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] 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 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
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