Hi I have been testing the Samsung 840 Pro (128gb) for quite sometime and I can also confirm that this drive is unsuitable for osd journal. The performance and latency that I get from these drives (according to ceph osd perf) are between 10 - 15 times slower compared to the Intel 520. The Intel 530 drives are also pretty awful. They are meant to be a replacement of the 520 drives, but the performance is pretty bad.
I have found Intel 520 to be a reasonable drive for performance per price, for a cluster without a great deal of writes. However they do not make those anymore. Otherwise, it seems that the Intel 3600 and 3700 series is a good performer and has a much longer life expectancy. Andrei ----- Original Message ----- > From: "Eneko Lacunza" <[email protected]> > To: "J-P Methot" <[email protected]>, "Christian Balzer" > <[email protected]>, [email protected] > Sent: Tuesday, 21 April, 2015 8:18:20 AM > Subject: Re: [ceph-users] Possible improvements for a slow write > speed (excluding independent SSD journals) > Hi, > I'm just writing to you to stress out what others have already said, > because it is very important that you take it very seriously. > On 20/04/15 19:17, J-P Methot wrote: > > On 4/20/2015 11:01 AM, Christian Balzer wrote: > >> > >>> This is similar to another thread running right now, but since > >>> our > >>> current setup is completely different from the one described in > >>> the > >>> other thread, I thought it may be better to start a new one. > >>> > >>> We are running Ceph Firefly 0.80.8 (soon to be upgraded to > >>> 0.80.9). We > >>> have 6 OSD hosts with 16 OSD each (so a total of 96 OSDs). Each > >>> OSD > >>> is a > >>> Samsung SSD 840 EVO on which I can reach write speeds of roughly > >>> 400 > >>> MB/sec, plugged in jbod on a controller that can theoretically > >>> transfer > >>> at 6gb/sec. All of that is linked to openstack compute nodes on > >>> two > >>> bonded 10gbps links (so a max transfer rate of 20 gbps). > >>> > >> I sure as hell hope you're not planning to write all that much to > >> this > >> cluster. > >> But then again you're worried about write speed, so I guess you > >> do. > >> Those _consumer_ SSDs will be dropping like flies, there are a > >> number of > >> threads about them here. > >> > >> They also might be of the kind that don't play well with O_DSYNC, > >> I > >> can't > >> recall for sure right now, check the archives. > >> Consumer SSDs universally tend to slow down quite a bit when not > >> TRIM'ed > >> and/or subjected to prolonged writes, like those generated by a > >> benchmark. > > I see, yes it looks like these SSDs are not the best for the job. > > We > > will not change them for now, but if they start failing, we will > > replace them with better ones. > I tried to put a Samsung 840 Pro 256GB in a ceph setup. It is > supposed > to be quite better than the EVO right? It was total crap. No "not the > best for the job". TOTAL CRAP. :) > It can't give any useful write performance for a Ceph OSD. Spec sheet > numbers don't matter for this, they don't work for ceph OSD, period. > And > yes, the drive is fine and works like a charm in workstation > workloads. > I suggest you at least get some intel S3700/S3610 and use them for > the > journal of those samsung drives, I think that could help performance > a lot. > Cheers > Eneko > -- > Zuzendari Teknikoa / Director Técnico > Binovo IT Human Project, S.L. > Telf. 943575997 > 943493611 > Astigarraga bidea 2, planta 6 dcha., ofi. 3-2; 20180 Oiartzun > (Gipuzkoa) > www.binovo.es > _______________________________________________ > ceph-users mailing list > [email protected] > http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
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