------- ---------------- --------
   /dev/nvme0n1     a34c4f3a0d6f5cec     Linux                                    1         250.06  GB / 250.06  GB    512   B +  0 B   4.18.0-2
   /dev/nvme0n2     a34c4f3a0d6f5cec     Linux                                    2         250.06  GB / 250.06  GB    512   B +  0 B   4.18.0-2

2. List all connected NVMe subsystems:

   # nvme list-subsys
   
   nvme-subsys0 - NQN=testnqn
   \
    +- nvme0 fc traddr=nn-0x20000090fadd597a:pn-0x10000090fadd597a host_traddr=nn-0x20000090fac7e1dd:pn-0x10000090fac7e1dd live
    +- nvme1 fc traddr=nn-0x20000090fadd5979:pn-0x10000090fadd5979 host_traddr=nn-0x20000090fac7e1dd:pn-0x10000090fac7e1dd live
    +- nvme2 fc traddr=nn-0x20000090fadd5979:pn-0x10000090fadd5979 host_traddr=nn-0x20000090fac7e1de:pn-0x10000090fac7e1de live
    +- nvme3 fc traddr=nn-0x20000090fadd597a:pn-0x10000090fadd597a host_traddr=nn-0x20000090fac7e1de:pn-0x10000090fac7e1de live

   Check the active transport type. For example, nvme0 fc indicates that the device is connected over the Fibre Channel transport, and nvme tcp indicates that the device is connected over TCP.

3. If you edited the kernel options, check that native NVMe multipathing is enabled on the kernel command line:

   # cat /proc/cmdline
   
   BOOT_IMAGE=[...] nvme_core.multipath=Y

4. Check that DM Multipath reports the NVMe namespaces as, for example, nvme0c0n1 through nvme0c3n1, and not as, for example, nvme0n1 through nvme3n1:

   # multipath -e -ll | grep -i nvme
   
   uuid.8ef20f70-f7d3-4f67-8d84-1bb16b2bfe03 [nvme]:nvme0n1 NVMe,Linux,4.18.0-2
   | `- 0:0:1    nvme0c0n1 0:0     n/a   optimized live
   | `- 0:1:1    nvme0c1n1 0:0     n/a   optimized live
   | `- 0:2:1    nvme0c2n1 0:0     n/a   optimized live
     `- 0:3:1    nvme0c3n1 0:0     n/a   optimized live
   
   uuid.44c782b4-4e72-4d9e-bc39-c7be0a409f22 [nvme]:nvme0n2 NVMe,Linux,4.18.0-2
   | `- 0:0:1    nvme0c0n1 0:0     n/a   optimized live
   | `- 0:1:1    nvme0c1n1 0:0     n/a   optimized live
   | `- 0:2:1    nvme0c2n1 0:0     n/a   optimized live
     `- 0:3:1    nvme0c3n1 0:0     n/a   optimized live

5. If you changed the I/O policy, check that round-robin is the active I/O policy on NVMe devices:

   # cat /sys/class/nvme-subsystem/nvme-subsys0/iopolicy
   
   round-robin

Procedure

1. Check that native NVMe multipathing is disabled:

   # cat /sys/module/nvme_core/parameters/multipath

   The command displays one of the following:

   N

   Native NVMe multipathing is disabled.

   Y

   Native NVMe multipathing is enabled.

2. If native NVMe multipathing is enabled, disable it:

   1. Remove the nvme_core.multipath=Y option from the kernel command line:

      # grubby --update-kernel=ALL --remove-args="nvme_core.multipath=Y"

   2. On the 64-bit IBM Z architecture, update the boot menu:

      # zipl

   3. Remove the options nvme_core multipath=Y line from the /etc/modprobe.d/nvme_core.conf file, if it is present.
   4. Reboot the system.

