Chapter 17. Managing Redundant Arrays of Independent Disks in the web console

Redundant Arrays of Independent Disks (RAID) represents a way how to arrange more disks into one storage. RAID protects data stored in the disks against disk failure.

RAID uses the following data distribution strategies:

  • Mirroring — data are copied to two different locations. If one disk fails, you have a copy and your data is not lost.
  • Striping — data are evenly distributed among disks.

Level of protection depends on the RAID level.

The RHEL web console supports the following RAID levels:

  • RAID 0 (Stripe)
  • RAID 1 (Mirror)
  • RAID 4 (Dedicated parity)
  • RAID 5 (Distributed parity)
  • RAID 6 (Double Distributed Parity)
  • RAID 10 (Stripe of Mirrors)

Before you can use disks in RAID, you need to:

  • Create a RAID.
  • Format it with file system.
  • Mount the RAID to the server.

Prerequisites

17.1. Creating RAID in the web console

Configure RAID in the RHEL 8 web console.

Prerequisites

  • Physical disks connected to the system. Each RAID level requires different amount of disks.

Procedure

  1. Open the RHEL 8 web console.
  2. Click Storage.
  3. Click the + icon in the RAID Devices box.

    cockpit raid add

  4. In the Create RAID Device dialog box, enter a name for a new RAID.
  5. In the RAID Level drop-down list, select a level of RAID you want to use.
  6. In the Chunk Size drop-down list, leave the predefined value as it is.

    The Chunk Size value specifies how large is each block for data writing. If the chunk size is 512 KiB, the system writes the first 512 KiB to the first disk, the second 512 KiB is written to the second disk, and the third chunk will be written to the third disk. If you have three disks in your RAID, the fourth 512 KiB will be written to the first disk again.

  7. Select disks you want to use for RAID.

    cockpit raid create

  8. Click Create.

In the Storage section, you can see the new RAID in the RAID devices box and format it.

cockpit raid created

Now you have the following options how to format and mount the new RAID in the web console:

17.2. Formatting RAID in the web console

Format the new software RAID device created in the RHEL 8 web interface.

Prerequisites

  • Physical disks are connected and visible by RHEL 8.
  • RAID is created.
  • Consider the file system which will be used for the RAID.
  • Consider creating of a partitioning table.

Procedure

  1. Open the RHEL 8 web console.
  2. Click Storage.
  3. In the RAID devices box, choose the RAID you want to format by clicking on it.
  4. In the RAID details screen, scroll down to the Content part.
  5. Click to the newly created RAID.

    cockpit raid unrecognized

  6. Click the Format button.
  7. In the Erase drop-down list, select:

    • Don’t overwrite existing data — the RHEL web console rewrites only the disk header. Advantage of this option is speed of formatting.
    • Overwrite existing data with zeros — the RHEL web console rewrites the whole disk with zeros. This option is slower because the program has to go through the whole disk. Use this option if the RAID includes any data and you need to rewrite it.
  8. In the Type drop-down list, select a XFS file system, if you do not have another strong preference.
  9. Enter a name of the file system.
  10. In the Mounting drop down list, select Custom.

    The Default option does not ensure that the file system will be mounted on the next boot.

  11. In the Mount Point field, add the mount path.
  12. Select Mount at boot. cockpit raid format
  13. Click the Format button.

    Formatting can take several minutes depending on the used formatting options and size of RAID.

    After successful finish, you can see the details of the formatted RAID on the Filesystem tab.

    cockpit raid formatted

  14. To use the RAID, click Mount.

At this point, the system uses mounted and formatted RAID.

17.3. Using the web console for creating a partition table on RAID

Format RAID with the partition table on the new software RAID device created in the RHEL 8 web interface.

RAID requires formatting as any other storage device. You have two options:

  • Format the RAID device without partitions
  • Create a partition table with partitions

Prerequisites

  • Physical disks are connected and visible by RHEL 8.
  • RAID is created.
  • Consider the file system used for the RAID.
  • Consider creating a partitioning table.

Procedure

  1. Open the RHEL 8 web console.
  2. Click Storage.
  3. In the RAID devices box, select the RAID you want to edit.
  4. In the RAID details screen, scroll down to the Content part.
  5. Click to the newly created RAID.

    cockpit raid unrecognized

  6. Click the Create partition table button.
  7. In the Erase drop-down list, select:

    • Don’t overwrite existing data — the RHEL web console rewrites only the disk header. Advantage of this option is speed of formatting.
    • Overwrite existing data with zeros — the RHEL web console rewrites the whole RAID with zeros. This option is slower because the program has to go through the whole RAID. Use this option if RAID includes any data and you need to rewrite it.
  8. In the Partitioning drop-down list, select:

    • Compatible with modern system and hard disks > 2TB (GPT) — GUID Partition Table is a modern recommended partitioning system for large RAIDs with more than four partitions.
    • Compatible with all systems and devices (MBR) — Master Boot Record works with disks up to 2 TB in size. MBR also support four primary partitions max.

      cockpit raid partition table

  9. Click Format.

At this point, the partitioning table has been created and you can create partitions.

For creating partitions, see Using the web console for creating partitions on RAID.

17.4. Using the web console for creating partitions on RAID

Create a partition in the existing partition table.

Prerequisites

Procedure

  1. Open the RHEL 8 web console.
  2. Click Storage.
  3. In the RAID devices box, click to the RAID you want to edit.
  4. In the RAID details screen, scroll down to the Content part.
  5. Click to the newly created RAID.
  6. Click Create Partition.
  7. In the Create partition dialog box, set up the size of the first partition.
  8. In the Erase drop-down list, select:

    • Don’t overwrite existing data — the RHEL web console rewrites only the disk header. Advantage of this option is speed of formatting.
    • Overwrite existing data with zeros — the RHEL web console rewrites the whole RAID with zeros. This option is slower because the program have to go through the whole RAID. Use this option if RAID includes any data and you need to rewrite it.
  9. In the Type drop-down list, select a XFS file system, if you do not have another strong preference.
  10. Enter any name for the file system. Do not use spaces in the name.
  11. In the Mounting drop down list, select Custom.

    The Default option does not ensure that the file system will be mounted on the next boot.

  12. In the Mount Point field, add the mount path.
  13. Select Mount at boot.
  14. Click Create partition.

    cockpit raid partition create

Formatting can take several minutes depending on used formatting options and size of RAID.

After successful finish, you can continue with creating other partitions.

At this point, the system uses mounted and formatted RAID.

17.5. Using the web console for creating a volume group on top of RAID

Build a volume group from software RAID.

Prerequisites

  • RAID device, which is not formatted and mounted.

Procedure

  1. Open the RHEL 8 web console.
  2. Click Storage.
  3. Click the + icon in the Volume Groups box.
  4. In the Create Volume Group dialog box, enter a name for the new volume group.
  5. In the Disks list, select a RAID device.

    If you do not see the RAID in the list, unmount the RAID from the system. The RAID device must not be used by the RHEL 8 system.

    cockpit raid vg

  6. Click Create.

The new volume group has been created and you can continue with creating a logical volume.

cockpit raid vg created