On Mon, Aug 4, 2008 at 4:15 PM, Mikulas Patocka <mpatocka@xxxxxxxxxx> wrote: > On Fri, 1 Aug 2008, Adam Hamsik wrote: > >> On Aug,Friday 1 2008, at 9:35 AM, Bombardier, Pascal wrote: >> >> > Hi, >> > >> > In your opinion, does it make sense to be able to create non-persistent >> > snapshots ? >> > In the case of a filesystem backup, a non-persistent snapshot would be a >> > snapshot that we agree to lose in case of failure or reboot. If anything >> > happens, a server administrator would have to recreate a new snapshot >> > and then restart the backup. >> > In this case, I think metadata could be stored in memory instead of on >> > disk, which should improve LVM snapshot performance. >> > >> > Is this theory wrong, and is this something which can be implemented >> > easily in the current LVM code ? >> > >> >> AFAIK non-persistent snapshots are already implemented see >> DM_PERSISTENT_DEV_FLAG ? I haven't look at linux kernel code how is >> it done but when I solve my lvcreate -s bug on NetBSD non-persistent >> snapshots are next :). >> >> Regards >> >> Adam. > > Yes. They are implemented in device mapper in kernel --- but no userspace > lvm tool can use them. You can only create them using dmsetup. > > Mikulas Do you have list of commands which I have to run to create persistent dm snapshot with dmsetup ? It would be handy to test my driver with dmsetup first and only after that use lvm2tools to create persistent/non-persistent snapshots. Regards Adam. -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
