Unprivileged filesystem mounts, 2018 edition

Posted May 30, 2018 22:30 UTC (Wed) by Paf (subscriber, #91811)
In reply to: Unprivileged filesystem mounts, 2018 edition by rahvin
Parent article: Unprivileged filesystem mounts, 2018 edition

That’s really a pretty big question, but as someone who works on a file system and follows related news, here’s my sense of the zeitgeist.

I can think of three broad types worth addressing.

For traditional extent based file systems on Linux, EXT4 and XFS are clearly best of breed. There is an emerging consensus among enterprise distributions in favor of XFS as the default, if that helps, but neither is dramatically superior in general.

I can’t speak to log structured except to say that those are mostly built in to flash devices rather than used directly.

For copy-on-write, there are three real choices. ZFS, almost certainly best of breed but with complex legal issues, BTRFS, which you can get various answers on the readiness of, and bcachefs which is compelling but pretty clearly still too new.

Unprivileged filesystem mounts, 2018 edition

Posted May 30, 2018 23:39 UTC (Wed) by rahvin (guest, #16953) [Link] (4 responses)

How would you rate JFS in comparison?

Unprivileged filesystem mounts, 2018 edition

Posted May 31, 2018 11:51 UTC (Thu) by bendystraw (guest, #124653) [Link]

JFS is great; it's without a doubt my favorite file system for my OS/2 cluster.

Unprivileged filesystem mounts, 2018 edition

Posted Jun 2, 2018 10:27 UTC (Sat) by stevan (guest, #4342) [Link] (2 responses)

Personal experience - JFS remains the only filesystem from which I have never lost data, though I have not used BTRFS or ZFS in anger. It's old and relatively unloved, but seems to work at human-manageable-scale systems. Data loss leaves lasting scars.

Unprivileged filesystem mounts, 2018 edition

Posted Jun 20, 2018 18:56 UTC (Wed) by mstone_ (subscriber, #66309) [Link] (1 responses)

I've lost data to JFS. I'm also not really sure why it exists other than as a me-too from IBM as it offered nothing that wasn't available in other linux filesystems.

Unprivileged filesystem mounts, 2018 edition

Posted Jun 21, 2018 21:33 UTC (Thu) by philipstorry (subscriber, #45926) [Link]

I'd imagine that IBM offered it so that their customers could migrate to Linux.

It's curious to hear you call JFS a "me-too", as it predates the Linux kernel by over a year. (It originated with IBM's AIX systems in 1990, was later ported to OS/2, and finally to Linux.)

It's actually quite a nice filesystem for general use. It's got metadata journalling, uses extents and allocation groups, and has a reputation for being fast even under heavy loads whilst not consuming much CPU or memory itself.

XFS is probably the filesystem it's most natural to compare JFS to, as they have similar core features and were both ported to Linux at around the same time in 2001. It's also an OS that came from an old UNIX (IRIX) and is only three years younger than JFS, so understandably has a number of similar design decisions. It seems both were pretty cutting edge for the early 1990's!

I wasn't terribly involved with Linux back in 2001 when they were both ported, but it seems that XFS rapidly won the mindshare battle - it accrued more developers around it. Perhaps that's because SGI were more open to contributions from other developers than IBM were? Or maybe it's because its 64-bit on-disk structure gave it higher headline stats in terms of maximum sizes?

Certainly one of the things I've recently admired about JFS is that it's very much in "maintenance mode" these days. That may not be exciting or sexy, but it does make it attractive it you're looking for reliability. I suspect that the unchanging nature of JFS is why it tends to get discounted - it's not adding new features, but the ones it has are well implemented and reliable. But the tech industry and community likes the shiny new things, and JFS lost its shiny new feel over a decade ago.

Now it's simply a reliable workhorse.

The main reasons to avoid it are either feature requirements (and they're more likely to be COW based) or simply the concern that at some point it may be deprecated due to its inactivity. That sort of concern is kind of a self-reinforcing feedback look really, and I suspect it's started to happen already.

However, it's served three different operating systems well, and is still a viable choice for many purposes. It's a pity JFS doesn't get a little more respect...