Re: Linux filesystems was [Re: Debian cd supporting ext4.]
On Tue, 27 Jul 2010, Stan Hoeppner <stan@hardwarefreak.com> writes:
> What write operations were you performing at the time you pulled the plug?
> Unless you were writing the superblock it'd be almost impossible to hose the
> filesystem to the point it couldn't mount. Were you doing a resize operation
> when you pulled the plug? xfs_growfs? As far as recovery, it's automatic
> upon mounting the XFS filesystem. What do you mean, precisely, by "couldn't
> *recover* the / fs"?
Vanilla XFS with noatime,notail like basic mount options. The test was
simple, I was just typing "SELECT 1" from a psql command line (this
query shouldn't even hit to disk, it just basically returns 1) and
unplugged machine. At boot, I dropped to fsck command line. At command
prompt, I manually fiddled around with fsck of xfs to recover the
unmounted / filesystem, but had no luck. (I also tried recommendations
and informative messages supplied by manpages and command
outputs/warnings.) Also if you would Google, it shouldn't be hard to
spot similar experiences from other people.
At NASA, they might have genius technicians; but, IMHO a majority of the
linux users would want a filesystem to recover without a prompt from the
user.
> I'm basically a one man army trying to defeat misinformation WRT XFS
> and attempt to educate ppl with the correct information.
I am glad -users ml have you; and I'd be really, really appreaciated if
somebody having experience and knowledge on fs issues can shed some
light to our ignorance. I also support the replacement of default fs
with something that is much more recent. From this point of view, XFS is
a superior alternative. You are totally right with your claims about its
advantages over other alternatives. But as you can see, people still
complain about XFS's sensitivity to power failures. Assuming a majority
of your users aren't behind a UPS, you can sell/ship your product with
such a default filesystem choice. But as you said, there are no
published concrete benchmarks about this issue. It is all what people
claim in the mailing lists. If you would share some of your findings
about "Power Failures and XFS" to convince us, I'm sure most of us will
be happy to advocate XFS's this achievement.
Regards.
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