On Mon, May 11, 2026 at 06:21:43PM +0200, Arno Lehmann wrote: > Hi Stefan, all,
[...] > I think more like the infamous XFS behaviour :-) > But actually a slightly different thing -- when a program has a file open, > you can read or snapshot it at any arbitrary time, and afaik there's no way > to ensure that all buffers are flushed at the time the snapshot takes place. > The lvm-filesystem-integration tries to work into that direction, but I > believe it would be hard to guarantee that. Essentially, the same problem > you often find recommendations to run sync twice for -- you reduce the > window for trouble as much as possible, but short of enforcing a read-only > remount or unmount, there will always be a slight risk left. That second part I understand. Whatever the application keeps on cache and lazyly writes out ca be anybody's guess. Some applications go to lengths in keeping consistency and timeliness of disk images (notably RDBMSes, but also, e.g. civilised editors), some not so much. Silently pulling a snapshot "from behind" seems to be near the worst case for that. Cheers -- t
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