[SunHELP] One tape unit for 2 machine.

[Brian Dunbar]

On Feb 11, 2004, at 12:12 PM, Phil Stracchino wrote:

> On Wed, Feb 11, 2004 at 03:35:01PM -0200, Joaquim Humberto Marques 
> Mota wrote:
>> Hi
>>
>> We have one external tape unit (DDS4) with two scsi interaces 
>> (In/Out).
>>
>> I4d like to share this unit between 2 machines (SF 280R e E3500). Each
>> one connected on SCSI interface of tape unit.
>>
>> How to modify a SCSI ID of port in a Sun Fire 280R to avoid problems
>> with host signalling?
>
> Uh, wait a minute, you want to connect a single SCSI device to two host
> controllers in two different machines?!?
>
> Be afraid.  Be very afraid.  That tape drive, contrary to your belief,
> does NOT has two SCSI interfaces.  It has one interface.  There just
> happen to be two ports on that one interfact, two connectors which are
> *directly connected* electrically to each other and the drive's
> controller, to permit daisychaining.  If you try to connect this to two
> different SCSI controllers simultaneously, the results will be very 
> bad.
> Devices do exist which are designed to be connected to multiple hosts 
> at
> once; your DDS4 drive is not one of them.
>
>
> Install software that will share the drive's services.  Do not try to
> physically share the drive.

This was a few years back, but for years we shared a single tape drive 
on a central file server among workstations via NFS mount - between 1-4 
workstations and/or servers backed up to the single drive.  This worked 
well for the branch offices which had at most 20 staff.