11.4. Manual LVM Partitioning

The following section explains how to manually configure LVM for Red Hat Enterprise Linux. Because there are numerous ways to manually configure a system with LVM, the following example is similar to the default configuration done in Section 11.3, “Automatic Partitioning”.
On the Disk Partitioning Setup screen, select Create custom layout from the pulldown list and click the Next button in the bottom right corner of the screen.

11.4.1. Creating the /boot Partition

In a typical situation, the disk drives are new, or formatted clean. The following figure, Figure 11.4, “Two Blank Drives, Ready for Configuration”, shows both drives as raw devices with no partitioning configured.
Two Blank Drives, Ready for Configuration

Figure 11.4. Two Blank Drives, Ready for Configuration

Warning

The /boot partition cannot reside on an LVM volume because the GRUB boot loader cannot read it.
  1. Select New.
  2. Select /boot from the Mount Point pulldown menu.
  3. Select ext3 from the File System Type pulldown menu.
  4. Select only the sda checkbox from the Allowable Drives area.
  5. Leave 100 (the default) in the Size (MB) menu.
  6. Leave the Fixed size (the default) radio button selected in the Additional Size Options area.
  7. Select Force to be a primary partition to make the partition be a primary partition. A primary partition is one of the first four partitions on the hard drive. If unselected, the partition is created as a logical partition. If other operating systems are already on the system, unselecting this option should be considered. For more information on primary versus logical/extended partitions, refer to the appendix section of the Red Hat Enterprise Linux Installation Guide.
Refer to Figure 11.5, “Creation of the Boot Partition” to verify your inputted values:
Creation of the Boot Partition

Figure 11.5. Creation of the Boot Partition

Click OK to return to the main screen. The following figure displays the boot partition correctly set:
The /boot Partition Displayed

Figure 11.6. The /boot Partition Displayed

11.4.2. Creating the LVM Physical Volumes

Once the boot partition is created, the remainder of all disk space can be allocated to LVM partitions. The first step in creating a successful LVM implementation is the creation of the physical volume(s).
  1. Select New.
  2. Select physical volume (LVM) from the File System Type pulldown menu as shown in Figure 11.7, “Creating a Physical Volume”.
    Creating a Physical Volume

    Figure 11.7. Creating a Physical Volume

  3. You cannot enter a mount point yet (you can once you have created all your physical volumes and then all volume groups).
  4. A physical volume must be constrained to one drive. For Allowable Drives, select the drive on which the physical volume are created. If you have multiple drives, all drives are selected, and you must deselect all but one drive.
  5. Enter the size that you want the physical volume to be.
  6. Select Fixed size to make the physical volume the specified size, select Fill all space up to (MB) and enter a size in MBs to give range for the physical volume size, or select Fill to maximum allowable size to make it grow to fill all available space on the hard disk. If you make more than one growable, they share the available free space on the disk.
  7. Select Force to be a primary partition if you want the partition to be a primary partition.
  8. Click OK to return to the main screen.
Repeat these steps to create as many physical volumes as needed for your LVM setup. For example, if you want the volume group to span over more than one drive, create a physical volume on each of the drives. The following figure shows both drives completed after the repeated process:
Two Physical Volumes Created

Figure 11.8. Two Physical Volumes Created

11.4.3. Creating the LVM Volume Groups

Once all the physical volumes are created, the volume groups can be created:
  1. Click the LVM button to collect the physical volumes into volume groups. A volume group is basically a collection of physical volumes. You can have multiple logical volumes, but a physical volume can only be in one volume group.

    Note

    There is overhead disk space reserved in the volume group. The volume group size is slightly less than the total of physical volume sizes.
    Creating an LVM Volume Group

    Figure 11.9. Creating an LVM Volume Group

  2. Change the Volume Group Name if desired.
  3. All logical volumes inside the volume group must be allocated in physical extent (PE) units. A physical extent is an allocation unit for data.
  4. Select which physical volumes to use for the volume group.

11.4.4. Creating the LVM Logical Volumes

Create logical volumes with mount points such as /, /home, and swap space. Remember that /boot cannot be a logical volume. To add a logical volume, click the Add button in the Logical Volumes section. A dialog window as shown in Figure 11.10, “Creating a Logical Volume” appears.
Creating a Logical Volume

Figure 11.10. Creating a Logical Volume

Repeat these steps for each volume group you want to create.

Note

You may want to leave some free space in the volume group so you can expand the logical volumes later. The default automatic configuration does not do this, but this manual configuration example does — approximately 1 GB is left as free space for future expansion.
Pending Logical Volumes

Figure 11.11. Pending Logical Volumes

Click OK to apply the volume group and all associated logical volumes.
The following figure shows the final manual configuration:
Final Manual Configuration

Figure 11.12. Final Manual Configuration