On Wed, Nov 16, 2016 at 12:18 PM, Burkhard Linke
<[email protected]> wrote:
> Hi,
>
>
> On 11/16/2016 11:17 AM, John Spray wrote:
>>
>> On Wed, Nov 16, 2016 at 1:16 AM, Patrick Donnelly <[email protected]>
>> wrote:
>>>
>>> On Tue, Nov 15, 2016 at 8:40 AM, Hauke Homburg <[email protected]>
>>> wrote:
>>>>
>>>> In the last weeks we enabled for testing the dir fragmentation. The
>>>> Resultat
>>>> is that we have sometimes error messages with rsync with unlink and
>>>> no-space
>>>> left on device.
>>>
>>> Enabling directory fragmentation would not cause the unlink and ENOSPC
>>> errors. Failure to unlink is caused by the stray directories on the
>>> MDS growing too large. The only current solution is to wait for the
>>> MDS to eventually purge the stray directory entries. Retry the unlink
>>> as necessary. [The other workaround is to increase
>>> mds_bal_fragment_size_max [1] which is not recommended.]
>>>
>>> Directory fragmentation is not yet considered stable so beware
>>> potential issues including data loss. However, fragmentation will
>>> allow your directories to grow to unbounded size. This includes the
>>> stray directories which would permit unlink to avoid this issue.
>>
>> The last part isn't quite right, we currently don't fragment
>> strays[1].  Unfortunately anyone who uses directory fragmentation to
>> create a super-big directory could still have issues when unlinking
>> it.  However, there are 10x stray directories and removed items are
>> spread between them, so you should be able to handle deleting a
>> directory 10x the limit on the size of a stray dir.
>
> Just out of curiosity:
>
> It is possible to increase the number of stray directories?

Nope, it's a compiled-in constant.

John

> Regards,
> Burkhard
>
> --
> Dr. rer. nat. Burkhard Linke
> Bioinformatics and Systems Biology
> Justus-Liebig-University Giessen
> 35392 Giessen, Germany
> Phone: (+49) (0)641 9935810
>
>
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