What about other filesystems?

Posted Jan 15, 2021 20:19 UTC (Fri) by joib (subscriber, #8541)
In reply to: What about other filesystems? by Wol
Parent article: Fast commits for ext4

Carefully ordering writes was the idea behind <a href="https://www.usenix.org/legacy/publications/library/procee...">soft updates</a> previously(?) used in the BSD FFS. I believe it was replaced by a more traditional journaling approach because modern hardware is dependent on queuing for good performance, and all current hardware command queuing mechanisms are unordered. On such hardware soft updates wasn't able to keep up with journaling, which is better able to batch updates.

What about other filesystems?

Posted Jan 16, 2021 0:13 UTC (Sat) by wahern (subscriber, #37304) [Link] (1 responses)

You may be thinking of NetBSD, which replaced softupdates with journaling in FFS. Softupdates is still the only option on OpenBSD, but I'm more than contented on that front. AFAIU, FreeBSD also still supports softupdates, though the FreeBSD community seems to be migrating to ZFS.

What about other filesystems?

Posted Feb 1, 2021 14:25 UTC (Mon) by drjohnnyfever (guest, #144560) [Link]

The situation on FreeBSD is actually a bit complicated. The current default configuration uses journaled soft updates (su+j) which work like traditional soft updates with the exception that there is enough metadata journaled to avoid having to run a background fsck to reclaim space from orphaned allocations.

FreeBSD also supports proper journaling (logging) with gjournal which works at the block layer rather than in UFS itself. If I recall correctly, gjournal keeps a proper intent log of disk writes rather than just a metadata journal. It also allows you to use a separate device for the log.

ZFS does seem to be the way forward on FreeBSD but Netflix is pretty big consumer of UFS/FFS so they have been sponsoring continued development.