[xfs-masters] [Bug 51321] Huge data loss on power outage

[bugzilla-daemon at bugzilla.kernel.org]

https://bugzilla.kernel.org/show_bug.cgi?id=51321


Malcolm Haak <malcolm at sgi.com> changed:

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                 CC|                            |malcolm at sgi.com




--- Comment #1 from Malcolm Haak <malcolm at sgi.com>  2012-12-12 23:10:03 ---
Hi Guys,

I have seen this behaviour also. I first noticed it late in the 3.5.X builds
(Currently I am running 3.7.0-rc8). It has been exacerbated by the addition of
more RAM in my system. I now have 16GB vs the 8GB I had previously, the ram
upgrade was to alleviate heavy swapping due to the workload on my machine.

In my case xfsrepair wa s failing claiming that the Journal is corrupted.
Running it with a -l to ignore journal gets me a working filesystem, but it has
heavy corruption in many files, even files with only minor changes (in the
order of only a few bytes). In a HA situation this could be catastrophic.

It feels like journal entries are ending up in buffer cache and not getting
written out in a reasonable time frame. I say this because now that there is
extra ram free to be used as buffer cache the issue is much worse, previously
when I was running less ram and frequently ending up with some more than
moderate swap usage, I did not see this issue with the same frequency. The
improper shutdowns in my case are caused by a buggy 3G dongle driver not
behaving with suspend correctly.


If you need me to do testing I have a bunch of VM's I can use to look for the
exact 'triggers' but it seems any files changed since the last sync will get
damaged.

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