6.13.1.2 Expanding Swap Space on a Guest Using Exascale Storage

You can expand the disk space on an Oracle Linux KVM guest that uses an Exascale system volume, then use the added capacity to create and enable additional swap space.

This procedure follows the same general flow as the related Oracle Exadata procedure for expanding guest disk space backed by Exascale storage: identify the guest disk, expand the Exascale volume, resize the disk visible to the running guest, update the guest partition and LVM physical volume, then verify the result.

  1. On the KVM host, identify the Exascale system volume used by the guest.

    Run the following command on the KVM host, specifying the name of the guest that you want to modify. In this example, the guest domain name is exa01adm01vm01.example.com. 

    [root@exa01adm01 ~]# vm_maker --list --disk-image --domain exa01adm01vm01.example.com --detail
Type   Path                                                                  Target
Block  /dev/exc/exa01adm01vm01_sys_vol0019_acb70712ce824e8fbfef0205a05dd5fc  sda
...

    In the output, locate on the system volume, which contains _sys_ in the disk device name. Take note of the following information, which you will require throughout the rest of the procedure:

    • The guest disk target name (sda).

    • The Exascale disk device path (/dev/exc/exa01adm01vm01_sys_vol0019_acb70712ce824e8fbfef0205a05dd5fc).

    • The disk image name embedded in the device path (exa01adm01vm01_sys_vol0019_acb70712ce824e8fbfef0205a05dd5fc).

    • The Exascale volume ID embedded in the device path (vol0019_acb70712ce824e8fbfef0205a05dd5fc).

    Note:

    The command examples in the rest of this procedure use the example values shown in this step. Ensure that you replace these values with your own as needed when running the commands.

  2. On the KVM host, confirm the current disk size.

    Run the following commands and confirm that the outputs show the same current disk size (in bytes).

    [root@exa01adm01 ~]# virsh domblkinfo exa01adm01vm01.example.com sda
Capacity:       109521666048
Allocation:     104065961984
Physical:       109521666048

[root@exa01adm01 ~]# blockdev --getsize64 /dev/exc/exa01adm01vm01_sys_vol0019_acb70712ce824e8fbfef0205a05dd5fc
109521666048
  3. In Exascale, verify and expand the volume.
    1. Connect to the Exascale command line interface (ESCLI) as the storage administrator or volume owner.
    2. Confirm the current size of the Exascale volume.

      For example:

      @>lsvolume vol0019_acb70712ce824e8fbfef0205a05dd5fc --attributes id,name,size,state
id                                       name                       size state
vol0019_acb70712ce824e8fbfef0205a05dd5fc exa01adm01vm01_sys    102.0000G AVAILABLE

      Note:

      109521666048 bytes = 102 GB

    3. Expand the Exascale volume.

      For example, the following command sets the volume size to 120 GB.

      @>chvolume vol0019_acb70712ce824e8fbfef0205a05dd5fc --attributes size=120G
Volume altered.
  4. Resize the disk on the KVM host.

    On the KVM host, run the vm_maker command with the --resize option. Identify the disk (--disk) using the disk image name observed on the KVM host and specify the guest name (--domain).

    For example:

    [root@exa01adm01 ~]# vm_maker --resize --disk exa01adm01vm01_sys_vol0019_acb70712ce824e8fbfef0205a05dd5fc --domain exa01adm01vm01.example.com
[INFO] Running 'virt-control blockresize exa01adm01vm01.example.com /dev/exc/exa01adm01vm01_sys_vol0019_acb70712ce824e8fbfef0205a05dd5fc 128849018880B'...
[INFO] Disk image /dev/exc/exa01adm01vm01_sys_vol0019_acb70712ce824e8fbfef0205a05dd5fc resized to 120G
  5. In the guest, expand the system volume.

    Use the following command sequence, substituting in your earlier gathered device details.

    1. Examine the system disk and confirm its size.
      [root@exa01adm01vm01 ~]# lsblk -o NAME,TYPE,SIZE,FSTYPE,LABEL,MOUNTPOINT /dev/sda
NAME                           TYPE  SIZE FSTYPE      LABEL MOUNTPOINT
sda                            disk  120G
|-sda1                         part  512M xfs         BOOT  /boot
|-sda2                         part  256M
`-sda3                         part 98.6G LVM2_member
  |-VGExaDb-LVDbSys1           lvm    15G xfs         DBSYS /
  |-VGExaDb-LVDbVar1           lvm     2G xfs         VAR   /var
  |-VGExaDb-LVDbVarLog         lvm    18G xfs         DIAG  /var/log
  |-VGExaDb-LVDbHome           lvm     4G xfs         HOME  /home
  |-VGExaDb-LVDbSys2           lvm    15G xfs
  |-VGExaDb-LVDbSwap1          lvm    16G swap        SWAP  [SWAP]
  |-VGExaDb-LVDbTmp            lvm     3G xfs         TMP   /tmp
  |-VGExaDb-LVDbVar2           lvm     2G xfs
  |-VGExaDb-LVDbVarLogAudit    lvm     1G xfs         AUDIT /var/log/audit
  |-VGExaDb-LVDbKdump          lvm    20G xfs         KDUMP /crashfiles
  `-VGExaDb-LVDoNotRemoveOrUse lvm   2.6G

      At this point, the disk (sda) should reflect the updated size (120G), but the LVM partition (sda3) has not been expanded to use the added space.

