Hi Nick,
I dont have separate SSD / HDD for journal. I am using a 10 G partition on the same HDD for journaling. They are rotating HDD's and not SSD's.
I am using below command to run the test:
fio --name=test --filename=test --bs=4k --size=4G --readwrite=read / write
I did few kernel tuning and that has improved my write IOPS. For read I am using rbd_readahead and also used read_ahead_kb kernel tuning parameter.
Also I should mention that its not x86, its on armv7 32bit.
Thanks.
Daleep Singh Bais
On Wed, Sep 9, 2015 at 1:55 PM, Nick Fisk <nick@xxxxxxxxxx> wrote:
> -----Original Message-----
> From: ceph-users [mailto:ceph-users-bounces@xxxxxxxxxxxxxx] On Behalf Of
> Daleep Bais
> Sent: 09 September 2015 09:18
> To: Ceph-User <ceph-users@xxxxxxxx>
> Subject: Poor IOPS performance with Ceph
>
> Hi,
>
> I have made a test ceph cluster of 6 OSD's and 03 MON. I am testing the read
> write performance for the test cluster and the read IOPS is poor.
> When I individually test it for each HDD, I get good performance, whereas,
> when I test it for ceph cluster, it is poor.
Can you give any further details about your cluster. Are your HDD's backed by SSD journals?
>
> Between nodes, using iperf, I get good bandwidth.
>
> My cluster info :
>
> root@ceph-node3:~# ceph --version
> ceph version 9.0.2-752-g64d37b7
> (64d37b70a687eb63edf69a91196bb124651da210)
> root@ceph-node3:~# ceph -s
> cluster 9654468b-5c78-44b9-9711-4a7c4455c480
> health HEALTH_OK
> monmap e9: 3 mons at {ceph-node10=192.168.1.210:6789/0,ceph-
> node17=192.168.1.217:6789/0,ceph-node3=192.168.1.203:6789/0}
> election epoch 442, quorum 0,1,2 ceph-node3,ceph-node10,ceph-
> node17
> osdmap e1850: 6 osds: 6 up, 6 in
> pgmap v17400: 256 pgs, 2 pools, 9274 MB data, 2330 objects
> 9624 MB used, 5384 GB / 5394 GB avail
> 256 active+clean
>
>
> I have mapped an RBD block device to client machine (Ubuntu 14) and from
> there, when I run tests using FIO, i get good write IOPS, however, read is
> poor comparatively.
>
> Write IOPS : 44618 approx
>
> Read IOPS : 7356 approx
1st thing that strikes me is that your numbers are too good, unless these are actually SSD's and not spinning HDD's? I would expect to get around a max of 600 read IOPs for 6x 7.2k disks, so I guess either you are hitting the page cache on the OSD node(s) or the librbd cache.
The writes are even higher, are you using the "direct=1" option in the Fio job?
>
> Pool replica - single
> pool 1 'test1' replicated size 1 min_size 1
>
> I have implemented rbd_readahead in my ceph conf file also.
> Any suggestions in this regard with help me..
>
> Thanks.
>
> Daleep Singh Bais
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