Hi Tuomos, Can you paste the command you ran to do the test? Thanks, Mark On 06/30/2015 12:18 PM, Tuomas Juntunen wrote:
Hi It’s not probably hitting the disks, but that really doesn’t matter. The point is we have very responsive VM’s while writing and that is what the users will see. The iops we get with sequential read is good, but the random read is way too low. Is using SSD’s as OSD’s the only way to get it up? or is there some tunable which would enhance it? I would assume Linux caches reads in memory and serves them from there, but atleast now we don’t see it. Br, Tuomas *From:*Somnath Roy [mailto:Somnath.Roy@xxxxxxxxxxx] *Sent:* 30. kesäkuuta 2015 19:24 *To:* Tuomas Juntunen; 'ceph-users' *Subject:* RE: Very low 4k randread performance ~1000iops Break it down, try fio-rbd to see what is the performance you getting.. But, I am really surprised you are getting > 100k iops for write, did you check it is hitting the disks ? Thanks & Regards Somnath *From:*ceph-users [mailto:ceph-users-bounces@xxxxxxxxxxxxxx] *On Behalf Of *Tuomas Juntunen *Sent:* Tuesday, June 30, 2015 8:33 AM *To:* 'ceph-users' *Subject:* Very low 4k randread performance ~1000iops Hi I have been trying to figure out why our 4k random reads in VM’s are so bad. I am using fio to test this. Write : 170k iops Random write : 109k iops Read : 64k iops Random read : 1k iops Our setup is: 3 nodes with 36 OSDs, 18 SSD’s one SSD for two OSD’s, each node has 64gb mem & 2x6core cpu’s 4 monitors running on other servers 40gbit infiniband with IPoIB Openstack : Qemu-kvm for virtuals Any help would be appreciated Thank you in advance. Br, Tuomas ------------------------------------------------------------------------ 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). _______________________________________________ ceph-users mailing list ceph-users@xxxxxxxxxxxxxx http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
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