Hi,
On 11/16/2016 11:17 AM, John Spray wrote:
On Wed, Nov 16, 2016 at 1:16 AM, Patrick Donnelly <pdonnell@xxxxxxxxxx> wrote:
On Tue, Nov 15, 2016 at 8:40 AM, Hauke Homburg <hhomburg@xxxxxxxxxxxxxx> 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?
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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