From: badboy@netcom.com (Jay Keller)
Newsgroups: comp.os.os2.misc
Subject: Re: 2.0 questions ...
Date: 16 Apr 92 07:52:25 GMT
Article-I.D.: netcom.7vzjk-h.badboy
Organization: Netcom - Online Communication Services  (408 241-9760 guest)

In article <1992Apr8.220652.12206@cs.joensuu.fi> jhakuli@cs.joensuu.fi 
(Janne Hakulinen) writes:

>
>    1) With MOST can I direct dos system to physically
>       different drive ?

I've been meaning to write down my conclusions after playing with OS/2 2.0
hard disk arrangements for a while, this is a good time...

There are a lot of factors which make it challenging to plan the best way to
partition a hard disk or disks for OS/2 2.0.   MOST (Multiple Operating System
Tool) and the HPFS/FAT considerations yield a lot of possibilities for many
systems.

I'm not an "authority" but I have installed a few dozen 2.0 systems with
widely varying configurations, and the following is based on what I've 
learned, sometimes the hard way.  If any inaccuracies exist, I apologize and
I would wish to be informed.  MOST changed a lot during the EEP, but the GA
version seems to be much the same as the 6.304 beta, as far as I can tell
so far.

Some "considerations":
 
A bootable DOS partition must reside on a primary partition on the first
physical drive.
 
With MOST, you can select between multiple primary partitions at boot time.
Only one primary partition per physical drive will be accessible at any one
time.  The maximum number of primary partitions per physical drive is 4.  I'm
not sure if MOST itself counts as one of these, does anyone know?

MOST takes 1 meg (can be undesirable on small systems already disk-bound).

OS/2 can boot from a logical drive in an extended partition if and only 
if the Boot Manager (MOST) is installed.

With 2 physical disks, the primaries on the first physical disk will share the
C: designation, and if there are any primaries on the second physical disk
they'll share the D: designation.  Then E:, F:, etc. will apply to the rest of
any logical drives on the first physical and then on the second physical.
This can be confusing.  Consider that a system with two physical disks each
with one primary and 3 logicals will have C: E: F: on the first physical
drive and D: G: H: on the second.

The plot thickens a lot when we add the DOS considerations.  

If any HPFS formatted drives exist, they and any drives (HPFS or FAT) which 
come after them on the same physical disk cease to exist when DOS is booted
(either from a floppy or harddisk).  So for example if the system described
above had C: E: F: on the first drive and D: G: H: on the second, and let's
say E: (or E: and F:) are formatted HPFS.  Then if DOS is booted the first
physical drive contains C: (same C: as before) and the second physical disk
now has D: E: F:.  This can cause havoc, as some of the drives have been
re-designated.

A partition which can boot DOS (formatted FAT, of course) and which is large
enough to hold OS/2 can be set up as a "Dual-Boot" partition.  For many users,
this may be perfect and there would be no need for MOST.  Dual-boot precludes
the use of HPFS for the boot drive, but one or more HPFS drives may exist,
DOS won't see them.

Dual-Boot must be planned before OS/2 installation, as the DOS system must
be installed first, and must be slightly modified.   OS/2 installation will
then automatically set up Dual-Boot, as long as it is installed to the DOS
boot drive and the drive is not re-formatted during OS/2 installation.

The most important thing to advise new OS/2 2.0 users is to partition the
hard disk.  Do not install OS/2 2.0 into a single large disk which holds
all the systems data and applications.  The system is infinitely more 
maintainable if the disk is partitioned so that the OS is isolated in its
own partition with sufficient space to hold it.  The swap file may reside
in this partition with the OS, or it may be given it's own logical drive
to prevent fragmentation.  Don't make the boot drive too small as the OS
can grow well above the installed size, as fonts and device drivers are
added.  The print spooler needs disk space also, if large files are to
be printed.  And creating more complicated Workplace Shell environments makes
the disk requirements grow also.  I'd say give it a minimum of 40 meg if
the swapper is pointed elsewhere or maybe 45 or 50 if the swapper stays on the
OS/2 boot drive.  60 megs wouldn't be too much if it can be spared.

Regards,

Jay Keller
ROLM Systems
Santa Clara, California, USA

badboy@netcom.com

The opinions expressed are my own and don't necessarily reflect those of my
employer.