1023 Cylinder Limit
Steve Morris
Well, what a fiasco!
finally got my hands on the latest "allsinging, all dancing" SCO OpenServer
5.0.5 Enterprise. Started my installation with eager anticipation.
Everything goes through fine - no problems.
Go to restart and I get the terse error message "CYL OVF".
This apparently relates to an old limitation that I was aware of years ago
with regard to the root filesystem having to reside with the first 1023
cylinders of your hard disk.
However, I had thought that by the release of 5.0.5 that this would've been
a thing of the past. I have a 9.1Gb disk which is partitioned into C,D,E & F
which are all FAT 16 and of 2Gb each. My plan was to install 5.0.5 into the
last 600Mb or so.
What annoys me is that at no time during installation did SCO inform me that
I was installing the root filesystem above this cylinder limit. Surely the
installation routines are smart enought to realize what region of the disk
you're installing into?
Anyway, I have 2 questions'
1. Is there any way around this problem?
2. How can I determine how many cylinders my SCSI HD has? (Looking at
manufacturers web sites doesn't have this info).
HELP!
--
Regards
Steve
Tony Lawrence
> This apparently relates to an old limitation that I was aware of years ago
> with regard to the root filesystem having to reside with the first 1023
> cylinders of your hard disk.
>
> However, I had thought that by the release of 5.0.5 that this would've been
> a thing of the past.
It's nothing to do with OSR5. That's a BIOS limitation,
period. In other words, the hardware is at fault, not SCO.
--
Tony Lawrence (to...@aplawrence.com)
SCO/Linux articles, help, book reviews, tests,
job listings and more : http://www.pcunix.com
Steve Morris
Looking at Adaptecs UNIX Q & A web page, they say that cylinder 1023 falls
withing the first 1Gb of disk space. If this is the case, then I am going to
have to re-install all my Windows stuff again.
Does this sound right to you - do you have any suggestions?
Thank you.
--
Regards
Steve
"Tony Lawrence" <to...@aplawrence.com> wrote in message
news:38A6AF47...@aplawrence.com...
--
Regards
Steve
"Tony Lawrence" <to...@aplawrence.com> wrote in message
news:38A6AF47...@aplawrence.com...
Ken Wolff
degree. You may want to look into that, but make sure you've got a good
backup before attempting it.
--------------------------------------------------------------
Ken Wolff
Phone: 616-957-4949 Ext: 111
FAX: 616-957-1614
--------------------------------------------------------------
Stephen M. Dunn
$Go to restart and I get the terse error message "CYL OVF".
$
$This apparently relates to an old limitation that I was aware of years ago
$with regard to the root filesystem having to reside with the first 1023
$cylinders of your hard disk.
Since then, it's changed; SCO Unix now uses a separate boot
filesystem, so that you don't have to fit the whole root filesystem
under the 1024-cylinder limit. But the general idea is the same:
you have to fit _something_ within those first 1024 cylinders.
$However, I had thought that by the release of 5.0.5 that this would've been
$a thing of the past.
Don't blame SCO; they had nothing to do with the design of the
BIOS on your system.
The problem here is that the standard BIOS calls use a 10-bit
quantity to represent the cylinder number, and that means cylinder
numbers can only be from 0 to 1023, inclusive. Once you've loaded
the Unix kernel and it's running, it uses its own disk drivers,
which are not limited to what the BIOS sees, but until that
point, you have to use the BIOS calls, which means you're limited
to the first 1024 cylinders of the drive.
$1. Is there any way around this problem?
Your boot filesystem defaults to 20 MB. This, plus a little
bit of stuff that comes before it (divvy table, boot loader, etc.),
need to reside in the first 1024 cylinders, so you'll need slightly
more than 20 MB free there. The rest can follow from cylinders
1024 onwards without problems.
$2. How can I determine how many cylinders my SCSI HD has? (Looking at
$manufacturers web sites doesn't have this info).
It's not actually how many physical cylinders the hard drive has,
but rather how many logical cylinders the host adapter says it has,
which will be a different number. Between the hard drive and the
host adapter, there are no cylinders, heads, or sectors; there is
simply a series of numbered blocks. However, to make this look
more like a hard drive, the host adapter maps it into cylinders,
heads, and sectors; that way, standard BIOS calls will work.
Exactly how this mapping is done varies from one host adapter
to another, and there may be host adapter settings that influence
it, too.
During installation of Unix, it may print a line on the console
listing the geometry that the host adapter is presenting. My
system has an ATA hard drive, so the line won't look exactly
the same, but here are the lines printed for my two hard drives:
%disk 0x01F0-0x01F7 14 - type=W0 unit=0 cyls=1025 hds=255 secs=63
%disk 0x0170-0x0177 15 - type=W1 unit=1 cyls=944 hds=14 secs=40
Yours will look close enough that you can recognize them.
Failing that, check the documentation for your host adapter.
--
Stephen M. Dunn (SD313), CNE, ACE ste...@bokonon.ussinc.com
----------------------------------------------------------------------------
Senior Manager United System Solutions Inc.
104 Carnforth Road, Toronto, ON, Canada M4A 2K7 (416) 750-7946 x251
Dan Buckler
know. The root of the problem is the CHS addressing scheme
(Cylinder - Head - Sector). The problem is that the number of bits
need to represent the number of Cylinders exceeds the number of
bits set aside for this purpose in the bios. To overcome this problem
the ATA hardware vendors introduced LBA (Logical Block Addessing)
To make SCO work 5.0.5 work is not very hard actually. Try this:
1) find out the number of cylinder, heads and sectors from reading the
top of the drive, or from the drive vendors web site.
2) Do this at boot prompt: (substiture the values you found)
boot
: defbootstr biosgeom=(#cyl, #heads, #sectors)
- Dan
On Sun, 13 Feb 2000 19:39:07 -0800, "Steve Morris"
<Stephen...@btinternet.com> wrote:
>Thanks for claryfying this for me.
>
>Looking at Adaptecs UNIX Q & A web page, they say that cylinder 1023 falls
>withing the first 1Gb of disk space. If this is the case, then I am going to
>have to re-install all my Windows stuff again.
>
>Does this sound right to you - do you have any suggestions?
>
>Thank you.
>
>--
>Regards
>
>Steve
>"Tony Lawrence" <to...@aplawrence.com> wrote in message
>news:38A6AF47...@aplawrence.com...
>> Steve Morris wrote:
>>
>> > This apparently relates to an old limitation that I was aware of years
>ago
>> > with regard to the root filesystem having to reside with the first 1023
>> > cylinders of your hard disk.
>> >
>> > However, I had thought that by the release of 5.0.5 that this would've
>been
>> > a thing of the past.
>>
>> It's nothing to do with OSR5. That's a BIOS limitation,
>> period. In other words, the hardware is at fault, not SCO.
>>
>> --
>> Tony Lawrence (to...@aplawrence.com)
>> SCO/Linux articles, help, book reviews, tests,
>> job listings and more : http://www.pcunix.com
>>
>
>--
>Regards
>
>Steve
>"Tony Lawrence" <to...@aplawrence.com> wrote in message
>news:38A6AF47...@aplawrence.com...
>> Steve Morris wrote:
>>
>> > This apparently relates to an old limitation that I was aware of years
>ago
>> > with regard to the root filesystem having to reside with the first 1023
>> > cylinders of your hard disk.
>> >
>> > However, I had thought that by the release of 5.0.5 that this would've
>been