3. Make sure that DM Multipath is enabled:

   # systemctl enable --now multipathd.service

4. Distribute I/O on all available paths. Add the following content in the /etc/multipath.conf file:

   device {
     vendor "NVME"
     product ".*"
     path_grouping_policy    group_by_prio
   }

   Note

   The /sys/class/nvme-subsystem/nvme-subsys0/iopolicy configuration file has no effect on the I/O distribution when DM Multipath manages the NVMe devices.

5. Reload the multipathd service to apply the configuration changes:

   # multipath -r

6. Back up the initramfs file system:

   # cp /boot/initramfs-$(uname -r).img \
        /boot/initramfs-$(uname -r).bak.$(date +%m-%d-%H%M%S).img

7. Rebuild the initramfs file system:

   # dracut --force --verbose

Verification

1. Check that your system recognizes the NVMe devices:

   # nvme list
   
   Node             SN                   Model                                    Namespace Usage                      Format           FW Rev
   ---------------- -------------------- ---------------------------------------- --------- -------------------------- ---------------- --------
   /dev/nvme0n1     a34c4f3a0d6f5cec     Linux                                    1         250.06  GB / 250.06  GB    512   B +  0 B   4.18.0-2
   /dev/nvme0n2     a34c4f3a0d6f5cec     Linux                                    2         250.06  GB / 250.06  GB    512   B +  0 B   4.18.0-2
   /dev/nvme1n1     a34c4f3a0d6f5cec     Linux                                    1         250.06  GB / 250.06  GB    512   B +  0 B   4.18.0-2
   /dev/nvme1n2     a34c4f3a0d6f5cec     Linux                                    2         250.06  GB / 250.06  GB    512   B +  0 B   4.18.0-2
   /dev/nvme2n1     a34c4f3a0d6f5cec     Linux                                    1         250.06  GB / 250.06  GB    512   B +  0 B   4.18.0-2
   /dev/nvme2n2     a34c4f3a0d6f5cec     Linux                                    2         250.06  GB / 250.06  GB    512   B +  0 B   4.18.0-2
   /dev/nvme3n1     a34c4f3a0d6f5cec     Linux                                    1         250.06  GB / 250.06  GB    512   B +  0 B   4.18.0-2
   /dev/nvme3n2     a34c4f3a0d6f5cec     Linux                                    2         250.06  GB / 250.06  GB    512   B +  0 B   4.18.0-2

2. List all connected NVMe subsystems. Check that the command reports them as, for example, nvme0n1 through nvme3n2, and not as, for example, nvme0c0n1 through nvme0c3n1:

   # nvme list-subsys
   
   nvme-subsys0 - NQN=testnqn
   \
    +- nvme0 fc traddr=nn-0x20000090fadd5979:pn-0x10000090fadd5979 host_traddr=nn-0x20000090fac7e1dd:pn-0x10000090fac7e1dd live
    +- nvme1 fc traddr=nn-0x20000090fadd597a:pn-0x10000090fadd597a host_traddr=nn-0x20000090fac7e1dd:pn-0x10000090fac7e1dd live
    +- nvme2 fc traddr=nn-0x20000090fadd5979:pn-0x10000090fadd5979 host_traddr=nn-0x20000090fac7e1de:pn-0x10000090fac7e1de live
    +- nvme3 fc traddr=nn-0x20000090fadd597a:pn-0x10000090fadd597a host_traddr=nn-0x20000090fac7e1de:pn-0x10000090fac7e1de live

   # multipath -ll
   
   mpathae (uuid.8ef20f70-f7d3-4f67-8d84-1bb16b2bfe03) dm-36 NVME,Linux
   size=233G features='1 queue_if_no_path' hwhandler='0' wp=rw
   `-+- policy='service-time 0' prio=50 status=active
     |- 0:1:1:1  nvme0n1 259:0   active ready running
     |- 1:2:1:1  nvme1n1 259:2   active ready running
     |- 2:3:1:1  nvme2n1 259:4   active ready running
     `- 3:4:1:1  nvme3n1 259:6   active ready running
   
   mpathaf (uuid.44c782b4-4e72-4d9e-bc39-c7be0a409f22) dm-39 NVME,Linux
   size=233G features='1 queue_if_no_path' hwhandler='0' wp=rw
   `-+- policy='service-time 0' prio=50 status=active
     |- 0:1:2:2  nvme0n2 259:1   active ready running
     |- 1:2:2:2  nvme1n2 259:3   active ready running
     |- 2:3:2:2  nvme2n2 259:5   active ready running
     `- 3:4:2:2  nvme3n2 259:7   active ready running

