Multiple compacts on one hard drive

[Quadraman]

Can you connect more than one compact to a single external drive?

 

[tmtomh]

Not at the same time. Each compact's motherboard will have the same SCSI ID, which - combined with the fact that both computers will at some point be trying to read and/or write from the drive at the same time - will corrupt the data on the HD, potentially corrupt the internal HDs of the compacts, and crash both computers.

M

 

[Aoresteen]

The only way to do it is to set up a shared drive over a network. It will physically be attached to a single Mac but the drive will apear on the other Macs desktops.

 

[Anonymous Freak]

It is theoretically possible to have multiple computers connected to a single SCSI device, but the computers AND the device all need to be aware of the multiple computers. (This also carries over to FireWire.)

As far as I know, no 'conventional' hard drives support multiple computers at the same time. Some ultra-high-end server drives did, but they required that the SCSI cards in all connected computers support it, too. This role has been effectively replaced with FibreChannel, which can do it through the use of a FibreChannel switch.

 

[trag]

You could do this with the Outbound Model 125 Laptop and the external SCSI Adapter.

The Outbound Model 125 allowed one to set the SCSI ID of the host (the Laptop) so that one could do the docked thing, i.e. attach the Laptop as an external SCSI drive to another Macintosh. However, if you exited the pretend-you're-a-hard-drive mode and booted normally, the Outbound would have access to all the SCSI devices on the chain at the same time as the host Macintosh.

I did this trick with my IIci and my Laptop Model 125 several times. That way you can give the Outbound access to the internal drive of the IIci.

Since SCSI Powerbooks also had this ability (I understand that Apple licensed it from Outbound) it might be doable with PowerBooks as well.

 

[LCGuy]

Be careful - A few years ago, I once blew out a SCSI chip by doing this.

I didn't actually blow it, per se, but afterwards, the Mac wouldn't recognise ANY SCSI device connected to it.

 

[tomlee59]

Be careful - A few years ago, I once blew out a SCSI chip by doing this.
I didn't actually blow it, per se, but afterwards, the Mac wouldn't recognise ANY SCSI device connected to it.

Actually, that's pretty much the definition of "to blow out."

 

[LCGuy]

Lol, what I meant was that, well, the chip didn't actually physically blow.

 

[Bunsen]

You used to be able to do this with Ensoniq samplers and a Mac, sharing one external HD. The sampler had a different SCSI ID than the Mac.

 

[TylerEss]

The big issue is just to make sure you don't both try to write to the same file at the same time, right?

 

[Aoresteen]

This role has been effectively replaced with FibreChannel, which can do it through the use of a FibreChannel switch.

Humm. The cost of say 3 4 gig SCSI drives vs a FiberChannel switch?

I couldn't justify the cost of a Fiber Channel environment for work. They ain't cheap! Just buy individual SCSI dreives for each machine and hook up AppleTalk.

 

[Charlieman]

From my personal notes:

ProApp 20

The unusual ProApp 20 drive is an external device with both SCSI and floppy port connectors. Macs can connect to the drive via either port and Apple II computers can use the floppy port (the ProApp predates the availability of Apple II SCSI controllers). An external power supply is used.

Software supplied with the drive can partition the disk in separate volumes for the Mac and Apple II. It is also possible to connect a Mac and an Apple II to the disk simultaneously, but an I/O error occurs if both try to access the disk at the same time, limiting the use of this feature. If used with a Mac on its own, the disk can be formatted using a standard SCSI formatter. The drive cannot be included in a SCSI chain (ie it must be the only SCSI device attached to the Mac).