Hi,
in our quest to get the right SSD for OSD journals, I managed to
benchmark two kind of "10 DWPD" SSDs :
- Toshiba M2 PX02SMF020
- Samsung 845DC PRO
I wan't to determine if a disk is appropriate considering its absolute
performances, and the optimal number of ceph-osd processes using the SSD
as a journal.
The benchmark consists of a fio command, with SYNC and DIRECT access
options, and 4k blocks write accesses.
fio --filename=/dev/sda --direct=1 --sync=1 --rw=write --bs=4k
--runtime=60 --time_based --group_reporting --name=journal-test
--iodepth=<1 or 16> --numjobs=< ranging from 1 to 16>
I think numjobs can represent the concurrent number of OSD served by
this SSD. Am I right on this ?
http://www.4shared.com/download/WOvooKVXce/Fio-Direct-Sync-ToshibaM2-Sams.png?lgfp=3000
My understanding of that data is that the 845DC Pro cannot be used for
more that 4 OSD.
The M2 is very constant in its comportment.
The iodepth has almost no impact on perfs here.
Could someone having other SSD types make the same test to consolidate
the data ?
Among the short list that could be considered for that task (for their
price/perfs/DWPD/...) :
- Seagate 1200 SSD 200GB, SAS 12Gb/s ST200FM0053
- Hitachi SSD800MM MLC HUSMM8020ASS200
- Intel DC3700
I've not yet considered write amplification mentionned in other posts.
Frederic
Josef Johansson <jose...@gmail.com> a écrit le 20/03/15 10:29 :
The 845DC Pro does look really nice, comparable with s3700 with TDW even.
The price is what really does it, as it’s almost a third compared with s3700..
_______________________________________________
ceph-users mailing list
ceph-users@lists.ceph.com
http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
