[3761] in linux-scsi channel archive
Re: LINUX source code
daemon@ATHENA.MIT.EDU (Zlatko Calusic)
Fri Apr 24 18:45:20 1998
To: "Larry M. Augustin" <lma@varesearch.com>
Cc: Ian Stirling <root@mauve.demon.co.uk>, linux-scsi@vger.rutgers.edu
Reply-To: Zlatko.Calusic@CARNet.hr
From: Zlatko Calusic <Zlatko.Calusic@CARNet.hr>
Date: 24 Apr 1998 20:23:35 +0200
In-Reply-To: "Larry M. Augustin"'s message of "Fri, 24 Apr 1998 11:01:03 -0700"
"Larry M. Augustin" <lma@varesearch.com> writes:
> There's a lot more to getting good performance out of a drive than
> just the seek time and rotational speed. Consider:
>
> rpm buffer avg seek t-t seek internal transfer
> Fujitsu M2954ESP 7200 506K 8.0ms 0.8ms 9.9-14.0 MB/sec
> Seagate Cheetah 10,000 2M 8.2ms 0.8ms 15.25-22.1 MB/sec
>
> The Fujitsu web page doesn't say if their internal transfer rate is
> formatted or unformatted. But either way it is on the low side. The
> 7200 Atlas II has internal transfer rates up to 22.5MB/sec. The 506K
> buffer seems like a strange size. I would think you would want at
> least a full sector buffered. The Cheetahs are available with up to
> 2MB buffer, and the Atlas III has 1MB. I usually take about 70% of
> the average internal transfer speed and expect that to be close to the
> bonnie/iozone numbers. For the Fujitsu that's 8365. For the Cheetah
> that's 13000, which is about what we see in benchmarks.
>
> The hdparm results you get for the Fujitsu seem about right.
>
> Bottom line: I'd expect your Fujitsu drive to get about 8MB/s
> sequential block input numbers, and you're seeing close to that with
> hdparm. Maybe there's something else wrong in your setup (I'd like to
> try the Fujitsu disk on a fast PII with a real SCSI controller), but
> the Fujitsu M2954ESP doesn't look like its going to be a performance
> leader.
>
Well, that's about all I wanted to hear.
Thinking for a long time the only thing I was certain about is that
Fujitsu lacks some final improvements that are incorporated in the
latest high performance drives. Looks like we are speaking of internal
transfer rate here.
Nevertheless, I was quite happy until I replaced ye good old P133
(with IBM IDE 3.2GB) with P166MMX which came with WD DMA 2GB drive.
Only then I started to be jealous of new IDE drive, since it has
slightly higher raw transfer rate. Of course, SCSI is still better
since it seeks much faster, but... :)
BTW, Fujitsu disk is original Sun's external drive.
So, I didn't have that much opportunities to choose among. :)
Regards from happy Linux user with nice setup!!!
--
Posted by Zlatko Calusic E-mail: <Zlatko.Calusic@CARNet.hr>
---------------------------------------------------------------------
P.S. Though that IDE drive could be little slower... :)
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