lvreduce bad extents in the middle of an lvol?

[Todd McDaniel_1]

Short story.

I have a bad disk that I was able to move out of the Lvol by doing a vgscan.

However, now I have ??? extents in the middle of my Lvol. Should I just blow it away and rebuild it? then restore the data...

OR is there a way to remove bad extents in the middle of a Lvol? Does Lvreduce allow for that or does it only remove extents from the end of the Lvol?

[James R. Ferguson · Accepted solution]

Hi Todd:

Unless this is a mirrored logical volume, you will need to rebuild it on a sound physical disk and restore its data.

The 'lvreduce' removed extents from the end of a logical volume. The 'lvreduce -k' reduces a mirrored logical volume on a physical volume that has failed or is missing.

Regards!

...JRF...

[Todd McDaniel_1]

I think I will have to destroy the LVOL, b/c it is still confusing the kernel, which shows 17 disks for the VG, even though the VG only shows 16 disks.

[Sandman!]

The ??? PEs come from the missing disk, and so is the discrepancy between Cur PV and Act PV. You might have to do the following:

- use lvremove to remove the erroneous lvol.
- force the bad PV out of the VG by doing "vgreduce -f /dev/vg_name"
(this should make Cur PV = Act PV).
- recreate the lvol and restore the data onto it.

Make sure you have good backups of the data and metadata (vgcfgbackup) before you try this.

~hope it helps

[James R. Ferguson]

Hi (again) Todd:

You should read (it's short) this whitepaper:

http://www.docs.hp.com/en/5991-1236/When_Good_Disks_Go_Bad.pdf

Regards!

...JRF...