    2. Determine if the device uses a GUID Partition Table (GPT) and update it if necessary.

      • Run the following command to determine if the device uses GPT:

        [root@exa01adm01vm01 ~]# blkid -o value -s PTTYPE /dev/sda
gpt

        If the command output indicates that the device does not use GPT, skip to "Extend the LVM partition into the expanded device space."

      • If output of the previous command indicates that the device uses GPT, run the following commands to update the partition view in the OS kernel:

        [root@exa01adm01vm01 ~]# printf "Fix\nYes\n" | parted ---pretend-input-tty /dev/sda print
Warning: Not all of the space available to /dev/sdd appears to be used, 
you can fix the GPT to use all of the space
...

[root@exa01adm01vm01 ~]# partprobe /dev/sda
    3. Extend the LVM partition into the expanded device space:
      [root@exa01adm01vm01 ~]# parted -s /dev/sda "resizepart 3 100%"
    4. Ensure that the OS kernel is aware of the partition change.
      [root@exa01adm01vm01 ~]# partprobe /dev/sda
[root@exa01adm01vm01 ~]# partx -u /dev/sda
    5. Resize the physical volume:
      [root@exa01adm01vm01 ~]# pvresize /dev/sda3
  Physical volume "/dev/sda3" changed
  1 physical volume(s) resized or updated / 0 physical volume(s) not resized
    6. Verify the free space now available in the LVM partition:
      [root@exa01adm01vm01 ~]# pvs -o pv_name,vg_name,pv_size,pv_free
  PV         VG                                                                           PSize      PFree
  /dev/sda3  VGExaDb                                                                      <98.55g  <18.00g
  ...
  6. In the guest, expand the swap by adding another swap logical volume.

    Note:

    This procedure expands swap space by adding another logical volume. This approach avoids a scheduled maintenance period and reduces the risk of disrupting workloads in the guest.

    Alternatively, you can expand the existing swap device. However, that approach requires taking the existing swap device offline, which may disrupt workloads in the guest.

    1. Back up the volume group metadata before creating the new logical volume.
      [root@exa01adm01vm01 ~]# vgcfgbackup VGExaDb
  Volume group "VGExaDb" successfully backed up.
    2. Create the new swap logical volume.

      In this example, the size of the new swap logical volume is 16 GB.

      [root@exa01adm01vm01 ~]# lvcreate -n LVDbSwap2 -L 16G VGExaDb
  Logical volume "LVDbSwap2" created.
    3. Initialize the logical volume as swap and assign the label SWAP2.
      [root@exa01adm01vm01 ~]# mkswap -L SWAP2 /dev/VGExaDb/LVDbSwap2
Setting up swapspace version 1, size = 16 GiB (17179869184 bytes)
LABEL=SWAP2, UUID=63825008-90f2-4448-91b4-1ced8a0207c0
    4. Enable the new swap device immediately.
      [root@exa01adm01vm01 ~]# swapon -L SWAP2
  7. In the guest, persist the new swap device.
    1. Back up /etc/fstab.
      [root@exa01adm01vm01 ~]# cp -p /etc/fstab /etc/fstab.pre_swap2
    2. Add the new swap entry.
      [root@exa01adm01vm01 ~]# echo "LABEL=SWAP2 swap swap defaults 0 0" >> /etc/fstab
    3. Reload the systemd manager configuration.
      [root@exa01adm01vm01 ~]# systemctl daemon-reload
  8. Verify the final configuration.
    1. Verify that both swap devices are active.
      [root@exa01adm01vm01 ~]# swapon --show
NAME       TYPE      SIZE USED PRIO
/dev/dm-8  partition  16G   0B   -2
/dev/dm-14 partition  16G   0B   -3
    2. Verify the swap logical volumes.
      [root@exa01adm01vm01 ~]# lvs VGExaDb | grep Swap
  LVDbSwap1          VGExaDb -wi-ao---- 16.00g
  LVDbSwap2          VGExaDb -wi-ao---- 16.00g
    3. Verify the persistent swap entries in /etc/fstab.
      [root@exa01adm01vm01 ~]# grep -n swap /etc/fstab
3:LABEL=SWAP   swap swap defaults 0 0
14:LABEL=SWAP2 swap swap defaults 0 0

Parent topic: Increasing the Disk Space in a Guest Using Exascale Storage