Re: 10.2 Gig HDD

Anthony Barbachan (barbacha@Hinako.AMBusiness.com)
Fri, 22 Jan 1999 00:33:02 -0500

>Hmm, perhaps you can clarify something that confuses me...
>
>If you do invent your own geometry, how does the DRIVE know what you are
>using? Suppose for example, the drive has native geometry of 3200,16,63
>and you decide you want to have less than 1000 cylinders, so you pick
>something like 800,64,63. When the drive is first asked for Sector
>(1,62,54) it can make a good guess that you have got a custom geometry,
>but if you have previously asked it for Sector (1,2,2) will it have
>given you the wrong sector? If not, who told it that the geometry was
>custom... In DOS, perhaps the boot sector? In Linux, the LILO boot
>sector?
>
>This has been bugging me.
>
>Yesterday I performed a horrifically crude hack to get just such a disk
>working on an old machine. The default RH5.2 installation didn't want
>to let us build a single partition due to the disk having more than 1024
>cylinders (and thus LILO might possibly crash and burn). So, not being
>totally confident about hacking the partition table directly with
>Linux's fdisk, I booted DOS (oh the shame :-)) and used MS-fdisk to make
>a partition. This made a suitably translated partition table (roughly
>the above values), which Linux of course happily honoured. (Obviously I
>wiped the DOS partition though.)
>

Now this is problem that can definately be taken care of by Disk Manager.
First of all create a boot floppy and backup boot floppy by dumping a kernel
onto a floppy (dd if=/vmlinuz of=/dev/fd0). Hopefully, for you, your HD
manufacturer will have a freely available copy available for download on
their web site. Get it, put it on a bootable floppy and follow the
instructions to install. Most importantly, since you have a live partition,
choose the UPGRADE option; this will ensure that your current partitions are
preserved. Note: DO NOT choose express install as this will repartition
your drive. Disk Manager will tell you the geometry and the tranlated
geometry during the upgrade process; you may need the translated geometry to
get lilo to install correctly as you may have created you partitions using
the non-translated greometry. Linux switches to the geometry specified in
the partition table during its bootup. After you restart your computer DM
will give you a prompt to allow you to boot from a floppy; choose it and
boot off the boot floppy. After your first bootup run fdisk and check the
geometry, if it matches DM's then you should be ok; just remove any cyl head
or sec options from /etc/lilo.conf and rerun the lilo command. Also make
sure that lilo is installed on the boot partition not the MBR (DM is there);
something like /dev/hda1 instead of /dev/hda. After this Linux should boot
up by itself and you can say bye, bye to the DOS partition. If your
geometry in fdisk does not match the DM geometry (the DM geometry may be off
by one less cylinder; usually ok, use above method) then you will have to
specify the correct translated geometry in /etc/lilo.conf. The correct
geometry for your drive (3200,16,63) is 800,64,63. (The number of heads is
multiplied by the same power of two number that divided the number of
cylinders to a number below 1024, while the new number heads does not pass
254; that uses a different sceme with 15). If you had to use the second
option then, with the correct translated geometry in /etc/lilo.conf, you
should be able to boot Linux after running the lilo command. Remember not
to install lilo to the MBR.

>I'd rather not have to use DOS again in similar circumstances (!)...
>
>I have btw read the Large-disk HOWTO (very educational) but am still
>confused as to the above point.
>
>Neil
>

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