Expanding an LVM Swap Volume

The following procedure applies to expanding an LVM swap volume only. If you want to expand a LVM root or data volume, see Expanding an LVM Data or Root Volume. If you want to expand a Linux root or data partition that is not managed by LVM, see Expanding a Root Partition and Expanding a Linux Data Partition.

Before You Begin

Make sure you know the name of the LVM swap volume and the KeyControl clear text path to it. If you do not, use the hcl status command and look at the Registered Devices section. For example:

# hcl status
...

Registered Devices
--------------------------------------------------------------------------------
Disk Name            Cipher       Status                  Clear 
--------------------------------------------------------------------------------
cl_centos73-swap    AES-XTS-512  Attached               /dev/mapper/clear_htswap (swap)
 '--> auto_attach=ENABLED, attach_handler=DEFAULT, detach_handler=DEFAULT
cl_centos73-root       AES-XTS-512  Attached                /dev/mapper/clear_htroot (/)
 '--> auto_attach=ENABLED, attach_handler=DEFAULT, detach_handler=DEFAULT

Procedure

Log into the VM as root.

Get the UUID of the swap device by using the blkid swap-clear-text-path command. For example:

# blkid /dev/mapper/clear_htswap
/dev/mapper/clear_htswap: UUID="a949b636-1669-43cb-acc4-b1ed86e7f2f1 TYPE="swap"

Turn the swap off by entering the command swapoff -a.
```
# swapoff -av
swapoff on /dev/mapper/clear_htswap
```
Tip: If the swapoff command does not work, applications are probably using the swap file. You can make a temporary swap space and move the swap there until this procedure is finished. For example:
```
# fallocate --length 2GiB /swapfile
# mkswap /swapfile
# swapon /swapfile
```
You can also try stopping all main applications and then dropping all caches from memory. For details, see your Linux documentation.
Increase the size the LVM swap volume as desired using the lvresize diskname command, where diskname is the name of the swap volume . For example, if you want to increase the swap volume cl_centos73-swap by 256M, you would enter:
```
# lvm lvresize /dev/cl_centos73/swap -L +256M
  Size of logical volume cl_centos73/swap changed from 1.00 GiB (256 extents) to 1.25 GiB (320 extents).
  Logical volume cl_centos73/swap successfully resized.
```
Increase the size of the encrypted swap to match the new volume size. How you do this depends on whether Online Encryption is enabled or disabled for the volume.

Tip: You can always use the Offline Resize Method for swap volumes regardless of whether they use Online Encryption. If you are not sure whether Online Encryption is enabled on the volume, use the Offline Resize Method.

Select one of the following methods:
- Online Resize Method — Usable for swap volumes only if Online Encryption is disabled.
  
  Use the command hcl resize diskname, where diskname is the name of the swap volume.
```
# hcl resize cl_centos73-swap
Warning: Resizing active device incorrectly can cause any data stored on them to become
inaccessible
Do you want to proceed? (y/n) y
Device cl_centos73-swap was successfully resized
Updating the KC with the size (1310720 KB) of the device
Successfully updated the KC with size (1310720 KB) of the device cl_centos73-swap
```
- Offline Resize Method — Usable for all swap volumes. This method is required for swap volumes on which Online Encryption is enabled.
  
  Reboot the VM.
  
  # reboot

Re-create swap on the swap volume using the mkswap -U clear-text-path command, where clear-text-path is the clear text path to the swap volume. For example, if the clear text path is /dev/mapper/clear_htswap, you would enter:

# mkswap -U "a949b636-1669-43cb-acc4-b1ed86e7f2f1" /dev/mapper/clear_htswap
mkswap: /dev/mapper/clear_htswap: warning: wiping old swap signature.
Setting up swapspace version 1, size = 1310716 KiB
no label, UUID=a949b636-1669-43cb-acc4-b1ed86e7f2f1

Turn the swap back on using the swapon -va command. For example:

# swapon -va
swapon /dev/mapper/clear_htswap
swapon: /dev/mapper/clear_htswap: found swap signature: version 1, page-size 4, same byte
order
swapon: /dev/mapper/clear_htswap: pagesize=4096, swapsize=1342177280, devsize=1342177280


# swapon --show
NAME TYPE SIZE USED PRIO
/dev/dm-4 partition 1.3G 0B -1