Re: SCSI Hard Disk Limitations

["Bryan Parkoff" <BParkoff@satx.rr.com>]

    Is it true that HFS has a lot of wasting space or clusters if beyond
512MB to 2GB?  Curious...

--
Yours Truly,

Bryan Parkoff
BParkoff@satx.rr.com
"David Empson" <dempson@actrix.gen.nz> wrote in message
1fnemk6.179hiho1sbxaf4N%dempson@actrix.gen.nz">news:1fnemk6.179hiho1sbxaf4N%dempson@actrix.gen.nz...
> Paul H. Lee <earnhardtfanpl@hotmail.com> wrote:
>
> > I have an Apple SCSI Card, REV 'C' installed in my ][gs with a ROM 01
> > motherboard.  The machine has a ZipGSX and 6 megs of RAM.  What is the
> > largets SCSI hard disk I can use?  I connected a 250Mb hard disk to
> > the system, and everything works fine; but when I connected a 2Gig
> > drive, the system did not even see it.
>
> You might be running into a limitation of the firmware in the SCSI card,
> but it is more likely to be some other kind of compatibility issue with
> that particular drive, or something like the new drive not supplying
> termination power while the old drive did.
>
> The absolute limit for ProDOS-8 with the original Apple SCSI card is 7
> partitions of 32 MB each, for a grand total of 224 MB usable space.  A
> larger drive will work, but extra space will be inaccessible.
>
> Under GS/OS, there is a theoretical limit of 63 partitions, and you can
> have a mixture of HFS and ProDOS partitions.  HFS partitions can be up
> to 2 GB (though they have rather a lot of wasted space if larger than
> 512 MB), ProDOS partitions are limited to 32 MB.
>
> In principle, a SCSI card should be able to support 48-bit block numbers
> (128 EB), which is the limit of the SCSI command set.  There may be an
> implementation limit in the firmware of the Apple II SCSI cards so that
> they can only handle 32-bit block numbers, which would limit the drive
> to 2 TB.
>
> An artificial limit of 2 GB would mean that it is only using a 22 bit
> block number, which would be a rather strange limit.  (4 GB or 8 GB
> seems more likely.)
>
> --
> David Empson
> dempson@actrix.gen.nz