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Fill up the image with big write (say 1M) first before reading and you should see sane throughput. Thanks & Regards Somnath From: ceph-users [mailto:ceph-users-bounces@xxxxxxxxxxxxxx]
On Behalf Of V Plus Hi Guys, we have a ceph cluster with 6 machines (6 OSD per host). 1. I created 2 images in Ceph, and map them to another host A (outside the Ceph cluster). On host A, I got /dev/rbd0 and /dev/rbd1. 2. I start two fio job to perform READ test on rbd0 and rbd1. (fio job descriptions can be found below) "sudo fio fioA.job -output a.txt & sudo fio fioB.job -output b.txt & wait" 3. After the test, in a.txt, we got bw=1162.7MB/s, in b.txt, we get bw=3579.6MB/s. The results do NOT make sense because there is only one NIC on host A, and its limit is 10 Gbps (1.25GB/s). I suspect it is because of the cache setting. But I am sure that in file /etc/ceph/ceph.conf on host A,I already added: [client] rbd cache = false Could anyone give me a hint what is missing? why.... Thank you very much. fioA.job: [A] direct=1 group_reporting=1 unified_rw_reporting=1 size=100% time_based=1 filename=/dev/rbd0 rw=read bs=4MB numjobs=16 ramp_time=10 runtime=20 fioB.job: [B] direct=1 group_reporting=1 unified_rw_reporting=1 size=100% time_based=1 filename=/dev/rbd1 rw=read bs=4MB numjobs=16 ramp_time=10 runtime=20 Thanks... |
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