I see Sun has recently released part number XRA-ST1CH-32G2SSD, a 32GB SATA SSD for the x4540 server.
We have five x4500's we purchased last year that we are deploying to provide file and web services to our users. One issue that we have had is horrible performance for the "single threaded process creating lots of small files over NFS" scenario. The bottleneck in that case is fairly clear, and to verify it we temporarily disabled the ZIL on one of the servers. Extraction time for a large tarball into an NFSv4 mounted filesystem dropped from 20 minutes to 2 minutes. Obviously, it is strongly recommended not to run with the ZIL disabled, and we don't particularly want to do so in production. However, for some of our users, performance is simply unacceptable for various usage cases (including not only tar extracts, but other common software development processes such as svn checkouts). As such, we have been investigating the possibility of improving performance via a slog, preferably on some type of NVRAM or SSD. We haven't really found anything appropriate, and now we see Sun has officially released something very possibly like what we have been looking for. My sales rep tells me the drive is only qualified for use in an x4540. However, as a standard SATA interface SSD there is theoretically no reason why it would not work in an x4500, they even share the exact same drive sleds. I was told Sun just didn't want to spend the time/effort to qualify it for the older hardware (kind of sucks that servers we bought less than a year ago are being abandoned). We are considering using them anyway, in the worst case if Sun support complains that they are installed and refuses to continue any diagnostic efforts, presumably we can simply swap them out for standard hard drives. slog devices can be replaced like any other zfs vdev, correct? Or alternatively, what is the state of removing a slog device and reverting back to a pool embedded log? So, has anyone played with this new SSD in an x4500 and can comment on whether or not they seemed to work okay? I can't imagine no one inside of Sun, regardless of official support level, hasn't tried it :). Feel free to post anonymously or reply off list if you don't want anything on the record ;). >From reviewing the Sun hybrid storage documentation, it describes two different flash devices, the "Logzilla", optimized for blindingly fast writes and intended as a ZIL slog, and the "Cachezilla", optimized for fast reads and intended for use as L2ARC. Is this one of those, or some other device? If the latter, what are its technical read/write performance characteristics? We currently have all 48 drives allocated, 23 mirror pairs and two hot spares. Is there any timeline on the availability of removing an active vdev from a pool, which would allow us to swap out a couple of devices without destroying and having to rebuild our pool? What is the current state of behavior in the face of slog failure? Theoretically, if a dedicated slog device failed, the pool could simply revert to logging embedded in the pool. However, the last I heard slog device failure rendered a pool completely unusable and inaccessible. If that is still the case and not expected to be resolved anytime soon, we would presumably need two of the devices to mirror? Thanks for any info you might be able to provide. -- Paul B. Henson | (909) 979-6361 | http://www.csupomona.edu/~henson/ Operating Systems and Network Analyst | hen...@csupomona.edu California State Polytechnic University | Pomona CA 91768 _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
