Ok, any size suggestion? Can I get a 120 and be ok? I see I can get DCS3500 120GB for within $120/drive so it's possible to get 6 of them...
-Tony On Sun, Mar 1, 2015 at 12:46 PM, Andrei Mikhailovsky <and...@arhont.com> wrote: > > I would not use a single ssd for 5 osds. I would recommend the 3-4 osds > max per ssd or you will get the bottleneck on the ssd side. > > I've had a reasonable experience with Intel 520 ssds (which are not > produced anymore). I've found Samsung 840 Pro to be horrible! > > Otherwise, it seems that everyone here recommends the DC3500 or DC3700 and > it has the best wear per $ ratio out of all the drives. > > Andrei > > > ------------------------------ > > *From: *"Tony Harris" <neth...@gmail.com> > *To: *"Christian Balzer" <ch...@gol.com> > *Cc: *ceph-users@lists.ceph.com > *Sent: *Sunday, 1 March, 2015 4:19:30 PM > *Subject: *Re: [ceph-users] SSD selection > > > Well, although I have 7 now per node, you make a good point and I'm in a > position where I can either increase to 8 and split 4/4 and have 2 ssds, or > reduce to 5 and use a single osd per node (the system is not in production > yet). > > Do all the DC lines have caps in them or just the DC s line? > > -Tony > > On Sat, Feb 28, 2015 at 11:21 PM, Christian Balzer <ch...@gol.com> wrote: > >> On Sat, 28 Feb 2015 20:42:35 -0600 Tony Harris wrote: >> >> > Hi all, >> > >> > I have a small cluster together and it's running fairly well (3 nodes, >> 21 >> > osds). I'm looking to improve the write performance a bit though, which >> > I was hoping that using SSDs for journals would do. But, I was >> wondering >> > what people had as recommendations for SSDs to act as journal drives. >> > If I read the docs on ceph.com correctly, I'll need 2 ssds per node >> > (with 7 drives in each node, I think the recommendation was 1ssd per 4-5 >> > drives?) so I'm looking for drives that will work well without breaking >> > the bank for where I work (I'll probably have to purchase them myself >> > and donate, so my budget is somewhat small). Any suggestions? I'd >> > prefer one that can finish its write in a power outage case, the only >> > one I know of off hand is the intel dcs3700 I think, but at $300 it's >> > WAY above my affordability range. >> >> Firstly, an uneven number of OSDs (HDDs) per node will bite you in the >> proverbial behind down the road when combined with journal SSDs, as one of >> those SSDs will wear our faster than the other. >> >> Secondly, how many SSDs you need is basically a trade-off between price, >> performance, endurance and limiting failure impact. >> >> I have cluster where I used 4 100GB DC S3700s with 8 HDD OSDs, optimizing >> the write paths and IOPS and failure domain, but not the sequential speed >> or cost. >> >> Depending on what your write load is and the expected lifetime of this >> cluster, you might be able to get away with DC S3500s or even better the >> new DC S3610s. >> Keep in mind that buying a cheap, low endurance SSD now might cost you >> more down the road if you have to replace it after a year (TBW/$). >> >> All the cheap alternatives to DC level SSDs tend to wear out too fast, >> have no powercaps and tend to have unpredictable (caused by garbage >> collection) and steadily decreasing performance. >> >> Christian >> -- >> Christian Balzer Network/Systems Engineer >> ch...@gol.com Global OnLine Japan/Fusion Communications >> http://www.gol.com/ >> > > > _______________________________________________ > ceph-users mailing list > ceph-users@lists.ceph.com > http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com > > >
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