Category: LVM

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Replace an LVM Drive with a Larger One

LVM allows you to hot add devices to expand volume space. It also allows you to hot remove devices, as long as there are enough free extents in the volume group (vgdisplay) to move data around. Here I’m going to replace a 400 GB drive (sdg) with a 750 GB one (sdh) from logical volume “backup” on volume group “disks”. It does not matter how many hard drives are in the volume group, and the filesystem can stay mounted.

  1. Partition and create a physical volume on the device 
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    $ sudo pvcreate /dev/sdh1
  2. Add the new drive to the volume group 
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    $ sudo vgextend disks /dev/sdh1
  3. Move all extents from the old drive to the new one (this step may take hours) 
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    $ sudo pvmove -v /dev/sdg1
  4. Remove the old drive 
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    $ sudo vgreduce disks /dev/sdg1
  5. Expand the logical volume to use the rest of the disk. In this case, another 350GB. 
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    $ sudo lvextend -l+83463 /dev/disks/backup
  6. Expand the file system 
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    $ sudo resize2fs /dev/disks/backup
$ sudo xfs_growfs /dev/disks/backup
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Add a Drive to an LVM Volume

This guide shows how to add a drive to an existing LVM volume.

  1. Erase the partition table on drive /dev/hdd and create the Physical volume

# dd if=/dev/zero of=/dev/hdd bs=1024k count=1
# pvcreate /dev/hdd

  1. Look at the current volume group, for fun

# sudo vgdisplay -A

— Volume group —
VG Name disks
System ID
Format lvm2
Metadata Areas 7
Metadata Sequence No 2
VG Access read/write
VG Status resizable
MAX LV 0
Cur LV 1
Open LV 1
Max PV 0
Cur PV 7
Act PV 7
VG Size 859.70 GB
PE Size 4.00 MB
Total PE 220084
Alloc PE / Size 220084 / 859.70 GB
Free PE / Size 0 / 0
VG UUID N4TcI6-DIRS-3edy-FAa0-tdUL-MTSX-bs2lJE

  1. Add the Physical Volume to the existing Volume Group, which I creatively named “disks”

# sudo vgextend disks /dev/hdd

  1. Look at the current Volume Group again, my how it has grown

# sudo vgdisplay -A

— Volume group —
-snip-
VG Size 1.11 TB
PE Size 4.00 MB
Total PE 291625
Alloc PE / Size 220084 / 859.70 GB
Free PE / Size 71541 / 279.46 GB

  1. Extend the Logical Volume, this time named “backup”, use the free extents reported by vgdisplay

# sudo lvextend -l+71541 /dev/disks/backup

Extending logical volume backup to 1.11 TB
Logical volume backup successfully resized

  1. And then look at vgdisplay again, whee

# sudo vgdisplay -A

— Volume group —
-snip-
VG Size 1.11 TB
PE Size 4.00 MB
Total PE 291625
Alloc PE / Size 291625 / 1.11 TB
Free PE / Size 0 / 0

  1. Now the final and most exciting step, expanding the filesystem. You’re using XFS right? And here’s a surprise, it should be mounted when you resize it. xfs_growfs will automatically resize the XFS filesystem to use all the available free space, and do it in less than a second.

# sudo xfs_growfs /backup