[Lustre-discuss] Question about No space left on device

[Chad Kerner]

Brian, yes, the users are not specifying any stripe parameters, and they 
are getting this error.


Chad

On Thu, 22 Jan 2009, Brian J. Murrell wrote:

> On Thu, 2009-01-22 at 12:11 -0600, Chad Kerner wrote:
>> Hello,
>>
>>       We are running lustre 1.6.6 and are seeing a weird error on space
>> usage.  The filesystem is not anywhere near full, but writes are failing
>> if they hit OST 23.
>>
>> if I do an lfs setstripe -i 23 chad, and then do
>> # dd if=/dev/zero of=chad
>> dd: writing to `chad': No space left on device
>> 26+0 records in
>> 25+0 records out
>> #
>>
>> The actual device is fairly full.
>> # df /lustre/home/ost_h_24
>> Filesystem           1K-blocks      Used Available Use% Mounted on
>> /dev/mapper/ost_h_24 564172088 509452368  26061444  96%
>> /lustre/home/ost_h_24
>
> At 4% free, unless you have changed the "reserved space" on the OSTs'
> filesystem (see the ops manual) you are into the space that a normal
> user is not allowed to write (and gets ENOSPC when he does).  By default
> 5% of every device is reserved for root.
>
> That said, you really are running that OST quite full.  Historically
> (I'm not sure if this still applies -- maybe one of our ext3 experts can
> comment) if you run an ext3 filesystem >80% you start to get performance
> degradations.
>
> Are you getting any ENOSPC (-28) errors other than by trying to force a
> write to that full OST?  I ask because unless directed specifically to
> use a particular OST (as your example does) the MDS should avoid using a
> full OST.  If it's not, that's a bug.
>
> b.
>
>