[Lustre-discuss] Disappearing OSTs

[Thomas Roth]

Hello Bernd,

could you give some details on the data corruption you have seen?
We have been using GPT tables for some time now, but the partitions have 
been filled up only on NFS servers, not on Lustre OSS. And on these NFS 
volumes there were no problems attributed to the partition size.

This would also depend on the actual size limit: I understand GPT tables 
are necessary for partitions > 2TB. The largest partition I have set up 
so far was 3.2 TB, so if you are sure about your number of 4 TiB, we 
might simply be on the lucky side.

And the workaround is specifying "gpt" on the kernel command line ? For 
once an easy solution ;-)

Regards,
Thomas



Bernd Schubert wrote:
> 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.
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