On Wed, 27 Feb 2002, Chris Mason wrote: > >> I think, the VFS patch has some principal problems. Creating > >> a snapshot > >> with the VFS-lock patch applied is more or less equivalent to > >> unmounting > >> the file system, creating the snapshot of the device and > >> remounting the > >> file system. That means that all ongoing write operations must be > >> suspended until the filesystem is in a "clean" state. This can take > >> some time. Up to 15 minutes from my observations and that is > >> way too long. > >> I think the right way is: use a jornaling file system, take a > >> snapshot, > >> make the snapshot writeable, replay the log, make the > >> snapshot readonly > >> and dump it to tape or whatever you want. No races, no deadlocks, no > >> problems. > > There is a problem with this method, namely the FS you get after > replaying the log will not be the same FS you had at the time of > the snapshot. Any transactions that had not been committed yet will > not be replayed. It will be consistent, but probably not the FS you > were expecting. It depends. For backups triggerd by cron that is not an issue, because i only expect a snapshot of the filesystem at about 2am. For other purposes it might be a problem. Would a call to sync prior to the lvcreate -s help? Anselm --- Anselm Kruis Tel. +49 (0)89-356386-74 science + computing ag FAX +49 (0)89-356386-37 Ingolstädter Str. 22 mailto: A.Kruis@science-computing.de D-80807 München WWW: http://www.science-computing.de/ ********************************************************************** *** Wir freuen uns auf Ihren Besuch *** *** *** *** CeBIT 2002 *** *** 13.-20.03.2002, Messegelände Hannover, Halle 11, F 64 *** *** *** *** Automotive Circle International *** *** 18.-19.04.2002, Bad Nauheim *** *** *** *** VDI-Tagung: Berechnung und Simulation im Fahrzeugbau *** *** 01.-02.10.2002, Congress-Centrum Würzburg *** *** *** ********************************************************************** _______________________________________________ linux-lvm mailing list linux-lvm@sistina.com http://lists.sistina.com/mailman/listinfo/linux-lvm read the LVM HOW-TO at http://www.sistina.com/lvm/Pages/howto.html
