On 10/5/09 10:27 AM, "Karl Denninger" <karl@xxxxxxxxxxxxx> wrote: > Scott Carey wrote: >> >> >> On 10/3/09 7:35 PM, "Karl Denninger" <karl@xxxxxxxxxxxxx> >> <mailto:karl@xxxxxxxxxxxxx> wrote: >> >> >> >>> >>> I am a particular fan of FreeBSD, and in some benchmarking I did between it >>> and CentOS FreeBSD 7.x literally wiped the floor with the CentOS release I >>> tried on IDENTICAL hardware. >>> I also like the 3ware raid coprocessors - they work well, are fast, and I've >>> had zero trouble with them. >>> >>> -- Karl >>> >>> >> >> >> With CentOS 5.x, I have to do quite a bit of tuning to get it to perform >> well. I often get almost 2x the performance after tuning. >> >> For I/O -- >> Deadline scheduler + reasonably large block device read-ahead + XFS >> configured with large 'allocsize' settings (8MB to 80MB) make a huge >> difference. >> >> Furthermore, the 3ware 35xx and 36xx (I think) I tried performed >> particularly badly out of the box without tuning on CentOS. >> >> So, Identical hardware or not, both have to be tuned well to really compare >> anyway. >> >> However, I have certainly seen some inefficiencies with Linux and large use >> of shared memory -- and I wouldn't be surprised if these problems don't >> exist on FreeBSD or OpenSolaris. >> > I don't run the 3x series 3ware boards. If I recall correctly they're not > true coprocessor boards and rely on the host CPU. Those are always going to > be a lose compared to a true coprocessor with dedicated cache memory on the > card. I screwed up, it was the 95xx and 96xx that stink for me. (Adaptec 2x as fast, PERC 6 25% faster) with 1TB SATA drives. Thought 96xx was a good chunk faster due to the faster interface. > > The 9xxx series boards are, and are extremely fast (make sure you install the > battery backup or run on a UPS, set the appropriate flags, and take your > chances - writeback caching makes a HUGE difference.) Not at all in my experience, 12 drives in raid 10, and 300MB/sec sequential trasfer rate = crap. Heavily tweaked, 450MB/sec. (Adaptec 5805 = 600MB/sec). > > Other than pinning shared memory on FreeBSD (and increasing a couple of > boot-time tunables to permit large enough shared segments and semaphore lists) > little is required to get excellent performance. > > The LSI cards that DELL, Intel and a few others have used (these appear to be > deprecated now as it looks like LSI bought 3ware) also work well but their > user interface is somewhat of a pain in the butt compared to 3Ware's. > > -- Karl > -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
