Ts'o: Delayed allocation and the zero-length file problem [LWN.net]

Ts'o: Delayed allocation and the zero-length file problem

Posted Mar 14, 2009 9:15 UTC (Sat) by petegn (guest, #847)
Parent article: Ts'o: Delayed allocation and the zero-length file problem

It's all very well people ranting on about Posix allows this that and other ect but the fact of the matter is yet again the Linux community is having ALPHA quality pushed on it as distro ready . The very best thing would be for people to STOP using EXT4 completely and if their distro tries to force EXT4 then simply change distro there are enough out there to choose from .

Me personally i gave up on the entire EXT* filesystem some years ago and will NEVER go back you can slag Reiserfs off all you want but it beats the living crap outta EXT*

I use Reiserfs for the small boot partition then XFS and it just behaves correctly ALL the time .

This may be slightly off topic but this my experence with EXT systems total unreliabity

YMMV mine is VERY fixed

(Log in to post comments)

Finny that - you must be pretty unique

Posted Mar 14, 2009 11:26 UTC (Sat) by khim (subscriber, #9252) [Link]

I use Reiserfs for the small boot partition then XFS and it just behaves correctly ALL the time.

Actully XFS is much worse in case of crush than any EXT* filesystem and it often used as "you can do this because XFS is doing this". Sorry, but I just don't buy you story. How often you XFS-based system crashes? How consistent it's afterwards? We need to know before your evidence can be used in this dicussion...

My personal experience with XFS was horrible exactly with behavior like descibed: save the file or configuration on disk, power off the system - then reboot and find out that file has zero bytes now. Few such incidents were enough for me. If you answer is "don't do this" then how the hell your experience is relevant to topic?

Finny that - you must be pretty unique

Posted Mar 14, 2009 22:56 UTC (Sat) by ikm (subscriber, #493) [Link]

Seconded -- over time, I've lost numerous hours of my work because of XFS (which I happened to have on some machines out of the popular belief that it's cool) due to poor crash recovery, and I've never lost *any* bit of information on ext2/3.

Finny that - you must be pretty unique

Posted Mar 15, 2009 3:32 UTC (Sun) by dgc (subscriber, #6611) [Link]

> If you answer is "don't do this" then how the hell your
> experience is relevant to topic?

XFSQA tests 136-140, 178 and a couple of others "do this"
explicitly and have done so for a couple of years now. This failure
scenario is tested every single time XFSQA is run by a developer.
Run those tests on 2.6.21 and they will fail. Run them on 2.6.22
and they will pass...

FWIW, XFS is alone in the fact that it has:

a) a publicly available automated regression test suite;

(http://git.kernel.org/?p=fs/xfs/xfstests-dev.git;a=summary)

b) a test suite that is run all the time by developers;

c) ioctls and built-in framework to simulate the effect of
power-off crashes that the QA tests use.

This doesn't mean XFS is perfect, but it does mean that it is known
immediately when a regression appears and where we need improvements
to be made.

IOWs, we can *prove* that the (once) commonly seen problems in XFS
have been fixed and will remain fixed. It would be nice if people
recognised this rather relevant fact instead of flaming
indiscriminately about stuff that has been fixed....

Finny that - you must be pretty unique

Posted Mar 15, 2009 13:15 UTC (Sun) by hmh (subscriber, #3838) [Link]

Some of us do know the XFS guys are doing an excellent job tracking down regressions and bugs :-)

The only thing I never use XFS for is the root filesystem, and that's because nobody has seen fit to fix the XFS fsck to detect it is being run on a read-only filesystem, and to switch to xfs_repair on-the-fly.

It is no fun to need boot CDs to make sure everything is kosher in the root filesystem (or worse, to repair it)...

But it really works well for the MTA queues and squid spool, for example.

Ts'o: Delayed allocation and the zero-length file problem

Posted Mar 15, 2009 4:02 UTC (Sun) by bojan (subscriber, #14302) [Link]

> It's all very well people ranting on about Posix allows this that and other ect but the fact of the matter is yet again the Linux community is having ALPHA quality pushed on it as distro ready.

POSIX is a standard that Linux kernel is attempting to implement. Explaining to people what it says is not ranting.

Just remember, when Firefox developers got blasted for the performance hit in in FF 3.0, it wasn't their fault. It was the fsync problem in ext3, which is still there.

Similarly this time, Ted is getting blasted for other people's bugs, partially caused by completely unusable fsync on ext3.

Finally, if you don't like using new software, then don't use it. Nobody is twisting your arm.