KB450034 – How can I grow my mdadm RAID and LVM

Last modified: January 24, 2019
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Extending an mdadm RAID and then growing your LVM can be done in a few simple steps, but you’ll need to set aside some time to allow the RAID to re-sync.

Below are the steps that were taken to grow a 6 drive RAID6 with XFS, to a 9 drive RAID6 and then growing our LVM from 100Gb to 1000Gb.

1. Add 3 more drives to the RAID

  * 'mdadm --add /dev/md0 /dev/sd[ghi]'  (where /dev/md0 is the RAID, and /dev/sd[ghi] are the 3 drives being added)
  * 'mdadm --grow --raid-devices=9 /dev/md0'
  * This process was rather slow (~500-600 minutes) 

2. Resize the Physical Volume

  * 'pvresize /dev/md0'

3. Resize the Logical Volume

  * 'lvextend -L +X /dev/lvm/root' (where X is the amount of space to be added, and /dev/lvm/root is the location of the Logical Volume)

4. Mount the volume

  * 'mount -t xfs /dev/lvm/root /Volume' (where /Volume is the mount point for our logical volume)

5. Extend the filesystem to include the added space

  * 'xfs growfs /Volume'

6. Check to see that the mounted volume is now updated

  * 'df -h'
  * This should result in showing your volume mounted at your chosen mount point with the additional space added.

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