[1768] in linux-scsi channel archive
Re: Mixing SCSI-2 (10Mbit) & Ultra-SCSI (20Mbit) on BT948
daemon@ATHENA.MIT.EDU (Agus Budy Wuysang)
Mon Apr 28 04:47:05 1997
Date: Mon, 28 Apr 1997 15:44:31 +0700
From: Agus Budy Wuysang <fswmis@rad.net.id>
To: "Leonard N. Zubkoff" <lnz@dandelion.com>
CC: baba@beckman.uiuc.edu, linux-scsi@vger.rutgers.edu
Leonard N. Zubkoff wrote:
>
>
> The 948 BIOS appears to know which devices support 20Mbit, but does having the
> 10Mbit devices there slow down the whole bus?
>
> Nope. Transfer period is negotiated separately with each target device.
> You should enable Ultra speed in AutoSCSI for only those devices that are known
> to be able to handle it, as some older Fast SCSI-2 devices fail badly when
> asked to negotiate Ultra SCSI (20.0 mega-transfer/second) speed.
How about transfer rate between 2 different SCSI device, eg Ultra
(20MHz)
to non-Ultra (10MHz)? Does the host adapter re-negotiate with the
ultra device down to 10MHz?
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