Hi All, I am seeing an issue with ceph performance. Starting from an empty cluster of 5 nodes, ~600Tb of storage.
monitoring disk usage in nmon I see rolling 100% usage of a disk.
Ceph -w doesn’t report any spikes in throughput and the application putting
data is not spiking in the load generated.
│sdg2 0% 0.0 537.5| > |
│
│sdh 2% 4.0 4439.8|RW >
│
│sdh1 2% 4.0 3972.3|RW >
│
│sdh2 0% 0.0 467.6| > |
│
│sdj 3% 2.0 3524.7|RW >
│
│sdj1 3% 2.0 3488.7|RW >
│
│sdj2 0% 0.0 36.0| > |
│
│sdk 99% 1144.9 3564.6|RRRRRRRRRRRRRWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWW>
│
│sdk1 99% 1144.9 3254.9|RRRRRRRRRRRRRWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWW>
│
│sdk2 0% 0.0 309.7|W > |
│
│sdl 1% 4.0 955.1|R > |
│
│sdl1 1% 4.0 791.3|R > |
│
│sdl2 0% 0.0 163.8| > |
Is this anything to do with the way objects are stored on the file system?
I remember reading that as the number of objects grow the files on disk are
re-orginised?
This issue for obvious reasons causes a large degradation in performance, is
there a way of mitigating it?
Will this go away as my cluster reaches a higher level of disk utilisation?
Kind Regards,
Bryn Mathias
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