Subject: Re: AlphaStation 255
To: Robert Elz <kre@munnari.OZ.AU>
From: None <Riccardo.Veraldi@fi.infn.it>
Date: 04/26/2001 09:09:51
okay thank you.
After I got the numbers I do have to build an entry for my nisk in the
disktab file ??
in which way I can instruct NetBSD about my disk geometry ??
On Wed, 25 Apr 2001, Robert Elz wrote:
> Date: Wed, 25 Apr 2001 23:25:20 +0700
> From: Robert Elz <kre@munnari.OZ.AU>
> To: Riccardo.Veraldi@fi.infn.it
> Cc: Ray Phillips <email@example.com>, firstname.lastname@example.org
> Subject: Re: AlphaStation 255
> Date: Wed, 25 Apr 2001 17:07:56 +0200 (CEST)
> From: Riccardo.Veraldi@fi.infn.it
> Message-ID: <Pine.NEB.email@example.com>
> | I installed a IBM DNES 18GB and when I installed the system the default
> | block size and frag size of 80192 amd 1024 where not fine in my case.
> Something is wrong with your disklabel - perhaps you have defined tracks
> that are way too huge, or something odd like that. The cyls/tracks/sectors
> numbers aren't used for anything much related to any modern drive,
> but they can make a huge difference to the way the filesystem works.
> Find numbers that multiply as close as possible to the size of the drive
> (but less or equal, not more), where sectors/track is of the general order
> of 64 (something between 32 and 80), and tracks/cylinder is of the order
> of 20 (10-24 is generally good). Those numbers match the general layout
> style of the SMD drives from which all of this was originally designed.
> For what it is worth, "factor" is an incredibly useful program for
> calculating this stuff. Eg: if you have a drive with 11733120 sectors,
> factor will produce 2 2 2 2 2 2 2 3 3 3 5 7 97 as the prime number factors.
> >From that, sects/track=64 (2^6) tracks/cyl=18 (2*3*3) cylinders=10185
> (3*5*7*97) would be a nice layout to try. (64 * 18 * 10185 == 11733120)
> On an i386 you have to be concerned with the stupid bios limitations
> (so tend to have 63 sects/track, 15 heads (tracks/cyl) etc) - but on
> an alpha there is no suck stupidity to bother with, so just make the
> nicest numbers that fit.
> If factor produces just a few large numbers as factors, then try again
> with a number a few smaller (making it be a multiple of 128 is generally
> good where possible, or 64).