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:[email protected]] On Behalf Of V Plus Sent: Sunday, December 11, 2016 5:44 PM To: [email protected] Subject: [ceph-users] Ceph performance is too good (impossible..)... 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... PLEASE NOTE: The information contained in this electronic mail message is intended only for the use of the designated recipient(s) named above. If the reader of this message is not the intended recipient, you are hereby notified that you have received this message in error and that any review, dissemination, distribution, or copying of this message is strictly prohibited. If you have received this communication in error, please notify the sender by telephone or e-mail (as shown above) immediately and destroy any and all copies of this message in your possession (whether hard copies or electronically stored copies).
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