Re: IDE hardrive limitations

[Nick Holland <nhollan@home.com>]

Well, I haven't seen any firm, all encompassing answer to the limits of the OpenBSD huge IDE
support from anyone yet, so I'll throw out my experience and testing

Because I hadn't played with a >8G IDE drives, I went out and bought a 40G Maxtor IDE drive last
week, for the purpose of trying out what happens with different OSs.  I figure soon, I won't be
able to easily and rapidly get "small" drives for emergency replacments for my clients when they
break, so I figured I had better find out what supports what under what circumstances.

So far, what I have done:  The machine I am currently fiddling with is a Dell Pentium 75.  The BIOS
supports drives bigger than 504M, but appears to choke past 2G (by experimentation: The machine
recognized a 400M and a 1.2G fine, but refused to boot on a 3.1G or the 40G).  To get the machine
to accept the 40G HD, I turned off the BIOS autodetect and manually set the drive type to
1024cy/16hd/63spt (504M).  At this point, I was able to successfully install and boot OpenBSD.

Not that I didn't have some minor and bizzare problems.  This note was going to be saying "it
didn't work".  Due to a hardware problem on this particular machine, the second IDE port is broke
(to everything -- inc. DOS), so I attached the (not really new, but not horribly old, either) IDE
CD-ROM as a slave on the primary channel.  OpenBSD would NOT recognize the 40G drive this way.  I
found DOS and Netware 4.1 and 5.0 recognized the drive and the CD-ROM (in case anyone cares,
unpatched 4.1 saw the drive as an 8G.  Netware 5.0 unpatched saw the whole drive.  VERY incomplete
testing, obviously -- I want to find out what will happen with patched Netware 4.1, 4.11, and 3.12,
but I digresss 8-), so things CAN work, they just didn't with OpenBSD.  As I started this note, I
remembered that I should remove the CD-ROM before I say it doesn't work, and by golly, it DID work
GREAT!

On another similar environment, I found I had trouble getting OpenBSD to co-exist on a large drive
with a DOS partition on a BIOS which didn't support the big drive.  In this case, it was an IBM
PS/1 486 with a BIOS limit of 504M.  OpenBSD recognized and worked fine with a 4G IDE drive, but I
couldn't keep get it to work with a small (~100M) DOS partition still on the disk, I had to answer
"Y" to the question about using the entire disk for OpenBSD to get it to work.  NB: This may be my
problem more than OpenBSD's problem (i.e., I may not have known the trick), but I have successfully
kept DOS partitions on other OpenBSD systems, so I kinda know my way around the partitioning and
disk slice programs (the proper names of which are slipping my mind at the moment, and considering
the number of times I've run up and down the basement stairs to write this message, TOUGH! 8-).

The IBM PS/1 with the 4G IDE, I had a chance to test pretty completely, including filling the drive
up with big files, over a number of weeks.  The 40G on the new drive, as I said, I just realized
how to "fix" the problem, I haven't had a chance to really test it as I would like to before I
swear it is a good system.  I'd also love to hear from someone who can say with authority "Oh, it
works great", or "Here is a problem to check for before declairing success" for all I can relate is
my tests and my results.

I must say, I am impressed by OpenBSD's ability to work with HUGE hard disks (five years from now,
I know we will get a laugh over my calling a 40G drive "HUGE" 8) even on computers which thought a
504M or a 2G drive was as big as we would ever need.

I want to do more testing yet, including mounting the 40G on a very old 486 (504M limted BIOS) and
see what happens.  I got this drive for experimentation, so if anyone has any suggested tests, let
me know (off-group if not OpenBSD related)

Nick.

LiNT ___ wrote:

> I think I remember seeing something regarding this awhile ago, but I can't seem to find it now.
>
> Does OpenBSD support IDE harddrives over 8GB.?The bios recognizes it if that matters.
>
> Thanks,
> Jim
>
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