Re: [TCLUG:22248] Adaptec scsi performance

[Michael Josephson <mjj55409@yahoo.com>]

On Thu, Oct 05, 2000 at 04:06:01PM -0500, Ben Kochie wrote:
> yep.. that's about normal.. you are hitting DISK preformance limits.. not
> chain limits.. here's what I get on a 10k RPM disk on an alpha 600 with a
> symbios card.. you are also hitting the PCI bus limit of 133MB.  this is
> an active box.. so the numbers are a little low :( (load is about 2 right
> now)
> 
>  Timing buffered disk reads:  64 MB in  3.53 seconds = 18.13 MB/sec
>  Timing buffer-cache reads:   128 MB in  3.06 seconds = 41.80 MB/sec
> 
> that's for normal UltraWide
> 
> this one is a K6-2 450, with a buslogic (mylex) scsi card, and a 7200 RPM
> disk (i think) (backup server, no load)
> 
>  Timing buffered disk reads:  64 MB in  5.54 seconds = 11.55 MB/sec
>  Timing buffer-cache reads:   128 MB in  3.28 seconds = 39.02 MB/sec
> 
> and finaly, a dual celeron with a 7200 RPM ide drive
> 
>  Timing buffered disk reads:  64 MB in  3.47 seconds = 18.44 MB/sec
>  Timing buffer-cache reads:   128 MB in  1.49 seconds = 85.91 MB/sec
> 
> all drives are fairly recent (less than 1 year old) IBM ultrastars, and
> IDE is a deskstar.
> 
> On Thu, 5 Oct 2000, Michael Josephson wrote:
> 
> > I'm running Debian (kernal 2.2.17) on a server at
> > home: PIII 700 256MB ram with an Adaptec 29160 SCSI
> > controller and an IBM ultra 160 hard drive. When I run
> > hdparm -Tt /dev/sda, it reports:
> > 
> > Timing buffer-cache reads: ...= 128 MB/sec
> > Timing buffered disk reads: ...= 19.05 MB/sec
> > 
> > I'm not expecting max performance, but 19 MB/sec is a
> > helluva lot slower than 160 MB/sec. Anyone have any
> > thoughts on this?
---end quoted text---

I've got a new IBM ultrastar 7200rpm (purchased in June). The box currently
has no load. According to your numbers, I should be getting at least twice
the 19MB/sec. 

I'm not too worried about this. But I'm trying to understand as much as I can
about the hardware...I'm a programmer, not a doctor :-) I haven't noticed any
performance issues, but the results of hdparm indicates to me that things could
use some tuning.

mj
-- 
  Michael Josephson
  Software Development/Web Administration
  mjj@mjjtech.net
  www.mjjtech.net