Procedure

1. Optional: Select an existing TuneD profile on which your profile will be based. For a list of available profiles, see TuneD profiles distributed with RHEL.

   To see which profile is currently active, use:

   $ tuned-adm active

2. Create a new directory to hold your TuneD profile:

   # mkdir /etc/tuned/my-profile

3. Find the system unique identifier of the selected block device:

   $ udevadm info --query=property --name=/dev/device | grep -E '(WWN|SERIAL)'
   
   ID_WWN=0x5002538d00000000_
   ID_SERIAL=Generic-_SD_MMC_20120501030900000-0:0
   ID_SERIAL_SHORT=20120501030900000

   Note

   The command in the this example will return all values identified as a World Wide Name (WWN) or serial number associated with the specified block device. Although it is preferred to use a WWN, the WWN is not always available for a given device and any values returned by the example command are acceptable to use as the device system unique ID.

4. Create the /etc/tuned/my-profile/tuned.conf configuration file. In the file, set the following options:

   1. Optional: Include an existing profile:

      [main]
      include=existing-profile

   2. Set the selected disk scheduler for the device that matches the WWN identifier:

      [disk]
      devices_udev_regex=IDNAME=device system unique id
      elevator=selected-scheduler

      Here:

      • Replace IDNAME with the name of the identifier being used (for example, ID_WWN).

      • Replace device system unique id with the value of the chosen identifier (for example, 0x5002538d00000000).

        To match multiple devices in the devices_udev_regex option, enclose the identifiers in parentheses and separate them with vertical bars:

        devices_udev_regex=(ID_WWN=0x5002538d00000000)|(ID_WWN=0x1234567800000000)

5. Enable your profile:

   # tuned-adm profile my-profile

Verification steps

1. Verify that the TuneD profile is active and applied:

   $ tuned-adm active
   
   Current active profile: my-profile

   $ tuned-adm verify
   
   Verification succeeded, current system settings match the preset profile.
   See TuneD log file ('/var/log/tuned/tuned.log') for details.

2. Read the contents of the /sys/block/device/queue/scheduler file:

   # cat /sys/block/device/queue/scheduler
   
   [mq-deadline] kyber bfq none

   In the file name, replace device with the block device name, for example sdc.

   The active scheduler is listed in square brackets ([]).

Procedure

1. Find the system unique identifier of the block device:

   $ udevadm info --name=/dev/device | grep -E '(WWN|SERIAL)'
   E: ID_WWN=0x5002538d00000000
   E: ID_SERIAL=Generic-_SD_MMC_20120501030900000-0:0
   E: ID_SERIAL_SHORT=20120501030900000

   Note

   The command in the this example will return all values identified as a World Wide Name (WWN) or serial number associated with the specified block device. Although it is preferred to use a WWN, the WWN is not always available for a given device and any values returned by the example command are acceptable to use as the device system unique ID.

2. Configure the udev rule. Create the /etc/udev/rules.d/99-scheduler.rules file with the following content:

   ACTION=="add|change", SUBSYSTEM=="block", ENV{IDNAME}=="device system unique id", ATTR{queue/scheduler}="selected-scheduler"

   Here:

   • Replace IDNAME with the name of the identifier being used (for example, ID_WWN).
   • Replace device system unique id with the value of the chosen identifier (for example, 0x5002538d00000000).

