Re: SCSI and...How many?

[dempson@actrix.gen.nz (David Empson)]

Supertimer <supertimer@aol.com> wrote:

> pilgrim <barpri@teleport.com> wrote:
> 
> >Question: I have a GS ROM 3 that has a Focus drive AND a CMS SCSI on it.
> >the  SCSI has 3 Hard Drives 1 of which has 2 partions.  Adding in
> >networked drives  from 2 Macs, plus my 5.25 and  2 loaded 3.5 drives and I
> >have had a total of  23 disks showing on the desktop. If I drop
> >into ProDOS 8,  all the  higher ones disapear, but in GS they are there.
> >What is the limit in GS  or, is there one?
> 
> 14 volumes (including /RAM in slot 3, drive 2) for ProDOS 8.

You might not be able to use all 14, however.

If you have a RamFast SCSI card, I believe it can remap partitions as
you see fit.

With an Apple SCSI card (or any other disk controller card which
supports the SmartPort firmware interface), you need ProDOS-8 2.0.1 or
later, which automatically remaps additional SmartPort volumes to unused
unit numbers.  Disk ][ or UniDisk 5.25 controllers are always treated as
having two drives connected, so you might end up wasting a unit number
if you only have a single 5.25" drive.

With ProDOS-8 1.9 and earlier, you get two units per slot, with a
special case (supported by ProDOS-8 1.2 and later) for slot 5, where a
third and fourth device can be remapped to slot 2, provided there is no
disk controller card in slot 2.

> For GS/OS, I think the limit is 64.

There is a hard limit of 63 volumes per driver (e.g. 63 SCSI partitions
spread over all drives and multiple Apple SCSI cards).  I've never heard
of a limit on the total number of volumes in the system - it is probably
only limited by available memory.

If you imagine a system which had a Focus, RamFast _and_ Apple SCSI
card, and a lot of drives connected to both the SCSI cards, you could
get lots of partitions on the Focus, plus 63 on the RamFast, plus 63 on
the Apple card (plus any 5.25", 3.5" and RAM5, assuming you had enough
slots).

Individual applications (including Finder) may have problems if you have
an excessive number of volumes online.

-- 
David Empson
dempson@actrix.gen.nz
Snail mail: P O Box 27-103, Wellington, New Zealand