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Re: high load on heavy disk i/o

daemon@ATHENA.MIT.EDU (Ronald Wahl)
Mon Sep 27 21:50:52 1999

Date:   Tue, 28 Sep 1999 03:47:45 +0200 (CEST)
From:   Ronald Wahl <rwahl@gmx.net>
To:     linux-scsi <linux-scsi@vger.rutgers.edu>
In-Reply-To: <Pine.LNX.4.10.9909272246350.607-100000@goliath.csn.tu-chemnitz.de>
Message-ID: <Pine.LNX.4.10.9909280338290.1027-100000@goliath.csn.tu-chemnitz.de>
MIME-Version: 1.0
Content-Type: TEXT/PLAIN; charset=US-ASCII

On Mon, 27 Sep 1999, Ronald Wahl wrote:

> Hi,
> 
> after installing a new disk (IBM DNES-309170W U2W SE/LVD - was cheaper
> than the UW model :-) on my SYMBIOS Controller (sym53c875 rev. 4). I
> noticed that during heavy disk i/o (e.g. creating a cdrom image or doing
> "cat /dev/zero > some_file") the load goes up to 3 or more and the system
> becomes totally unusable. Mostly all programs called during this time
> starting after the i/o load is gone. First I thought it was the cable
> length since it was 2m in length and ultra scsi spec doesn't allow greater
> than 1.5m in my case. Both ends are are terminated (active). I even had
> some wrong data during transfer (but very seldom). So I shorted my narrow
> cable to fit the spec. But at least the problem with the heavy load and
> system unusability is still there. Without this new disk I had no such
> problems. What's the problem here?
> <...>

The following may be relevant: mke2fs created most of my partions with a
blocksize of 4096 bytes (which seems to speed things greatly up!). Maybe
the driver has a problem with this greater blocks. I have similar
problems (high load, system unusable) with my MO drive which uses 2048
byte blocks (even under 2.0.36 this was a problem). 

ron

-- 
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