[3757] in linux-scsi channel archive
Re: LINUX source code
daemon@ATHENA.MIT.EDU (Zlatko Calusic)
Fri Apr 24 09:38:04 1998
To: Ian Stirling <root@mauve.demon.co.uk>
Cc: linux-scsi@vger.rutgers.edu
Reply-To: Zlatko.Calusic@CARNet.hr
From: Zlatko Calusic <Zlatko.Calusic@CARNet.hr>
Date: 24 Apr 1998 13:50:51 +0200
In-Reply-To: Ian Stirling's message of "Thu, 23 Apr 1998 22:45:54 +0100 (BST)"
Ian Stirling <root@mauve.demon.co.uk> writes:
> <snip>
> > I found that WDC AC22000L IDE UDMA 2GB drive (5400rpm) is slightly
> > _faster_ than Fujitsu M2954ESP UltraSCSI 4GB drive (7200!rpm). How can
> > it be???
> >
> > My setup: Linux v2.1.97, glibc, P166MMX, 32MB RAM, Adaptec 2940UW.
> >
> > SCSI:
> > -------Sequential Output-------- ---Sequential Input-- --Random--
> > -Per Char- --Block--- -Rewrite-- -Per Char- --Block--- --Seeks---
> > Machine MB K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU /sec %CPU
> > 100 1614 76.3 5607 27.7 2440 23.4 1638 71.2 6583 25.3 92.4 3.9
> > ^^^^ ^^^^
>
> Ahh, but look at the seeks ^
>
> > UDMA:
> > -------Sequential Output-------- ---Sequential Input-- --Random--
> > -Per Char- --Block--- -Rewrite-- -Per Char- --Block--- --Seeks---
> > Machine MB K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU /sec %CPU
> > 100 1564 74.2 7443 42.2 2815 28.8 1766 76.5 8092 35.2 69.8 2.6
> > ^^^^ ^^^^
> >
> ^
>
> The rotational speed has little to do with the transfer speed, unless
> all other things are exactly equal.
> What are you using to measure that?
> I get 10.5Mb/sec using quantum bigfoot 8Gb, (hdparm -t) and my brother reports
> 15Mbish with a fuji drive.
> Both TX motherboards.
>
>
Well, yes, SCSI drive is seeking faster, but shouldn't higher
rotational speed also read data faster from the media?
What bothers me is that many people report speeds of >= 10MB/s with
their drives (even cheaper IDE ones) and it seems I can't get more
than around 7MB/s with so called Enterprise UW SCSI drive with big
capacity and high rotational speed???
I made above tests with "bonnie" program. Altavista is your friend. :)
Testing with hdparm -t:
{atlas} [~]# hdparm -t /dev/sda
/dev/sda:
Timing buffered disk reads: 32 MB in 3.71 seconds = 8.63 MB/sec
{atlas} [~]# hdparm -t /dev/hda
/dev/hda:
Timing buffered disk reads: 32 MB in 3.70 seconds = 8.65 MB/sec
{atlas} [~]# hdparm -t /dev/sda
??????
I probably don't need to mention that the SCSI drive costs much more
than the IDE one. SCSI controller is another story. :)
Bye!
--
Posted by Zlatko Calusic E-mail: <Zlatko.Calusic@CARNet.hr>
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