Messages in this thread | | | Date | Thu, 18 Jul 2002 10:50:34 -0400 (EDT) | From | Bill Davidsen <> | Subject | Re: [ANNOUNCE] Ext3 vs Reiserfs benchmarks |
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On Tue, 16 Jul 2002, Andreas Dilger wrote:
> This is all done already for both LVM and EVMS snapshots. The filesystem > (ext3, reiserfs, XFS, JFS) flushes the outstanding operations and is > frozen, the snapshot is created, and the filesystem becomes active again. > It takes a second or less. Then dump will guarantee 100% correct backups > of the snapshot filesystem. You would have to do a backup on the snapshot > to guarantee 100% correctness even with tar.
I think I'm missing a part of this, the "a snapshot is created" sounds a lot like "here a miracle occurs." Where is this snapshot saved? And how do you take it in one sec regardless of f/s size? Is this one of those theoretical things which requires two mirrored copies of the f/s so you will still have RAID-1 after you break one? Or are changes journaled somewhere until the snapshot is transferred to external media? And how do you force applications to stop with their files in a valid state?
-- bill davidsen <davidsen@tmr.com> CTO, TMR Associates, Inc Doing interesting things with little computers since 1979.
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