[RndTbl] drive partitioning for Linux install
Dan Martin
ummar143 at cc.umanitoba.ca
Fri Sep 30 17:50:04 CDT 2005
Adam:
Thanks a bunch! That's exactly what the problem is. Soime time ago I
changed my IDE connections, but neglected to change the BIOS. hda used
LBA addressing, but hdc used AUTO, which defaulted to CHS. This
explains some of life's mysteries, like why 2 identical drives appear
different.
I will have to look at partitions on my P4, since the BIOS is set to
AUTO for those, and the drives have both DOS and Linux partitions. I
hope those partition tables are consistent.
I assume the need for LBA settings is relevant only if
1) using DOS, or,
2) using LILO
since Linux does not depend on the BIOS addressing.
Is there ever a good reason to NOT use LBA? [perhaps installing an
ancient drive with stuff on it partitioned under an old scheme?] In
theory, files could be arranged by cylinder to minimize seek times, but
in fact the CHS geometries are not "real" anyways, so no benefit there.
Thanks again.
Adam Thompson wrote:
> Short answer: turn on LBA support in your BIOS. Don't use 'auto' or
> 'large drive support', if you can avoid it, and especially avoid 'chs'
> settings.
>
> That may not be sufficient, it depends on what version of DOS you're
> running.
>
> Unfortunately, if you turn on LBA (or LBA32) mode, your partition
> table will be scrambled... but even worse, if you boot from DOS it
> will still read sector 0 from the drive and infer geometry from what
> it finds there, not from the BIOS. The easiest way around this is to
> turn on LBA, then immediately install Windows 2000 or Windows XP or
> Linux. Don't even try booting DOS until you've successfully recreated
> the partition table under a more advanced OS. Do NOT try "fixing"
> things with PartitionMagic at this point, it will just make a worse mess.
>
> (If you boot a Linux kernel, during the boot sequence it identified
> the disks it found. Output from 'dmesg' should indicate "hda: ....."
> and it should show some sort of indication as to whether the disk
> geometry is in C/H/S mode or LBA mode.)
>
> You might want to read the Large Disk HOWTO, found at:
> http://www.tldp.org/HOWTO/Large-Disk-HOWTO.html as it discusses the
> sort of thing that I think you're running into.
>
> -Adam
>
--
-Dan
Dr. Dan Martin, MD, CCFP, BSc, BCSc (Hon)
GP Hospital Practitioner
Computer Science grad student
ummar143 at cc.umanitoba.ca
(204) 831-1746
answering machine always on
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