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From: jesup@cbmvax.commodore.com (Randell Jesup)
Newsgroups: comp.sys.amiga.hardware
Subject: Re: Who's got the biggest SCSI drive actually functioning
Message-ID: <13191@cbmvax.commodore.com>
Date: 12 Jul 90 22:31:37 GMT
References: <1990Jul4.035345.18031@zorch.SF-Bay.ORG> <31485@cup.portal.com>
Reply-To: jesup@cbmvax (Randell Jesup)
Organization: Commodore, West Chester, PA
Lines: 60

In article <31485@cup.portal.com> thad@cup.portal.com (Thad P Floryan) writes:
>Perhaps.  Considering the problems with which I helped Dale Luck attempt to
>setup a Maxtor XT3380 on an A2090 on one of his A2000, we never got it to
>work.  The same drives work fine on my setup.  (Dale's problem was about 18
>months ago, and perhaps it's been fixed since, but I don't know.)

	2090's have problems with certain things, such as very large drives and
drives with very large tracks ( >127 sectors I think ).  The A2091 is _far_
better, as is the setup and partitioning software.

>	3) Are there limitations in AmigaDOS or in the SCSI standard that
>	   force large disks to be partitioned in multiple pieces, or can
>	   I just make it one huge tree?

	OFS (in 1.3 and before) was limited to ~50 megabytes.  FFS isn't
limited, though there were some pre-release versions with ~350 MB limits.
I think those were fixed for 1.3 release, certainly for 1.3.2.  The limit 
for FFS is the limit imposed by drivers, of 4GB per drive.  Also,  Read()
and Write() are limited to 2GB (negative returns are errors).

>	4) If I can make it one big partition, are there good reasons for
>	   making it several smaller ones instead?
>
>Considering the difficulty getting tape drives working for ALL Amiga setups,
>my advice re: partitioning is to partition ONLY if you cannot afford to nurse
>an all-files backup in one sitting.  The last all-files backup on one of my
>Amigas required 1,604 floppies using Quarterback.  I'm testing some tape
>software on and off recently and have 5 different tape drives being tested.
>Seems the problem(s) center(s) around SCSI-direct commands.

	Hopefully that should end now that there's a standard piece of
Commodore software that uses SCSIDirect (HDBackup/bru on 2.0).  We all have 
SCSI tape drives here at Commodore-Amiga attached to our A2091's/A3000's.

	Personally, I partition into chunks to a) make backup easy, b)
provide "firewalls" against a trashed partition (remember I run test versions
fairly often), c) reduce fragmentation (separate things that change a lot
from those that don't, etc.  I also make the partitions the same size, so
I can use one partition as a "hot backup" using diskcopy, for daily backups
of important source.

>Kinda weird how SCSI has come so late to the ``PC'' marketplace yet the
>overall SCSI support is so much better for the ``PC'' than for other systems.
>Some of the freely-redistributable software from one of Adaptec's field
>service persons in Texas even allows one to alter the SCSI OS in SCSI devices.
>Great stuff!  Now WHY isn't such good software available for the Amiga? 

	SCSI support good in the PC market???  Read some of the things
that go on there.  Most devices require their own controller per device (no
scsidirect there).  It's hard to plug-and-play with drives, etc, etc.
With SCSIDirect, it's trivial to write a scsi-toy program that allows playing
and looking around all the stuff in a scsi device, and it should work with
all Amiga SCSI controllers, whereas for the PC market you'd have to write that
program very low-level (bit-banging), and redo it for each controller.
Try reading comp.periphs.scsi.

-- 
Randell Jesup, Keeper of AmigaDos, Commodore Engineering.
{uunet|rutgers}!cbmvax!jesup, jesup@cbmvax.cbm.commodore.com  BIX: rjesup  
Common phrase heard at Amiga Devcon '89: "It's in there!"