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Date: Fri, 4 Jan 2002 10:28:18 +0100 (CET)
From: Krzysztof Oledzki <ole@ans.pl>
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To: Mark Hahn <hahn@physics.mcmaster.ca>
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Subject: Re: Two hdds on one channel - why so slow?
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On Wed, 2 Jan 2002, Mark Hahn wrote:

>
> yes, I know what he said.  it's true that there's no concurrency,
> but he's wrong about expecting half (due to readahead/writebehind),
> and there's no real overhead in switching.
So why my disks work with ~12MB/sec per device (~24 per channel) when
both HDDs are accessed on the sime time?

> in short, master-slave concurrency is not common (but definitely
> supported by the standard and some disks), but this has less
> effect than you'd think.  especially since most people just
> treat ide as a single-drive ptp link.  which works fine, since
> ide channels cost $15 or less, and ide disks are *so* much cheaper
> than scsi.

Yes. IDE as a PtP device works nice. But this means that in most cases
it is possible to connect only half of expected devices. What a pity :(


Best regards,


				Krzysztof Oldzki

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