Subject: Re: sharing disks on the same bus with multiple hosts
To: Erik E. Fair <fair@NetBSD.org>
From: Bill Studenmund <wrstuden@netbsd.org>
List: tech-kern
Date: 04/09/2004 17:09:14
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On Fri, Apr 09, 2004 at 01:01:36PM -0800, Erik E. Fair wrote:
> NetBSD supports at least three busses that can have multiple hosts on=20
> them: SCSI, FireWire, and USB. Has anyone we know actually tried to=20
> share, say, a disk between multiple hosts on the same SCSI bus?=20
> Obviously for that case, some of the host SCSI IDs would have to be=20
> pre-set to something other than 7, and after that, there is a=20
> question of access arbitration and cache coherency...

The most-pressing kernel component is a way to tell a SCSI HBA to be at an=
=20
ID other than 7. While there are other additional components, they can=20
likely be handled in userland with some sort of failover software. Like=20
software to obtain and revoke reservations. In-kernel support'd be nice,=20
but the arbitrary SCSI command code will work for now.

Take care,

Bill

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