Re: What's the largest partition possible?

[foegelle@sleepy.cc.utexas.edu (Michael Foegelle)]

In article <1993Aug1.025947.9785@mnemosyne.cs.du.edu> jmaricon@nyx.cs.du.edu (Jim Maricondo) writes:
>ProDOS will only support partitions up to 32mb.  RamFast SCSI cards will only
>support 12 partitions. 

  I should qualify this by adding "AT A TIME!"  RamFAST will only let you have
twelve partitions online at once, but you can have more.  Prodos limits you
to fourteen drives anyway.  So with a RamFAST you can have a larger hard drive
but only access part of it without going back into RAMFAST.SYSTEM.  

Now I've come up with another option that works beautifully for my own 
applications.  It forces me to lose access to my 5.25" floppy drives when
the driver is loaded, but that's no loss anyway since my BBS has no use for 
the floppies.  What I did was to format my 330 meg drive but not partition
it.  The RamFAST will show it as a smartport device of the full size.  The
driver then 'soft' partitions it to look like a bunch of 32 meg partitions
and then you just select which partitions you want online at any one time. 
(Note:  Due to a bug in the RamFAST ROM's and the fact that HFS partitions
weren't supported before v3.0 of the ROM's, this won't work properly with
ROM's prior to version 3.0N.)  Under normal circumstances this isn't much
more useful than using the RamFAST itself since you still have to run a
program to switch partitions.  However for a custom program that can interface
to the driver and change the partitions automatically it works great.  This
technique could be improved by enlarging the driver and hooking into ProDOS
in a couple of places to intercept "VOLUME/FILE NOT FOUND" errors and put
an offline volume back online.  This would still be useless for 'drive only'
programs like Copy II+, but it would go far to solving the problem.  The soft
partitioned drive could be polled at bootup to find and save all of the 
volume names so that there is no need to read the drive to perform the
switch.  (Thus it could be 'switched in' before a 'FNF' error even occured.)

The other option of course is to upgrade ProDOS to support larger partitions.
In general that means redefining the Prodos file structure, not performing 
some sort of kludge like trying to support HFS.  The simplest fix would be 
to make a more advanced root directory structure.  Files and subdirectories
would still have to be limitted to 32 meg 'sections' of the drive, but the
root directory would have an extended file structure to direct to which 32
meg section.  As such, most file utilities would still operate correctly, but
block utilities would still probably choke.  A more preferable option might
be to at least just do away with slot-drive notation, or add more drives per
slot.  Most slot-drive software wouldn't work on those extra partitions, but
there are very few pieces of software that are so limitted.  And so what?  
They'd still work on the first 14 partitions and we'd still be able to go over
400 megs without too much trouble.  

(Granted, very few people will probably EVER put 500 megs on a //e, but it
was very disappointing/disconcerting to have bought another drive and discover
no way of accessing all of it.  Luckily I can program in assembly!) 

> Using Gs/OS you can format your drive using HFS for a max partition size of 
>a couple gigabytes..
>
> <<Jim
>--
>Jim Maricondo              | Apple II Forever
>DigiSoft Innovations       | Publishers of Twilight II, the ultimate screen
>___________________________|  saver for the Apple II!
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(P.S.  Use your return key dude!)

-- 
   Michael Foegelle  | Call Wunderland BBS! |   foegelle@ccwf.cc.utexas.edu
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