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I was always hoping for more adoption of NILFS [0] - a log structured FS with continuous snapshots. In theory it should never lose data and that's a reasoning b

by hawski 8y ago

I was always hoping for more adoption of NILFS [0] - a log structured FS with continuous snapshots. In theory it should never lose data and that's a reasoning behind it not having fsck. I've seen a blog post that was debating this choice and presenting a few situations when fsck would be necessary, but I can't find it. It would be great for /home for many normal users - they could always go back. That could also be a problem when one wants to make sure that a sensitive file is really removed. It could be also used at least for some kind of archive. Possibly also for development. [0] https://en.wikipedia.org/wiki/NILFS https://en.wikipedia.org/wiki/NILFS

exikyut 8y ago
I was curious how "never lose data" works given that HDDs do not provide infinite capacity: the log is circular. This makes NILFS good for NAND flash. The continuous per-fwrite snapshotting functionality sounds awesome - I've had a few (minor but annoying) accidents with rm of late, so I'd definitely appreciate an rm-proof undelete. I was trying to figure out if NILFS had any sort of COW functionality, then realized, d'oh, of course it effectively does, via the log. To address the elephant in the room - checksumming - unfortunately NILFS doesn't (yet?) do this. The WP article links to https://www.spinics.net/lists/linux-nilfs/msg01063.html https://www.spinics.net/lists/linux-nilfs/msg01063.html, which states that the CRC32Cs that are written to disk are used only for the remount/recovery stage, and are apparently not suitable for realtime verification.
xte 8y ago
Using it on root and nearly all personal fses I second, especially hoping that it's development speed up a bit, the cleaner it's still a pain and a small wrapper to diffs between cp's can be a very nice addition!
rodgerd 8y ago
Unfortunately the mindshare it could have had was killed by Linus announcing btrfs was the future, long before it was close to ready. Almost a decade of wasted opportunity...

by hawski 8y ago

exikyut 8y ago

I was curious how "never lose data" works given that HDDs do not provide infinite capacity: the log is circular. This makes NILFS good for NAND flash. The continuous per-fwrite snapshotting functionality sounds awesome - I've had a few (minor but annoying) accidents with rm of late, so I'd definitely appreciate an rm-proof undelete. I was trying to figure out if NILFS had any sort of COW functionality, then realized, d'oh, of course it effectively does, via the log. To address the elephant in the room - checksumming - unfortunately NILFS doesn't (yet?) do this. The WP article links to https://www.spinics.net/lists/linux-nilfs/msg01063.html https://www.spinics.net/lists/linux-nilfs/msg01063.html, which states that the CRC32Cs that are written to disk are used only for the remount/recovery stage, and are apparently not suitable for realtime verification.

xte 8y ago

Using it on root and nearly all personal fses I second, especially hoping that it's development speed up a bit, the cleaner it's still a pain and a small wrapper to diffs between cp's can be a very nice addition!

rodgerd 8y ago

Unfortunately the mindshare it could have had was killed by Linus announcing btrfs was the future, long before it was close to ready. Almost a decade of wasted opportunity...