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

[Jonathan Brassow]

you will need more than on device in your volume group.  Example:
$> pvcreate /dev/sd[ab]
$> vgcreate vg /dev/sd[ab]
$> lvcreate -n lv -L 200G vg /dev/sda
$> lvcreate -s -n snap -L 20G vg/lv /dev/sdb

The cow will be located on sdb, while the origin will be located on sda.

  brassow

On Aug 27, 2007, at 3:53 AM, Hannes Dorbath wrote:

> Hello,
>
> 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.
>
>
> -- 
> Regards,
> Hannes Dorbath
>
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