[dm-devel] Re: [PATCH 3/3] Add timeout feature
Miklos Szeredi
miklos at szeredi.hu
Wed Jul 9 06:48:42 UTC 2008
On Tue, 8 Jul 2008, Arjan van de Ven wrote:
> nah he needs to do
>
> make_snapshot ; backup-command ; unref_snapshot.
>
> freezing isn't the right solution for the backup problem ;)
Confused, what's freezing _is_ for then? Patch description says:
Currently, ext3 in mainline Linux doesn't have the freeze feature which
suspends write requests. So, we cannot take a backup which keeps
the filesystem's consistency with the storage device's features
(snapshot and replication) while it is mounted.
In many case, a commercial filesystem (e.g. VxFS) has
the freeze feature and it would be used to get the consistent backup.
If Linux's standard filesytem ext3 has the freeze feature, we can do it
without a commercial filesystem.
Miklos
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