I was recently running some performance tests (bonnie++) on a RAID array
and was fairly suprised at the performance, or lack thereof... Since Rob
in the past has mentioned that current SCSI discs can saturate 80MB/sec
controllers, I'd assume that he's seeing something in that neighborhood.
The setup is a Mylex AcceleRAID 352 dual channel U160 controller, with 6
10KRPM drives set up in a RAID-5 array. According to the controller, all
drives are talking to the controller at 160MB/sec.
So, what is this "poor" performance?
------Sequential Output------ --Sequential Input- --Random-
-Per Chr- --Block-- -Rewrite- -Per Chr- --Block-- --Seeks--
Size K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec %CP /sec %CP
8000M 7089 56 7196 11 5969 5 12242 97 32905 21 381.1 3
Am I just expecting too much from a mid-end RAID setup? These numbers are
not all that much better (and are in some cases lower) than my laptop's
single 4500RPM IDE drive.
-Per Chr- --Block-- -Rewrite- -Per Chr- --Block-- --Seeks--
Size K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec %CP /sec %CP
700M 5508 82 15684 17 6775 5 4918 77 12615 5 90.4 0
For comparison sake, I've also run bonnie against 3 7200RPM IDE drives in a
RAID-0 array (though these drives were kind of mixed and matched, some at
least a year or two old -- not running the high bit densities seen
currently):
-Per Chr- --Block-- -Rewrite- -Per Chr- --Block-- --Seeks--
Size K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec %CP /sec %CP
2000 8616 78.3 49499 56.7 29567 35.2 10695 94.9 66362 36.1 237.5 2.1
Am I just wrong to be expecting a $3k RAID array to be faster than, say, a
laptop IDE drive?
Sean
--
"The big bad wolf, he learned the rule. You gotta get hot to play real cool."
Sean Reifschneider, Inimitably Superfluous <jafo at tummy.com>
tummy.com - Linux Consulting since 1995. Qmail, KRUD, Firewalls, Python