Hi, we made some benchmarks about object read/write latencies on the CERN ceph installation. The cluster has 44 nodes and ~1k disks, all on 10GE and the pool configuration has 3 copies. Client & Server is 0.67. The latencies we observe (using tiny objects ... 5 bytes) on the idle pool: write full object(sync) ~65-80ms append to object ~60-75ms set xattr object ~65-80ms lock object ~65-80ms stat object ~1ms We seem to saturate the pools writing ~ 20k objects/s (= internally 60k/s). Is there an easy explanation for 80 ms (quasi without payload) and a possible tuning to reduce that? I measured (append few bytes +fsync) on such a disk around 33ms which explains probably part of the latency. Then I tried with the async API to see if there is a difference in the measurement between wait_for_complete or wait_for_safe ... shouldn't wait_for_complete be much shorter, but I get always comparable results ... Thanks, Andreas.-- To unsubscribe from this list: send the line "unsubscribe ceph-devel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
