Re: [linux-lvm] Auto PV scan w/ LVM

[David Coulson <david@davidcoulson.net>]

On 3/26/2010 12:18 PM, Mike Snitzer wrote:
> I'm not crystal clear on your use-case (e.g. the mechanics and
> constraints of when the clone is presented to the backup, etc).
>    

The process is basically this:

* Clone in 'sync' state so it is replicating block changes from the 
source. The clone LUN is still visible to the backup server, however 
both paths are 'failed' to multipathd
* We fracture/break the clone which makes the clone LUN available to the 
backup server for IO
* We mount LVs from the clone LUN on the backup server, run our backup 
job, unmount it
* vgexport the clone LUN VG and remove it from our multipath list with 
'multipath -f'
* Tell the SAN to start syncing the clone to source again until we need 
to break it for another backup.

I basically need to find a nice way to make LVM ignore the clone disk on 
the backup system until I am ready to make use of it for a backup. 
multipathd sees it as failed during this time, but vgscan/pvscan, etc 
all hang. Maybe that is normal.

> But the 'vgimportclone' command will enable you to make the cloned LUNs
> distinct from the originals.  Does this help you?
>    
The clone gets mounted on a different box to the source, so it's not 
important to me. I don't have a vgimportclone command on RHEL4, unless I 
need to install some additional packages.

David