Wood, Russell wrote: > I have an LSI MegaRaid with three drives at RAID 5: works a > god-damn-treat. I don't know what my throughput is on RAID 5 but RAID 0 > was fast (70MB/s+).
Mine was RAID5. Hmm, oops, it wasn't LSI but HP/Compaq CISS, battery backed, SATA on SAS. da0 at ciss0 bus 0 target 0 lun 0 da0: <COMPAQ RAID 5 VOLUME OK> Fixed Direct Access SCSI-0 device da0: 135.168MB/s transfers da0: 476886MB (976662896 512 byte sectors: 255H 32S/T 65535C) > Were you doing these tests a few hours after initializing the array, by > any chance? If so, then the poor performance could be because the array > was `in build' while you were using it, and therefore you'd get very > poor performance. Yes, I observed BIOS status. Here's a typical run of bonnie++: Version 1.93c ------Sequential Output------ --Sequential Input- --Random- Concurrency 1 -Per Chr- --Block-- -Rewrite- -Per Chr- --Block-- --Seeks-- Machine Size K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec %CP /sec %CP xxx.com 2500M 358 99 13446 4 7068 2 559 96 97548 23 300.0 10 Latency 23236us 848ms 488ms 191ms 214ms 175ms My reading of iostat during 'dd' is that writes perform good until the on-controller cache gets filled, then it slows down: tty da0 pass0 cpu tin tout KB/t tps MB/s KB/t tps MB/s us ni sy in id ... 0 60 0.00 0 0.00 0.00 0 0.00 0 0 0 0 100 1 64 127.93 217 27.08 0.00 0 0.00 0 0 5 0 95 0 61 125.92 400 49.14 0.00 0 0.00 0 0 2 1 98 0 61 128.00 107 13.36 0.00 0 0.00 0 0 2 0 98 0 61 128.00 107 13.36 0.00 0 0.00 0 0 2 0 98 0 61 128.00 104 12.99 0.00 0 0.00 0 0 2 0 98 Cache size is 128MB, 75% dedicated to write caching.
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