topic Single LUN mirroring within a VG in Operating System - Linux

Single LUN mirroring within a VG

MonitKapoor — Mon, 04 Feb 2008 22:04:03 GMT

I have a VG which consists of 5 x 1.35TB Clariion LUNS. I was informed by the Storage team that one of these luns was experiencing parity errors for a while and the only way to correct is to relocate data elsewhere(maybe tape) and recreate the VG. This is not practicle due to the size invovled and the criticality of data.

Is it possible,that if they were to provide me with another 1.35 TB LUN, that i could mirror the problematic LUN on this and detach the bad lun?

The current probematic lun looks like this:
pvdisplay --- Physical volume ---
pvdisplay PV Name /dev/sdd1
pvdisplay VG Name vg1
pvdisplay PV Size 1.35 TB / not usable 0
pvdisplay Allocatable yes (but full)
pvdisplay PE Size (KByte) 4096
pvdisplay Total PE 354814
pvdisplay Free PE 0
pvdisplay Allocated PE 354814
pvdisplay PV UUID PvrSu9-NTgI-iZnZ-Xwi1-a6y1-12It-6wwKpT

Re: Single LUN mirroring within a VG

Stuart Browne — Mon, 04 Feb 2008 22:52:03 GMT

Mirror? Well, not really; but you can migrate the data off the LUN onto the newly added space.

'pvmove' is your friend. 'vgextend' your volume group to include the new LUn, then 'pvmove' the data, followed by 'vgreduce' to remove the old LUN.

See http://tldp.org/HOWTO/LVM-HOWTO/removeadisk.html for exact details, in particular 13.5.2.

Re: Single LUN mirroring within a VG

skt_skt — Mon, 04 Feb 2008 23:44:05 GMT

We do vgextend & lvextend(-m 1) and once the mirror synced do the lvreduce (-m 0) and do vgreduce.. similar procedure works well with HP-UX.. Not really done on Linux.

lvextend/lvreduce are aplicable to all the lvol where the defective device is in use.