[1749] in linux-scsi channel archive
Re: Mixing SCSI-2 (10Mbit) & Ultra-SCSI (20Mbit) on BT948
daemon@ATHENA.MIT.EDU (Leonard N. Zubkoff)
Wed Apr 23 14:17:59 1997
Date: Wed, 23 Apr 1997 08:39:32 -0700
From: "Leonard N. Zubkoff" <lnz@dandelion.com>
To: baba@beckman.uiuc.edu
CC: linux-scsi@vger.rutgers.edu
In-reply-to: <199704222154.QAA07552@tigger.beckman.uiuc.edu> (message from
Baba Z Buehler on Tue, 22 Apr 1997 16:54:31 -0500)
From: Baba Z Buehler <baba@beckman.uiuc.edu>
Date: Tue, 22 Apr 1997 16:54:31 -0500
Does it matter if I mix 10Mbit SCSI-2 devices with 20Mbit SCSI-3/Ultra devices
on a BusLogic 948?
Not at all (it's megabyte/second, by the way).
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.
Leonard
