In the last episode (Jan 23), Rishi Chopra said: > I've run some imperical tests on the Adaptec 2400A raid controller > (results and setup can be seen here): > > http://www.ocf.berkeley.edu/~rchopra/RaidResults.html > > I was rather disappointed with the results. Can anyone suggest what > might be causing such slow disk speeds, or whether these speeds are > out of the ordinary for a 4-disk FreeBSD RAID5 installation? I have > done nothing to configure the card aside from striping the array in > BIOS; FreeBSD seems to automatically detect the disks. > > I once ran a 2-disk RAID-0 installation on Win2k which was 6-7 times > faster on sequential read/write tests (60-70MB/sec), hence my dismay.
RAID-5 has to do 4 I/Os for every write, which would explain the bad write performance, but I can't explain your read performance. It's not strictly comparable, but a Raid-5 4x73gb SCSI setup using an Adaptec 3200S (128MB cache), which looks like it uses the same RAID engine and firmware as your 2400A, averages 18MB/sec writes and 50MB/sec reads. Your card configured with a RAID 0 volume should equal your w2k speeds. -- Dan Nelson [EMAIL PROTECTED] _______________________________________________ [EMAIL PROTECTED] mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to "[EMAIL PROTECTED]"