A Short History of Btrfs 241
diegocgteleline.es writes "Valerie Aurora, a Linux file system developer and ex-ZFS designer, has posted an article with great insight on how Btrfs, the file system that will replace Ext4, was created and how it works. Quoting: 'When it comes to file systems, it's hard to tell truth from rumor from vile slander: the code is so complex, the personalities are so exaggerated, and the users are so angry when they lose their data. You can't even settle things with a battle of the benchmarks: file system workloads vary so wildly that you can make a plausible argument for why any benchmark is either totally irrelevant or crucially important. ... we'll take a behind-the-scenes look at the design and development of Btrfs on many levels — technical, political, personal — and trace it from its origins at a workshop to its current position as Linus's root file system.'"
Re:So, (Score:5, Interesting)
Aside from Copy on Write, one other feature that this filesystem has that I would consider essential in a modern filesystem is full checksumming. As drives get larger and larger, the chance of a random undetected error on write increases and having full checksums on every block of data that gets written to the drive means that when something is written, I know it's written. It also means that when I read something back from the disk, I know that it was the data that was put there and didn't get silently corrupted by the [sata controller | dodgy cable | cosmic rays] on the way to the disk and back.
So, what is the status of btrfs? (Score:5, Interesting)
Is it Beta? The fact that Linus runs it as his root fs doesn't tell me much. Now, if you told me that's what he uses for ~/, I would be more impressed.
The important question to me is, how long 'til it gets in the major distributions?
Re:Linus', not Linus's. (Score:3, Interesting)
There doesn't seem to be any hard and fast rules about anything in British english! ;-)
In Fowler's Modern English Usage, which is generally considered to be the bible of english usage by UK journalists and writers, there's an article called "Possessive Puzzles". In that, he says it was "formerly customary" to drop the last 's', but not any more.
If it was formerly customary in Fowler's day, i reckon it must be well and truly archaic now.
Re:So, what is the status of btrfs? (Score:5, Interesting)
Re:So, what is the status of btrfs? (Score:1, Interesting)
Yeah, but those operating systems suck in other ways, so no thanks. I'll get by with ext3/4 and xfs until btrfs is production ready. YMMV.
Re:So, (Score:3, Interesting)
Re:So, what is the status of btrfs? (Score:3, Interesting)
Yeah, right.
I want to see you back out a series of patches on Linux and revert to the previous configuration because the updates broke something.
# echo =package-cat/package-offending-version >> /etc/portage/package.mask
# emerge -C =package-cat/package-offending-version && emerge package-cat/package
Rinse and repeat for any other packages which may be borked.
Re:Yet another "modern" FS without undelete... (Score:3, Interesting)
I undelete stuff all the time on Linux. you just open the trash and pull the stuff out. Once you empty the trash it is gone though. If you're using a command-line and 'rm' stuff though, that's entirely your fault for using such a low-level power-user interface for file management.
There are serious performance consequences and fragmentation consequences of supporting undelete at the filesystem level. But supporting snapshots is something high performance filesystems do, and snapshots are way more useful than undelete. Especially if snapshots are cheap enough to make them automated. Imagine having 24 revisions of your filesystem of the last 24 hours. This is done all the time on real Filers. I love it when my home directories at work are snapshot this way, makes it super easy to recover screwed up source code due to my inability to check in source before I make huge changes to it.
I think we should demand that Linux get snapshot support that is generally available (like default on RHEL,SuSE,Ubuntu,etc.) It's a feature that has been missing from Linux. While things like FreeBSD have had it standard for many years now.
Re:Oh great (Score:5, Interesting)
I'd rephrase that. It eliminates the common cases where you'd need fsck on a conventional filesystem.
ZFS' design makes consistency failure extremely unlikely. I understand why they claim it doesn't need fsck ("always consistent on disk"). [sun.com] There is controversy over whether there should be a scavenging tool. [opensolaris.org] Some people want one for peace of mind.
But again, most cases of ZFS pool loss where some believe a scavenger may have saved them, may actually have been solved by more aggressive rollback (I believe work is being done on this).
Anyone interested in this issue should follow the ZFS mailing list. [opensolaris.org]
Re:Duh... (Score:3, Interesting)
Perhaps because they are writing software which is by FAR most useful when it is used as far and wide as possible, while using a license which makes that goal extremely difficult to achieve, unnecessarily.
Honestly, the only reason anyone cares about Btrfs is because the license on ZFS is too restrictive for inclusion in Linux, and NOBODY has opted to write their own implementation under a GPL or other, freer, license.