[linux-lvm] How do you mount a snapshot?

David Gould dg at suse.com
Fri Dec 8 18:30:07 UTC 2000

On Fri, Dec 08, 2000 at 09:09:57AM -0500, Chris Mason wrote:
> On Thursday, December 07, 2000 22:33:00 -0800 David Gould <dg at suse.com>
> wrote:
> > On Thu, Dec 07, 2000 at 03:56:11PM -0500, Chris Mason wrote:
> [ snapshots ]
> >> It should work with ext2.
> > 
> > Really? I wonder. Maybe right after a sync before anything gets dirtied,
> > but otherwise, how could the disk image be consistantly, er, consistant?
> > And would not e2fsck have the same issues about writing?
> > 
> > Or did I just wake up pessimistic today?
> > 
> The reason it will not work on reiserfs without the extra API is that on
> reiserfs, sync == commit to log, not commit to disk.  So, there is no way
> over the command line (or in the kernel) to ask the FS to sync to disk,
> even when there is no traffic at all on the FS.
> With ext2, if nothing is going on, you can type sync and have all the
> buffers on disk.  It is at least possible ;-)  It would be better if ext2
> could provide the write suspension hooks as well, but I'm guessing that
> will be done in ext3 first (where the journal already does most of the
> work).

Ok, so we are agreeing, it does not work on ext2 either unless you sync
and do not write between the sync and the snapshot. Doable, but not exactly

David Gould                                                 dg at suse.com
SuSE, Inc.,  580 2cd St. #210,  Oakland, CA 94607          510.628.3380
"As I've gained more experience with Perl it strikes me that it
 resembles Lisp in many ways, albeit Lisp as channeled by an awk
 script on acid."  -- Tim Moore <moore at herschel.bricoworks.com>,
                      on comp.lang.lisp

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