Subject: Re: unbootable new disk?
To: David Laight <>
From: Steven M. Bellovin <>
List: current-users
Date: 11/28/2004 15:55:09
In message <>, David Laight writes:
>> Right -- and now that I have it working, I'm quite certain that the 
>> problem is the 137G boundary.  (The disk has a jumper to limit it to 
>> 32G -- which isn't what I bought a 160G drive for...)  
>The 32G boundary is quite a common bios bug - 2^16 sectors.
>> I have two questions now.  The first is whether or not some part of 
>> NetBSD -- sysinst, fdisk, installboot -- should detect the problem and 
>> issue a warning mesage.
>Probably - buy me a big disk (and a system to put it in) and I'll
>do the tests.
>Seriously, part of the problem is having test systems that exhibit all
>the random behaviour of broken BIOS.
>sysinst has a means of restricting root to the start of the disk
>(and having a small root and and large /usr) but that wouldn't be right
>in this case - where it would be better to leave some free space.
>> To me, the clue is the differing numbers of sectors reported by
>> NetBSD and the BIOS.
>I can change sysinst to detect that, and act on it.  But it does get
>hard because some BIOS just lie......
>> The second is what I should 
>> do now: should I try a BIOS update, or should I just repartition the 
>> disk so that wd0a is within the 137G limit?
>You are ok provided /boot and /netbsd reside in the bottom 137G.
>Why the system wasn't booting at all is a different problem.
>> (Actually, the INSTALL 
>> documentation should warn of this, too, and suggest that the default 
>> partitioning -- everything in 'a' -- is a bad idea if you see the 
>> warning about the BIOS versus your disks....)
>Is there a warning about the geometry/size mismatch?
>I've a system where the bios doesn't do LBA at all - but nothing to
>try very big didks on.

I had problems trying to update my BIOS -- I couldn't get a floppy 
drive to work on that machine -- so I repartitioned the disk to keep
/boot and /netbsd near the beginning.  This machine runs -current; I 
expect to have new kernels frequently...

And if I get a chance, I'll craft some warning text for INSTALL.

		--Steve Bellovin,