[3870] in linux-scsi channel archive
Re: [BACK ON TOPIC] SCSI & IDE (fwd)
daemon@ATHENA.MIT.EDU (Robert HYATT)
Thu May 7 23:18:12 1998
Date: Thu, 7 May 1998 21:25:33 -0500 (CDT)
From: Robert HYATT <hyatt@cis.uab.edu>
To: Bill Broadley <bill@math.UCDavis.edu>
cc: linux-scsi@vger.rutgers.edu, linux-smp@vger.rutgers.edu
In-Reply-To: <199805080041.RAA18951@proto.math.ucdavis.edu>
On Thu, 7 May 1998, Bill Broadley wrote:
> >I currently have a 4 processor P6/200 machine with UW scsi disks. I
> >recently had a dual-processor PII/300, but with IDE disks. We ran an
> >application on both that had a lot of computation, plus a lot of file
> >I/O. the SCSI system toasts the IDE system pretty badly. But for a
> >single-user machine, IDE isn't awful, just not as good as SCSI if you
> >have multiple disks...
>
> There are many variables here:
> Which parameters were you using with hdparm?
> Did you enable busmastering/dma?
> Were the block sizes the same on all disks?
> Which partition were you using (speed varies with where you
> are on the disk).
> Were you purely disk bound? Or are you seeing a difference between cpu's?
> 4 p6-200' are going to be alot faster then a dual pII-300 in alot of
> things, thats no surprise.
> How much memory on each system?
> Where kernel's?
> Were all the disks freshly formatted? Otherwise the layout of the files
> could largely effect the performance (both position and how contiguous
> they are).
> Which disks were involved on each? Same rpm? Same brand?
>
without making this complicated, the most noticable difference was
in a threaded application that read in 2 535mb files, massaged the
data, and wrote out 2 535mb new files. The SCSI drives are seagate
4.3 gig UW drives. The IDE's were fireballs I believe. the problem
seemed to be reading/writing at the same time, as this threaded app
was doing...
It was substantially faster on the scsi drives.
I'll have to go dig up config data more detailed, as that PII/300X2 was
just a loaner for evauation and is gone...
>
>
> --
> Bill Broadley Bill@math.ucdavis.edu UCD Math Sys-Admin
> Linux is great. http://math.ucdavis.edu/~bill PGP-ok
>
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