3. Reload udev rules:

   # udevadm control --reload-rules

4. Apply the scheduler configuration:

   # udevadm trigger --type=devices --action=change

Procedure

1. Install the dracut-network package:

   # yum install dracut-network

2. After installing the dracut-network package, add the following line to /etc/dracut.conf:

   add_dracutmodules+="nfs"

To Configure tftp

1. Enable PXE booting over the network:

   # systemctl enable --now tftp

2. The tftp root directory (chroot) is located in /var/lib/tftpboot. Copy /usr/share/syslinux/pxelinux.0 to /var/lib/tftpboot/:

   # cp /usr/share/syslinux/pxelinux.0 /var/lib/tftpboot/

3. Copy /usr/share/syslinux/ldlinux.c32 to /var/lib/tftpboot/:

   # cp /usr/share/syslinux/ldlinux.c32 /var/lib/tftpboot/

4. Create a pxelinux.cfg directory inside the tftp root directory:

   # mkdir -p /var/lib/tftpboot/pxelinux.cfg/

5. After configuring tftp for diskless clients, configure DHCP, NFS, and the exported file system accordingly.

Procedure

1. Set up a DHCP server and enable PXE booting by adding the following configuration to /etc/dhcp/dhcpd.conf:

   allow booting;
   allow bootp;
   subnet 192.168.205.0 netmask 255.255.255.0 {
     pool
     {
       range 192.168.205.10 192.168.205.25;
     }
   
     option subnet-mask 255.255.255.0;
     option routers 192.168.205.1;
   }
   class "pxeclients" {
      match if substring(option vendor-class-identifier, 0, 9) = "PXEClient";
      next-server server-ip;
      filename "pxelinux.0";
   }

   This configuration will not boot over UEFI. To perform installation for UEFI, follow the procedure from this documentation: Configuring a TFTP server for UEFI-based clients. Also, note that the /etc/dhcp/dhcpd.conf is an example file.

   Note

   When libvirt virtual machines are used as a diskless client, libvirt provides the DHCP service and the stand alone DHCP server is not used. In this situation, network booting must be enabled with the bootp file='filename' option in the libvirt network configuration, virsh net-edit.

2. Enable dhcpd.service by entering the following command:

   # systemctl enable --now dhcpd.service

Procedure

1. Configure the NFS server to export the root directory by adding it to /etc/exports. For the instructions see NFS server configuration.

2. To accommodate completely diskless clients, the root directory should contain a complete Red Hat Enterprise Linux installation. You can either install a new base system or clone an existing installation:

   • To install Red Hat Enterprise Linux to the exported location, use the yum utility with the --installroot option:

     # yum install @Base kernel dracut-network nfs-utils \
           --installroot=exported-root-directory --releasever=/

   • To synchronize with a running system, use the rsync utility:

     # rsync -a -e ssh --exclude='/proc/' --exclude='/sys/' \
            example.com:/  exported-root-directory

     • Replace example.com with the hostname of the running system with which to synchronize via the rsync utility.

     • Replace exported-root-directory with the path to the exported file system.

       Note, that for this option you must have a separate existing running system, which you will clone to the server by the command above.

Configure File System

1. Select the kernel that diskless clients should use (vmlinuz-kernel-version) and copy it to the tftp boot directory:

   # cp /exported-root-directory/boot/vmlinuz-kernel-version /var/lib/tftpboot/

2. Create the initrd that is, initramfs-kernel-version.img file locally and move it to the exported root directory with NFS support:

   # dracut --add nfs initramfs-kernel-version.img kernel-version

   For example:

   # dracut --add nfs /exports/root/boot/initramfs-4.18.0-348.20.1.el8_5.x86_64.img 4.18.0-348.20.1.el8_5.x86_64

3. Change file permissions for initrd to 644 using the following command:

   # chmod 644 /exported-root-directory/boot/initramfs-<kernel-version>.img

   Warning

   If you do not change the initrd’s file permissions, the pxelinux.0 boot loader will fail with a "file not found" error.

