Re: linux software RAID, 2.6.6, XFS, Postgres: corrupt files

["Thomas J. Teixeira" <tjt@xxxxxxxxxxxxxx>]

Resending this since it didn't seem to go through the first time -- I'm
looking for kernel diagnostic tools.

- Tom

-- RESEND STARTS HERE --

I'm working with Ian Westmacott on this corruption problem and was
wondering if there are any tools for examining the state of kernel XFS
buffers of a running system. I didn't see anything obvious in the source
RPM for xfsprogs from SuSE 9.1, but I was looking for something that
would open something like /dev/kmem (I'm a reformed unix kernel hacker,
but don't have experience with linux at this level).

The reasoning is that although we haven't been able to construct a
reproducible test case in our lab, we can go to a beta site and stop our
application and postgres at which point there should be no open files on
the XFS file system which is used exclusively by postgres. From the
symptoms we are seeing -- no corruption as long as the file system stays
mounted -- I would expect to find some data buffer in a strange state --
something like dirty but locked in a way that prevents it from being
written, but keeps it around so reads will find the data. If XFS were
simply dropping a dirty bit, I would expect to see corruption even while
the file system stays continuously mounted.

Thanks in advance,

- Tom Teixeira