[linux-lvm] Snapshot COW area on different PV / device

Hannes Dorbath light at theendofthetunnel.de
Mon Aug 27 08:53:33 UTC 2007


I suffer from massive I/O trashing, due to the snapshot COW area being 
located on the same physical device as the origin. The machine now has a 
second disk array, that I'd like to dedicate to snapshot COW data. My 
problem now is that I fail to see from the documentation how to create a 
snapshot, which has its COW area located on another device. The setup 
currently looks like:

VG     #PV #LV #SN Attr   VSize   VFree
data     1   1   0 wz--c- 437.62G      0
cow1     1   0   0 wz--c- 232.82G 232.82G
cow2     1   0   0 wz--c- 232.82G 232.82G

LV     VG     Attr   LSize   Origin Snap%  Move Log Copy%
data   data   -wc-ao 437.62G

data is the LV where production data is located, and the cow1 and cow2 
VGs should be used for snapshots. Can someone give me an example on the 
lvcreate syntax to archive this? I tried various things, but end up with 
error messages like "Could not fine LV <foo> in PV <bar>".

Thanks in advance.

Hannes Dorbath

More information about the linux-lvm mailing list