Re: LVM snapshot

[Alexandre Oliva <aoliva redhat com>]

On Aug 18, 2004, Chris Adams <cmadams hiwaay net> wrote:

> For the same reason, I'd suggest dm-snapshot also be unconditionally
> included.  I use snapshots to get consistent backups; if the system were
> rebooted during backup (while the snapshot of / exists), I guess
> dm-snapshot is required, right?

Maybe not.  Since it's a separate LV, it's perfectly possible that, if
dm-snapshot is not available in the initrd vgscan, you won't get that
LV active, but will for the rest; later on, after the root fs is
mounted read-write, vgscan runs again, and the module is available, so
you get the snapshot volume up and running.

This is unlike dm-mirror (assuming pvmove actually uses it), since it
modifies existing volumes (e.g., the one holding the rootfs), you may
need dm-mirror early in order to boot up.

-- 
Alexandre Oliva             http://www.ic.unicamp.br/~oliva/
Red Hat Compiler Engineer   aoliva {redhat com, gcc.gnu.org}
Free Software Evangelist  oliva {lsd ic unicamp br, gnu.org}