[lug] "Poor" RAID performance?

[Ferdinand Schmid]

For Reference - here is how one of my scsi disks performs on an Adaptec
29160N controller (Seagate 18 GB, 15kRPM disk - 1.5 years old).  Could
you test your setup with RAID-0 as a reference point?

Ferdinand

Sean Reifschneider wrote:
> 
> 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


              ---Sequential Output (nosync)--- ---Sequential Input--
--Rnd Seek-
              -Per Char- --Block--- -Rewrite-- -Per Char- --Block---
--04k (03)-
Machine    MB K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU  
/sec %CPU
pengui 1*2000 10799 60.4 21282 14.8 13275  5.9 15796 77.9 35328 10.6 
407.0  2.8



> 
> 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
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-- 
Ferdinand Schmid
Architectural Energy Corporation
Celebrating 20 Years of Improving Building Energy Performance
http://www.archenergy.com