I am not sure about the enterprise grade and underprovisioning, but for the Intel 520s i've got 240gbs (the speeds of 240 is a bit better than 120s). and i've left 50% underprovisioned. I've got 10GB for journals and I am using 4 osds per ssd.
Andrei ----- Original Message ----- > From: "Tony Harris" <neth...@gmail.com> > To: "Andrei Mikhailovsky" <and...@arhont.com> > Cc: ceph-users@lists.ceph.com, "Christian Balzer" <ch...@gol.com> > Sent: Sunday, 1 March, 2015 8:49:56 PM > Subject: Re: [ceph-users] SSD selection > 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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