[dm-devel] hunt for 2.6.37 dm-crypt+ext4 corruption? (was: Re: dm-crypt barrier support is effective)

[Jon Nelson]

On Thu, Dec 9, 2010 at 12:01 PM, Ted Ts'o <tytso at mit.edu> wrote:
> On Tue, Dec 07, 2010 at 09:37:20PM -0600, Jon Nelson wrote:
>> One difference is the location of the transaction logs (pg_xlog). In
>> my case, /var/lib/pgsql/data *is* mountpoint for the test volume
>> (actually, it's a symlink to the mount point). In your case, that is
>> not so. Perhaps that makes a difference?  pgsql_tmp might also be on
>> two different volumes in your case (I can't be sure).
>
> I just tried tried to run t.sql five times with /var/lib/postgres as a
> mountpoint for a 5400 rpm disk, and I still haven't been able to
> replicate it.

You should be OK, there. Are you using encryption or no?
I had difficulty replicating the issue without encryption.

> If you can point out how to query pgsql_tmp (I'm using a completely
> default postgres install), that would be helpful, but I don't think it
> would be going anywhere else.

Normally it's /var/lib/pgsql/data/pgsql_tmp (or
/var/lib/postgres/data/pgsql_tmp in your case). By placing
/var/lib/{postgresql,pgsql}/data on the LUKS + ext4 volume, on both
openSUSE 11.3 and Kubuntu, I was able to replicate the problem easily,
in VirtualBox. I can give qemu a try. In both cases I was using a
2.6.37x kernel.

-- 
Jon