[Lustre-discuss] Disappearing OSTs

[Bernd Schubert]

On Fri, May 02, 2008 at 07:34:25PM -0700, Andreas Dilger wrote:
> On May 01, 2008  11:52 -0400, jrs wrote:
> 
> Note that anything over 2TB (I think, maybe 4TB?) needs a GPT partition table,
> or the size of the device is incorrect.
> 

And I have a warning for people who need to use GPT tables - from our 
experience the kernel silently ignores GPT. We run into this already
some months ago. Everything seemed to be correct, /proc/partitions
was what we did expect, but then we noticed very odd data corruption.
First we thought we introduced a bug into ldiskfs (you know, we
usually need more recent kernels than you support), but after
adding a patch printing the partition offsets, we recognized it 
simply did use a dos partition table and wrapped around at 4TiB.

Oh well, I wanted to to further investigate this already for a long
time. But since it can be easily worked around by specifying the 
"gpt" kernel command line parameter other issues always did have
higher priority.

Bernd

PS: This gpt bug is in 2.6.20 and 2.6.22, don't know if it fixed in more 
recent kernel versions.