On Fri, 02 Jan 2015 06:38:49 +1000 Lindsay Mathieson wrote: > Expanding my tiny ceph setup from 2 OSD's to six, and two extra SSD's > for journals (IBM 530 120GB) > > Yah, I know the 5300's would be much better .... > S5700's really, if you look at the prices and especially TBW/$. > Assuming I use 10GB ber OSD for journal and 5GB spare to improve the SSD > lifetime, that leaves 85GB spare per SSD. > > > Is it worthwhile setting up a 2 *85GB OSD Cache Tier (Replica 2)? Usage > is for approx 15 Active VM's, used mainly for development and light > database work. > If you research the ML archives you will find that cache tiering currently isn't just fraught with peril (there are bugs) but most importantly isn't really that fast. You're likely better off making this a dedicated pool for DB storage, etc. Note that getting even a fraction of the performance of those SSDs will require quite a lot of CPU power. Also given your setup, you should be able to saturate your network now, so probably negating the need for super fast storage to some extent. Christian -- Christian Balzer Network/Systems Engineer chibi@xxxxxxx Global OnLine Japan/Fusion Communications http://www.gol.com/ _______________________________________________ ceph-users mailing list ceph-users@xxxxxxxxxxxxxx http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
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