[328] in linux-scsi channel archive
BT-946C, MIC-3243, disk geometry and booting
daemon@ATHENA.MIT.EDU (J.H.N.Chin@reading.ac.uk)
Sat Jul 8 01:08:04 1995
From: J.H.N.Chin@reading.ac.uk
Date: Fri, 7 Jul 1995 18:36:33 +0100
To: linux-scsi@vger.rutgers.edu
First a thank you to everyone who answered my previous question about
PCI SCSI controllers. I have ended up getting a buslogic BT-946C
controller and a Micropolis 3243 4GB drive. After a little fiddling
with IRQs on the motherboard, it seems to be working happily although
the machine locks up under DOS when I try to use the BTFDISK utility.
Now I have a question about disk geometry.
When I run fdisk ("v1.5b" or "v2.0d (>2GB)") on the drive, I get:
Gilgamesh:~# fdisk /dev/sdb
You must set heads.
You can do this from the extra functions menu.
Command (m for help):
The latest sun format.dat file that I found on the sun-manager's archive
gives:
disk_type = "MICROPOLIS 3243-19" \
: ctlr = MD21 : fmt_time = 9 \
: ncyl = 4139 : acyl = 2 : pcyl = 4141 \
: nhead = 19 : nsect = 106 : rpm = 7200 : bpt = 63282
from which I infer that I should set:
heads = 19
cylinders = 4141 (4139 ?)
sectors = 106
fdisk only allows sectors to go up to 63 so I have used:
heads = 19
cylinders = 8282
sectors = 53
Is this okay? I know the README says it isn't wanting the real
cylinders, etc, (which is just as well since the spec says it
has 3659 cylinders) but would be interested to know the
significance of various choices for numbers.
For 200MB/100MB/1600MB/2GB partitions, I get:
Command (m for help): p
Disk /dev/sdb: 19 heads, 53 sectors, 8282 cylinders
Units = cylinders of 1007 * 512 bytes
Device Boot Begin Start End Blocks Id System
/dev/sdb1 * 1 1 407 204898 83 Linux native
/dev/sdb2 408 408 611 102714 82 Linux swap
/dev/sdb3 612 612 3866 1638892+ 83 Linux native
/dev/sdb4 3072 3867 8282 2223456 83 Linux native
Command (m for help): v
Warning: partition 3 overlaps partition 4.
51 unallocated sectors
I guess I don't need to worry about the "overlap" but I would be
interested to know what it means. I am confused that the "begin"
seems to have moved from what it was originally (but I'm not sure).
Should I be concerned by the 51 unallocated sectors?
Is there another way to partition the disk to avoid it?
Once I've fed the geometry info to lilo, will it be able to boot
from anywhere on disk (if I made it into one big partition say)
or does this `1G BIOS limit', or whatever it is, still apply?
The other question (sorry if it's not strictly linux-related):
On the system I have an IDE drive, a SCSI disk (id 0) and the
micropolis (id 1). The current setup has / and swap (and a dos
partition) on the IDE and /usr and /home on the SCSI disk. I am
hoping to move all the linux stuff to the micropolis so that I can
remove the IDE and smaller SCSI disk to another machine should that
become desirable.
Is there a way for me to boot off the micropolis without (as my
reading implies I must) detaching the IDE drive?
Will it be enough to give the micropolis a lower id and make
the IDE drive unbootable (no active partitions) so that the boot
uses the `int19h' stuff that the buslogic setup talks about?
The idea is to have all the `controls' (ie. lilo) on the micropolis
so that the other drives can be removed if/when I feel like it,
without having to fiddle with the setup.
thank you,
-jonathan
--
Jonathan H N Chin, 3 kyu | Cybernetics / CompSci | "Respondeo, etsi mutabor"
| University of Reading |
shrchin@reading.ac.uk | Reading, RG6 6AY, UK | < Rosenstock-Huessy >
cybjhnc@cyber.rdg.ac.uk | TEL:(+44) 1734 318612 |
