Arno Lehmann [2026-05-11 14:13:42] wrote: > Because, to get back to the original topic -- an LVM snapshot is *not* an > exact copy of the original volume, and of course much less so of the > partition, disk, or anything else. So a block level dump of an LVM snapshot > is not something you can just dump back as a disaster recovery step.
Interesting. Could you clarify what you mean here? I've used LVM snapshots in the past then `ddrescue`d the data back&forth to a target LVM volume and that seemed to work well (and I assumed it's supposed to work well). So in which cases is it expected to fail? > And. of course, it doesn't let gaps between block storage consistency, file > system consistency, file system "cleanness", file contents consistency and > application data consistency vanish. IME it does provide "filesystem consistency". Definitely not "filesystem cleanness", indeed. Not sure what you mean by "file contents consistency" (are you referring to things like ext3's "data=writeback")? As for "application data consistency", yes, that's a more complicated question. [ Just last week-end my desktop's power supply died while in the middle of a big set of `git pull` operations. Of course, after I replaced the power supply, the filesystem was perfectly "consistent" yet many of the new files ended up empty, including some in the `.git/objects` directory, leading to errors about missing blobs and whatnot. Not sure if that was a bug in Git or a misfeature of ext4's default journaling. ] === Stefan
