Luca Berra schrieb:
On Fri, Jun 02, 2006 at 01:08:24PM +0200, Kevin Eilers wrote:
Do the maintainers of the raid subsystem already know about this?
i don't think so,
could you or someone make a recap and cc:
linux-raid@xxxxxxxxxxxxxxx
L.
Did that. Here's what I have sent there:
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Hi List,
just to draw your attention to some discussion starting out here:
http://thread.gmane.org/gmane.linux.kernel.device-mapper.dm-crypt/1576/focus=1576
and going on here:
http://thread.gmane.org/gmane.linux.kernel.device-mapper.dm-crypt/1617/focus=1617
To recap, what has been found so far is:
1. There are problems with the combination of RAID and device mapper
(e.g. for encrypted filesystems). The thread started off with this
observation.
2. There are filesystem corruptions with heavy loads (i.e. copying big
files or many files to the filesystem). The bug usually takes long to
reproduce.
3. Problems occur with any filesystem type (ext3, reiser4 et. al.).
4. Problems occur with RAID-5 and RAID-6. Both are O.K. without dm-crypt.
5. Problems are unaffected by different ciphers under dm-crypt (at least
AES, Serpent and Twofish expose the bug). dm-linear is reported to have
failed, too. So, we suspect that neither dm-crypt nor ciphers are the
culprit here, but rather the device mapper core functionality or RAID
subsystem.
6. Bug seems to exist in at least kernel 2.6.13 to 2.6.16 (2.6.17 not
yet tested, earlier versions may be affected).
There have been discussions going on about his from earlier kernel
versions, like here:
http://lwn.net/Articles/150583/
Neil's suggestion indicates that there may be a race condition stacking
md and dm over each other, but I have not yet tested that patch. I once
had problems stacking cryptoloop over RAID-6, so it might really be a
stacking problem. We don't know yet if LVM over RAID is affected as well.
This bug is very critical and should be fixed as soon as possible, IMHO.
Uwe
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