Multi boot with SCSI >1024 geometry This is serious stuff

Multi boot with SCSI >1024 geometry This is serious stuff

Post by Visi » Fri, 11 Apr 1997 04:00:00

Thanx in advance for taking time to acknowledge this post..

Normally I would assume that IDE and SCSI work the same, but thats
because I have always used DOS and never needed to really understand
drive geometry.  After Linux, I have learned quit a bit, accually A
LOT.  but theres still pieces missing from my puzzle I've done seaches
all over the place and cannot find any document that will put me that
one step up on my issue, (ahhhhh, I'm stuck on a plateu)  All the docs
are from ppl like me, (looking for help) and the other docs give the
basic idea and teach about large disk geometry, 80% of the ones out
there are the exact same document, at a different location.

Well, I've had this problem were I use a SCSI drive that has >1024
cyl. with total of 2GB, (and total of 2047 cyl.)  I though that this
was no problem with Linux, (now I think it does) and I know that DOS
doesn't lik it.  So what I tried to do was tell the AHA 2842
controller to change geometry (for the sake of M$-DOS) so that it will
also boot,  problem was I could get Linux to conform to this geometry,
I even tried to use the "apend hd=c,h,s" in LILO, with no success.
And I posted to a few different groups with no reply.

My solution to this was: forget about the translation, don't make DOS
1.5GB just leave it as 1GB.  so I didI told DOS to partition upto cyl,
1020, that worked fine.. Now it was time to have Linux installed on
the rest of the drive.  I started Linux at 1021 ..... NOW THIS IS WERE
THE PROBLEM COMES IN. I made that partition primary to finish at cyl.
1663. the next partition I made extended to complete the drive and so
that will start and finish at 1664 - 2047 respectively.  Inside this
ext part. I made a 16MB swap, and finished off the rest of the
ext.part. with a logical drive..

NOW, I hope you were able to follow me on that, If not Please e-mail
me and I'll send you the part.table that Linux generates.

(I'm not asking anyone to hold my hand here, just a point in another

I'm using a boot mngr from V-communication called system commander. (I
personaly give it and 11 on a 0-10 scale)

It recognized my DOS partition (no problem) it recognized my WIN95
partition (no problem) in recognized my Linux partition (with a
problem) it didn't boot it, as soon as I select Linux, it doesn't boot
it.. Now, I've had all three part. with successful boot when I was
testing. the only two difference were that all my partitions were
about 65MB therefore the last partition ended under cylinder 200.
and I didn't have any extended partition created..

So now I'm stuck BIG TIME.

I've tried my two theories and both have been unsuccessful.

they were (just to refresh) make Linux conform to the AHA >1G for DOS
translation. but Linux did not want to look at the "append" it gave me
and error with something like "hda cannot read 255 heads"  I noticed
two problems here the HDA which should show SDA (unless append is not
possible with SCSI) the the reason for the 255 heads is because DOS >
1GB is set to c=261,hd=255,sc=63 with out the translation its

and the other theory, was, don't use translation, and make sure that
all OS's start before c=1024.
that means 1 G for MS and 1G for Linux.

DIFFERENT GEOMETRY ON A SCSI DRIVE. ( if this is possible HOW, it
would solve all my problems.. I've been pulling my hair for about a
month now) is there a differnet switch for SCSI eg>apend sda=c,h,s ???

Or maybe I'll even settle for my second alternative and leave the
translation off, BUT does my ext part. have to start under 1024

And again, I'm not asking for someone to do it for me or to hold my
hand about this issue, I have been doing a lot of reading and testing,
but its pritty lame when this should only take a first timer a day or
two to figure things out.. I'm missing some piece of information
somewhere. Tips like would I be haveing the same problem if the drive
was IDE?? Is it possible to modify SCSI geometry??

I would really like to get out of this MS world,  But I can't just
jump out (it's too far, really though, I need things like 95 because
of the work I do)

I will be very greatful if you can e-mail me, also a post reply makes
no difference to me, I guess it would be better in case someone else
is haveing the same / similar problems..



Multi boot with SCSI >1024 geometry This is serious stuff

Post by Remco Blaakme » Sat, 12 Apr 1997 04:00:00

Quote:>1024 geometry This is serious stuff:

[long story about booting Linux from a 2047 cilinder disk]

Yes, Linux does support disks with >1024 cilinders. Problem is, Linux can
only support them after the kernel has been loaded. Before that, you have
to rely on the boot manager. All boot managers I know (I don't know System
Commander) simply use the drive geometry they get from the BIOS, so they
don't support large disks.

Now, you have a few options left that do work in this situation. Probably
the easiest of them is to use Loadlin to boot Linux. You can then add a menu
entry to your multi-config config.sys that loads Loadlin. To do this, add
a line
SHELL=<PATH>\LOADLIN.EXE <KERNEL-IMG> root=<Linux-partition> ro
to the section that is loaded when you select loadlin. If you don't
understand this, I can send you a sample config.sys by e-mail.

I haven't lost my mind -- it's backed up on tape somewhere.


Multi boot with SCSI >1024 geometry This is serious stuff

Post by Andries Brouw » Tue, 15 Apr 1997 04:00:00

...lots of problems...

Things are so simple.
Have you read the LargeDisk mini-HOWTO?

: Well, I've had this problem were I use a SCSI drive that has >1024
: cyl. with total of 2GB, (and total of 2047 cyl.)  I though that this
: was no problem with Linux, (now I think it does)

There is no problem with Linux.
And you are making another mistake: thinking that your SCSI disk
has a certain geometry with a certain number of cylinders - it hasn't.

(With IDE drives things are different: they are sometimes accessed
by the driver in C/H/S coordinates. SCSI drives are addressed by
logical block number - nobody cares whether the thing has any geometry,
and if so, whether the number of cylinders is larger than 1024.)

So, you only have to make sure of two things:
(i) that you can boot: At boot time there is no Linux yet, so
the boot loader must use BIOS or private code to find your system.
(ii) that the various systems have the same ideas about the `geometry'
so that DOS will not scribble on a Linux partition.

Concerning (i): usually, adding the keyword `linear' to the LILO
config file suffices. In emergency cases you can also use loadlin,
or any other boot loader.
Concerning (ii), read the HOWTO mentioned above.
The boot options you have depend on the SCSI controller.
Probably the BootPrompt HOWTO also has some info.
Usually doing nothing is the right answer.


Multi boot with SCSI >1024 geometry This is serious stuff

Post by Stephan Pt » Wed, 16 Apr 1997 04:00:00

...lots of unread things!

This is what S.u.S.E. tells to solve your Problem
(somewhere on

Just mount a (quite small) partition at the begin of your disk (<1024)as /boot
and put the kernel into /boot. The rest of your filesystem should be in
another partition (especially /). Install Lilo into the MBR and everything
works fine.
The first ~500 MB of your disk can be used by other OS, e.g. DOS or win.
Since Linux does not use the bios, linux can access all parts of the disk.
Only lilo needs to use the bios routines to load the kernel.

Viele Gruesse