LVM - Remove a disk

Hello,

I need to remove 1 of 3 disks from a Logical Volume. Following the standard pvmove commands I noticed that even though there is plenty of free space over the remaining extents all 3 disks are showing 100% full in LVM (both at the CLI and inside OMV).

Is there something odd with the way OMV sets out its file system on the Logical Volume which makes LVM think the disks are 100% utilized?

Many thanks.

Edit: To add a bit more info here. In the LVM section on OMV I see that the 3 Physical Disks are showing 100% used and the single Volume Group is showing 0Mb Free. The only area which says shows free space is the OMV File Systems section. About 50% used. The File System is Ext4.

Thanks again!

Thanks David,

I need to unmount the disk before I can reduce the size. In the gui I can see no way to do this without deleting all shares using the folders on the filesystem (i.e. so that those folders turned to 'not in use').

Is it safe to bypass all this and unmount via the command line? It seems a bit crazy to have to unshare everything. I thought just turning off the CIFS service would have been enough but its still grey'd out.

Zitat von "davidh2k"

You need to shrink the filesystem before you can remove the disk from the lvm. This is not possible via WebGUI, you need to do it via CLI or use a parted magic/gparted live cd.

Greetings
David

I've now reduced the size of the Ext4 filesystem enough to in theory pvmove out the offending disc. The change was successful in that the capacity of the file system is reduced to very close to the size of the data sitting on it.

However I still get the message 'No extents available for allocation' and a pvscan shows all discs to be fully utilised.

I'm now wondering if i'm meant to reduce the size of the Logical Volume as well?

Right all sorted.

For the record and others wanting to remove a physical disk from an OMV install which leverages LVM, these are the high level steps I had to take.

Sizes may not be exact as I documented this after the fact and so lost some of the exact numbers

MAKE SURE YOU HAVE A FULL BACKUP BEFORE DOING THIS

Note: In OMV the file system uses the mapper feature. usually the fs is /dev/mapper/[filesystem name]

Working Example: 3 HDs. 1 Volume Group. 1 File system.
root@NAS:~# pvscan
PV /dev/sdb VG data lvm2 [931.51 GiB / 0 free]
PV /dev/sdc VG data lvm2 [931.51 GiB / 0 free]
PV /dev/sdd VG data lvm2 [1.82 TiB / 0 free]

Ext4 File system 'data' 3.18TB. Datasize 1.8TB

Task: Remove /dev/sdb

Steps:
Unmount the file system
root@NAS:~# umount /dev/mapper/data

Check file system
root@NAS:~# fsck -f /dev/mapper/data

Reduce the file systems size to 2100G (leaving room for the 1.8TB of data)
root@NAS:~# resize2fs /dev/mapper/foo 2100G

Check file system
root@NAS:~# fsck -f /dev/mapper/data

Reduce Volume Group size to a few Gigabytes bigger than 2.1TB filesystem size
root@NAS:~# vgreduce -F 2110G

Check file system
root@NAS:~# fsck -f /dev/mapper/data

Resize file system to fill the volume group size
root@NAS:~# resize2fs /dev/mapper/data

Scan again for results
root@NAS:~# pvscan
PV /dev/sdb VG data lvm2 [931.51 GiB / 0 free]
PV /dev/sdc VG data lvm2 [931.51 GiB / 0 free]
PV /dev/sdd VG data lvm2 [1.82 TiB / 92.49 GiB free]

pvmove contents of the disk needing removal
root@NAS:~# pvmove /dev/sdb

Remove the disk from the volume group
root@NAS:~# vgreduce data /dev/sdb

Scan to check results
root@NAS:~# pvscan
PV /dev/sdc VG data lvm2 [931.51 GiB / 0 free]
PV /dev/sdd VG data lvm2 [1.82 TiB / 92.49 GiB free]
PV /dev/sdb lvm2 [931.51 GiB]

In the OMV GUI the Delete button for /dev/sdb in LVM is now un-grey'd. click it to remove the disk from the LMV.

You are now free to remove the physical disk from your box.