4. Copy the resulting initramfs-kernel-version.img into the tftp boot directory:

   # cp /exported-root-directory/boot/initramfs-kernel-version.img /var/lib/tftpboot/

5. Edit the default boot configuration to use the initrd and kernel in the /var/lib/tftpboot/ directory. This configuration should instruct the diskless client’s root to mount the exported file system (/exported-root-directory) as read-write. Add the following configuration in the /var/lib/tftpboot/pxelinux.cfg/default file:

   default rhel8
   
   label rhel8
     kernel vmlinuz-kernel-version
     append initrd=initramfs-kernel-version.img root=nfs:server-ip:/exported-root-directory rw

   Replace server-ip with the IP address of the host machine on which the tftp and DHCP services reside.

6. Optionally, you can mount the system in read-only format by using the following configuration in the /var/lib/tftpboot/pxelinux.cfg/default file:

   default rhel8
   
   label rhel8
     kernel vmlinuz-kernel-version
     append initrd=initramfs-kernel-version.img root=nfs:server-ip:/exported-root-directory ro

7. Reboot the NFS server.

Procedure

1. To change the user password, follow the steps below:

   • Change the command line to /exported/root/directory:

     # chroot /exported/root/directory /bin/bash

   • Change the password for the user you want:

     # passwd <username>

     Replace the <username> with a real user to whom you want to change the password.

   • Exit the command line:

     # exit

2. To install software to a remote diskless system, use the following command:

   # yum install <package> --installroot=/exported/root/directory --releasever=/ --config /etc/dnf/dnf.conf --setopt=reposdir=/etc/yum.repos.d/

   Replace <package> with the actual package you want to install.

3. To split a remote diskless system into a /usr and a /var you must configure two separate exports. Read NFS server configuration documentation for details.

Procedure

1. From the left pane of the Manual Partitioning window, select the required partition.
2. Under the Device(s) section, click Modify. The Configure Mount Point dialog box opens.
3. Select the disks that you want to include in the RAID device and click Select.
4. Click the Device Type drop-down menu and select RAID.
5. Click the File System drop-down menu and select your preferred file system type.
6. Click the RAID Level drop-down menu and select your preferred level of RAID.
7. Click Update Settings to save your changes.
8. Click Done to apply the settings and return to the Installation Summary window.

Procedure

1. To create RAID of two block devices, for example /dev/sda1 and /dev/sdc1, use the following command:

   # mdadm --create /dev/md0 --level=<level_value> --raid-devices=2 /dev/sda1 /dev/sdc1

   Replace <level_value> to a RAID level option. For more information, see mdadm(8) man page.

2. Optionally, to check the status of RAID, use the following command:

   # mdadm --detail /dev/md0

3. Optionally, to observe the detailed information about each RAID device, use the following command:

   # mdadm --examine /dev/sda1 /dev/sdc1

4. To create a file system on a RAID drive, use the following command:

   # mkfs -t <file-system-name> /dev/md0

   where <file-system-name> is a specific file system that you chose to format the drive with. For more information, see mkfs man page.

5. To create a mount point for RAID drive and mount it, use the following commands:

   # mkdir /mnt/raid1
   # mount /dev/md0 /mnt/raid1

Procedure

1. Create a new playbook.yml file with the following content:

   - hosts: all
     vars:
       storage_safe_mode: false
       storage_volumes:
         - name: data
           type: raid
           disks: [sdd, sde, sdf, sdg]
           raid_level: raid0
           raid_chunk_size: 32 KiB
           mount_point: /mnt/data
           state: present
     roles:
       - name: rhel-system-roles.storage

   Warning

   Device names can change in certain circumstances; for example, when you add a new disk to a system. Therefore, to prevent data loss, we do not recommend using specific disk names in the playbook.

2. Optional. Verify playbook syntax.

   # ansible-playbook --syntax-check playbook.yml

3. Run the playbook on your inventory file:

   # ansible-playbook -i inventory.file /path/to/file/playbook.yml