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KB450034 – Extending mdadm RAID and LVM

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This article details the process of extending your mdadm raid and LVM


Already preconfigured mdadm raid on a 45 Drives unit


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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