[dm-devel] Re: [PATCH v3 00/12] snapshot-merge target

[Mike Snitzer <snitzer redhat com>]

On Thu, Nov 19 2009 at  6:25am -0500,
Andi Kleen <andi firstfloor org> wrote:

> Mike Snitzer <snitzer redhat com> writes:
> 
> > snapshot-merge target, quilt tree is maintained here:
> > http://people.redhat.com/msnitzer/patches/snapshot-merge/kernel/2.6.33/
> 
> It might seem trivial to you, but afaik nothing in the whole series
> (nor in the comments in the code) says what snapshot merging
> actually is. Please write meaningful changelogs and comments.

OK, I hadn't noticed because I was so focused on the details.

DM (and LVM) snapshot merging allows a snapshot (its COW store) to be
merged back into the snapshot's origin device.

One expected use of snapshot merging is rollback of a root filesystem
after system upgrades (e.g.: yum update).

Mike