Thanks Jens, I have a vdbench profile and script that will run the new SNIA Solid State Storage (SSS) Performance Test Suite (PTS). I'd be happy to share if anyone is interested. -- richard
On Jul 28, 2011, at 7:10 AM, Jens Elkner wrote: > Hi, > > Roy Sigurd Karlsbakk wrote: >> Crucial RealSSD C300 has been released and showing good numbers for use as >> Zil and L2ARC. Does anyone know if this unit flushes its cache on request, >> as opposed to Intel units etc? >> > > I had a chance to get my hands on a Crucial RealSSD C300/128MB yesterday and > did > some quick testing. Here are the numbers first, some explanation follows > below: > > cache enabled, 32 buffers: > Linear read, 64k blocks: 134 MB/s > random read, 64k blocks: 134 MB/s > linear read, 4k blocks: 87 MB/s > random read, 4k blocks: 87 MB/s > linear write, 64k blocks: 107 MB/s > random write, 64k blocks: 110 MB/s > linear write, 4k blocks: 76 MB/s > random write, 4k blocks: 32 MB/s > > cache enabled, 1 buffer: > linear write, 4k blocks: 51 MB/s (12800 ops/s) > random write, 4k blocks: 7 MB/s (1750 ops/s) > linear write, 64k blocks: 106 MB/s (1610 ops/s) > random write, 64k blocks: 59 MB/s (920 ops/s) > > cache disabled, 1 buffer: > linear write, 4k blocks: 4.2 MB/s (1050 ops/s) > random write, 4k blocks: 3.9 MB/s (980 ops/s) > linear write, 64k blocks: 40 MB/s (650 ops/s) > random write, 64k blocks: 40 MB/s (650 ops/s) > > cache disabled, 32 buffers: > linear write, 4k blocks: 4.5 MB/s, 1120 ops/s > random write, 4k blocks: 4.2 MB/s, 1050 ops/s > linear write, 64k blocks: 43 MB/s, 680 ops/s > random write, 64k blocks: 44 MB/s, 690 ops/s > > cache enabled, 1 buffer, with cache flushes > linear write, 4k blocks, flush after every write: 1.5 MB/s, 385 writes/s > linear write, 4k blocks, flush after every 4th write: 4.2 MB/s, 1120 writes/s > > > The numbers are rough numbers read quickly from iostat, so please don't > multiply block size by ops and compare with the bandwidth given ;) > The test operates directly on top of LDI, just like ZFS. > - "nk blocks" means the size of each read/write given to the device driver > - "n buffers" means the number of buffers I keep in flight. This is to keep > the command queue of the device busy > - "cache flush" means a synchronous ioctl DKIOCFLUSHWRITECACHE > > These numbers contain a few surprises (at least for me). The biggest surprise > is that with cache disabled one cannot get good data rates with small blocks, > even if one keeps the command queue filled. This is completely different from > what I've seen from hard drives. > Also the IOPS with cache flushes is quite low, 385 is not much better than > a 15k hdd, while the latter scales better. On the other hand, from the large > drop in performance when using flushes one could infer that they indeed flush > properly, but I haven't built a test setup for that yet. > > Conclusion: From the measurements I'd infer the device makes a good L2ARC, > but for a slog device the latency is too high and it doesn't scale well. > > I'll do similar tests on a x-25 and ocz vertex 2 pro as soon as they arrive. > > If there are numbers you are missing please tell me, I'll measure them if > possible. Also please ask if there are questions regarding the test setup. > > -- > Arne > _______________________________________________ > zfs-discuss mailing list > zfs-discuss@opensolaris.org > http://mail.opensolaris.org/mailman/listinfo/zfs-discuss _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
