Only certain SSD's are good for CEPH Journals as can be seen @ https://www.sebastien-han.fr/blog/2014/10/10/ceph-how-to-test-if-your-ssd-is-suitable-as-a-journal-device/
The SSD your using isn't listed but doing a quick search online it appears to be a SSD designed for read workloads as a "upgrade" from a HD so probably is not designed for the high write requirements a journal demands. Therefore when it's been hit by 3 OSD's of workloads your not going to get much more performance out of it than you would just using the disk as your seeing. On Wed, Nov 14, 2018 at 12:21 PM <dave.c...@dell.com> wrote: > Hi all, > > > > We want to compare the performance between HDD partition as the journal > (inline from OSD disk) and SSD partition as the journal, here is what we > have done, we have 3 nodes used as Ceph OSD, each has 3 OSD on it. > Firstly, we created the OSD with journal from OSD partition, and run “rados > bench” utility to test the performance, and then migrate the journal from > HDD to SSD (Intel S4500) and run “rados bench” again, the expected result > is SSD partition should be much better than HDD, but the result shows us > there is nearly no change, > > > > The configuration of Ceph is as below, > > pool size: 3 > > osd size: 3*3 > > pg (pgp) num: 300 > > osd nodes are separated across three different nodes > > rbd image size: 10G (10240M) > > > > The utility I used is, > > rados bench -p rbd $duration write > > rados bench -p rbd $duration seq > > rados bench -p rbd $duration rand > > > > Is there anything wrong from what I did? Could anyone give me some > suggestion? > > > > > > Best Regards, > > Dave Chen > > > _______________________________________________ > ceph-users mailing list > ceph-users@lists.ceph.com > http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com >
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