Hello, On Mon, 29 Feb 2016 15:00:08 -0800 Heath Albritton wrote:
> > Did you just do these tests or did you also do the "suitable for Ceph" > > song and dance, as in sync write speed? > > These were done with libaio, so async. I can do a sync test if that > helps. My goal for testing wasn't specifically suitability with ceph, > but overall suitability in my environment, much of which uses async > IO. > Fair enough. Sync tests would be nice, if nothing else to confirm that the Samsung DC level SSDs are suitable and how they compare in that respect to the Intels. > > >> SM863 Pro (default over-provisioning) ~7k IOPS per thread (4 threads, > >> QD32) Intel S3710 ~10k IOPS per thread > >> 845DC Pro ~12k IOPS per thread > >> SM863 (28% over-provisioning) ~18k IOPS per thread > >> > > Very interesting. > > To qualify your values up there, could you provide us with the exact > > models, well size of the SSD will do. > > SM863 was 960GB, I've many of these and the 1.92TB models deployed > 845DC Pro, 800GB > S3710, 800GB > Thanks, pretty much an oranges with oranges comparison then. ^o^ > > Also did you test with a S3700 (I find the 3710s to be a slight > > regression in some ways)? > > And for kicks, did you try over-provisioning with an Intel SSD to see > > the effects there? > > These tests were performed mid-2015. I requested an S3700, but at > that point, I could only get the S3710. I didn't test the Intel with > increased over-provisioning. I suspect it wouldn't have performed > much better as it was already over-provisioned by 28% or thereabouts. > Yeah, my curiosity was mostly if there is similar ratio at work here (might have made more sense for testing purposes to REDUCE the overprovisioning of the Intel) and where the point of diminishing returns is. > It's easy to guess at these sort of things. The total capacity of > flash is in some power of two and the advertised capacity is some > power of ten. Manufacturer's use the difference to buy themselves > some space for garbage collection. So, a terabyte worth of flash is > 1099511627776 bytes. 800GB is 8e+11 bytes with the difference of > about 299GB, which is the space they've set aside for GC. > Ayup, that I was quite aware of. > Again, if there's some tests you'd like to see done, let me know. > It's relatively easy for me to get samples and the tests are a benefit > to me as much as any other. > Well, see above, diminishing returns and all. > > >> I'm seeing the S3710s at ~$1.20/GB and the SM863 around $.63/GB. As > >> such, I'm buying quite a lot of the latter. > > > > I assume those numbers are before over-provisioning the SM863, still > > quite a difference indeed. > > Yes, that's correct. Here's some current pricing: Newegg has the > SM863 960GB at $565 or ~$.59/GB raw. With 28% OP, that yields around > 800GB and around $.71/GB > If I'm reading the (well hidden and only in the PDF) full specs of the 960GB 863 correctly it has an endurance of about 3 DWPD, so the comparable Intel model would be the 3610s. At least when it comes to endurance. Would be interesting to see those two in comparison. ^.^ > >> I've not had them deployed > >> for very long, so I can't attest to anything beyond my synthetic > >> benchmarks. I'm using the LSI 3008 based HBA as well and I've had to > >> use updated firmware and kernel module for it. I haven't checked the > >> kernel that comes with EL7.2, but 7.1 still had problems with the > >> included driver. > >> > > Now THIS is really interesting. > > As you may know several people on this ML including me have issues with > > LSI 3008s and SSDs, including Samsung ones. > > > > Can you provide all the details here, as in: > > IT or IR mode (IT I presume) > > Firmware version > > Kernel driver version > > When initially deployed about a year ago, I had problems with SSDs and > spinning disks. Not sure about any problems specific to Samsung SSDs, > but I've been on the upgrade train. > > I think the stock kernel module is 4.x something or other and LSA, now > Avago has released P9 through P12 in the past year. When I first > started using them, I was on the P9 firmware and kernel module, which > I built from the sources they supply. At this point most of my infra > is on the P10 version. I've not tested the later versions. > > Everything is IT mode where possible. > Yes, at least until kernel 4.1 the module was the 4.0 version. And I had no luck at all getting the newer versions into a generic kernel or Debian. And when I deployed the machines in question P8 was the latest FW from Supermicro. Kernel 4.4 does have the 9.x module, so I guess that's a way forward at least on the kernel side of things (which I think is the more likely culprit). Thanks, Christian -- Christian Balzer Network/Systems Engineer ch...@gol.com Global OnLine Japan/Rakuten Communications http://www.gol.com/ _______________________________________________ ceph-users mailing list ceph-users@lists.ceph.com http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
