Akai S5000 Operator's Manual download pdf (Page 272)

262 Version 1.21

APPENDIX D /

CONNECTING THE SAMPLER TO A MAC/PC VIA SCSI

It is

theoretically

possible to connect your sampler to a Mac/PC and share the disk drive as follows:

However, great care must be taken because you can potentially damage your drive and lose data

irretrievably. As a result.....

THIS SETUP IS NOT RECOMMENDED.

The reason you may experience problems with this setup is because it is not good practice to have

two SCSI initiators on the same SCSI bus at the same time (an ‘initiator’ being a device with a CPU

- such as a Mac/PC or sampler - communicating with a SCSI peripheral). Furthermore, many SCSI

boards for Macs and PCs do not treat SCSI bus arbitration correctly (i.e. multiple initiators in a

system is not handled correctly). As a result, SCSI bus crashes can occur when a hard disk is

accessed by a sampler and a Mac/PC at the same time and depending on what the two devices

were doing at the time, this SCSI bus crash can corrupt a hard disk easily. SCSI was never designed

as a ‘networking’ system, just a means to connect a single initiator to SCSI peripherals such as

disk drives, CD-ROMs, etc. (for example, you would not network PCs or Macs together using

SCSI).

There are also other known problems when using a single disk shared by two SCSI initiators as

shown above. These are not unique to sharing an S5/6000 with a Mac/PC but can occur on

any

SCSI system that has two initiators (for example, two Mac/PCs sharing the same SCSI drive).

When a disk is ‘seen’ by a SCSI initiator, the disk’s directory is loaded into its RAM disk cache. The

directory (also referred to as the FAT or File Allocation Table) is where all the information about the

data stored on the disk is held. If the directory is damaged in even the slightest way, it is almost

impossible to access the data on the disk.

Under normal circumstances (i.e. a single initiator hooked up to one or more drives), any changes

you may make to data on that drive automatically update the directory in the initiator’s RAM so that

it knows about the changes and can deal with the data correctly. However, in the case where there

are two initiators sharing the same drive (as shown above), if changes are made to the disk by one

initiator, the other initiator’s directory cache is not updated and so it doesn’t have the latest and

current directory. And that’s where the problems start!

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Akai S5000 Operator's Manual Page 272