RLL controllers & 386/ix

[Piercarlo Grandi]

In article <1989Aug29.162452.10538 at agate.uucp> ilan343 at violet.berkeley.edu writes:

   >I am setting up a 386 clone that will eventually run a version of UNIX,
   >probably 386/ix. Since I am trying to keep costs down, I am thinking of
   >using a large (120MB) RLL hard-drive.  I see from Interactive's list of
   >compatible hardware that they limit the choices of RLL controllers,
   >which concerns me a bit.
   >Can anyone report their experience (good or bad) trying to install
   >versions UNIX/386 in systems with RLL controllers?

I am using an ACB 2372B on my 386 with ESIX 3.2; it works fine. It is
quite fast, and does have a read ahead cache (small), which helps a little
bit. It does support 1:1 low level format. The ESIX disc driver is
not a speed monster unfortunately.

In article <2237 at infmx.UUCP> aland at infmx.UUCP (Dr. Scump) writes:

   No personal experience here; just some vendor info.  ISC claims
   compatibility with just 4 RLL controllers (Adaptec ACB-237[02],
   Bell Tech [Intel?] B-130, and WD 1006V-SRZ).  ESIX, on the other
   hand, specifically disclaims RLL support in the literature I received
   just yesterday.

This is bizarre, because the ACB 2372 is virtually register level
compatible with the standard MFM controller, the WD1003. The disc
driver does not even realize that it is an RLL controller. The
only difference is that RLL drives that have 26 sectors/track,
not 17; but the driver can be configured to cope with that (in
/etc/partitions).

As I said, it does work on my machine. There is one problem with
ESIX: if your disc geometry does not appear in the ROM table, you
are more or less stuck if you use the standard installation
procedure. Unfortunately most ROM tables do not have entries with
26 sectors/track. Thank goodness you can make your system work
nonetheless.  Just write manually an /etc/partitions file,
instead of letting disksetup build it, taking care of specifying
the right geometry.

UNIX itself never looks at the ROM tables; they are only read
during boot (and then you only want to make sure that the drive
type you assigned with setup is for an entry with the right
number of heads; cylinders and sectors are not important), and
during installation, as disksetup consults the ROM table to get the
geometry info to put in /etc/partitions. If you do that yourself,
all is ok.

I think that a good bet for a disc to use with an ACB 2372 is either an
ST4144 or a Miniscribe 3128 (but most probably a 3085 will work); both will
give you 110-20 Mbytes of clean disk. Buy two, and your machine will be very
fast. Price for either, thru mail order, is around $560-$570 (that is,
two RLL'ed discs will give you 220 Mbytes, and are much faster for multiuser,
than the otherwise excellent miniscribe ESDI 150 MBytes disc, even if this
has 17ms average seek).

My own preference goes to the Miniscribe; it has 22ms average seek, and is
*half height* (the seagate is 28ms average seek, is full height, and many
have had bad experience with seagate drives and constantly-seeking Unixes).
-- 
Piercarlo "Peter" Grandi           | ARPA: pcg%cs.aber.ac.uk at nsfnet-relay.ac.uk
Dept of CS, UCW Aberystwyth        | UUCP: ...!mcvax!ukc!aber-cs!pcg
Penglais, Aberystwyth SY23 3BZ, UK | INET: pcg at cs.aber.ac.uk