Re: snapshot merging?

[Eric Anopolsky <erpo41@gmail.com>]

[-- Attachment #1: Type: text/plain, Size: 1143 bytes --]

On Tue, 2008-09-23 at 20:34 -0700, Daniel Phillips wrote:
> On Sunday 21 September 2008 07:31, Tomasz Chmielewski wrote:
> > > Writeable snapshot has been available in btrfs for a long time.
> > 
> > Writeable snapshots and snapshot merging are two different things.
> 
> I think what Mikulas really means by "snapshot merging" is what we call
> "revert to snapshot" in ddsnap (google Zumastor ddsnap).  The latter is
> more appropriate terminology IMHO.  For a snapshotted volume, this just
> requires copying any blocks that belong to the snapshot and not the
> origin back to the origin.  Similarly, one could revert any snapshot
> "back" (quotes because there is not necessarily any relationship in
> time) to any other.  For a filesystem it will not be nearly so simple,
> because at best only part of the job can be done at the physical block
> level.

It took me a while to get what was meant by snapshot merging. Consider
this a vote for the "revert" terminology. :) Although, it calls into
question some of my assumptions about what people use snapshots for.

What do people use snapshots for?

Cheers,
Eric


[-- Attachment #2: This is a digitally signed message part --]
[-- Type: application/pgp-signature, Size: 189 bytes --]