Re: device mapper help

["hhding.gnu" <hhding.gnu@gmail.com>]

William Thompson wrote:
> I'm not on the list.  Please always keep me in the CC.
> 
> Is there a tool somewhere that will allow me to merge a snapshot into the
> parent device?
> 
> For instance, if I have a snapshot of /dev/sdb like this:
> sdb-snap1: 0 16777216 snapshot /dev/sdb /dev/sdb-snap1-backing P 8
> sdb-snap2: 0 16777216 snapshot /dev/sdb-snap1 /dev/sdb-snap2-backing P 8
> ...
> 
> Lets say that I want to update sdb with the data in /dev/sdb-snap1-backing. 
> What would I do to do this?  Is there some tool that does this?  I
> understand that there can be problems with snapshots of snapshots like this,
> but that is not the question.
> 
> 
As far as I know, LVM does not provide this function. ZFS can promote
it's snapshoot.

Regards,
Ding Honghui