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Hello Ceph Users, I am finding that the write latency across my ceph clusters isn't great and I wanted to see what other people are getting for op_w_latency. Generally I am getting 70-110ms latency. I am using: ceph --admin-daemon /var/run/ceph/ceph-osd.102.asok perf dump | grep -A3 '\"op_w_latency' | grep 'avgtime' Better like this: ceph daemon osd.102 perf dump | jq '.osd.op_w_latency.avgtime'
What is your hardware? Your CPU, RAM, Eth?Ram, CPU and network don't seem to be the bottleneck. The drives are behind a dell H810p raid card with a 1GB writeback cache and battery. I have tried with LSI JBOD cards and haven't found it faster ( as you would expect with write cache ). The disks through iostat -xyz 1 show 10-30% usage with general service + write latency around 3-4ms. Queue depth is normally less than one. RocksDB write latency is around 0.6ms, read 1-2ms. Usage is RBD backend for Cloudstack.
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