|
My understanding is that when using direct=1 on a raw block device FIO (aka-you) will have to handle all the sector alignment or the request will get buffered to perform the alignment.
Try adding the –blockalign=512b option to your jobs, or better yet just use the native FIO RBD engine. Something like this (untested) -
[A] ioengine=rbd clientname=admin pool=rbd rbdname=fio_test direct=1 group_reporting=1 unified_rw_reporting=1 time_based=1 rw=read bs=4MB numjobs=16 ramp_time=10 runtime=20 From:
ceph-users <ceph-users-bounces@xxxxxxxxxxxxxx> on behalf of V Plus <v.plussharp@xxxxxxxxx> 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... |
_______________________________________________ ceph-users mailing list ceph-users@xxxxxxxxxxxxxx http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
