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Re: Strange system behaviour when copying disks

To: Walt H <waltabbyh@xxxxxxxxxxx>
Subject: Re: Strange system behaviour when copying disks
From: Olaf Frączyk <olaf@xxxxxxxxxxxxx>
Date: 14 May 2003 17:50:48 +0200
Cc: linux-xfs@xxxxxxxxxxx
In-reply-to: <3EC25EE0.5000007@xxxxxxxxxxx>
References: <1052916810.2395.15.camel@venus> <3EC25EE0.5000007@xxxxxxxxxxx>
Sender: linux-xfs-bounce@xxxxxxxxxxx
On Wed, 2003-05-14 at 17:21, Walt H wrote:

> Do you have dma enabled on your IDE disks? I can't think of any reason
> off the top of my head why a cat from hda -> hdc should be affected by
> XFS, as you aren't using the filesystem for that - it's just reading the
> raw device. 
Yes, I know. I just don't know if XFS code changes some buffering etc.
Maybe with vanilla kernel it would be the same. I just have no easy way
to test it.
Make sure dma is enabled on hda and hdc and see if that
> helps:  hdparm -d1 /dev/hda /dev/hdc
Both drives have dma enabled.
And they are set to UDMA-100 also.

I'm just curious where from comes this terrible latency.



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