Re: Default FS Layout Too Small?

Hi Matthew,

Matthew Seaman wrote:
> Lawrence Stewart wrote:
> 
>> When I last played around with having 1 large partition in the 6.1 
>> days, it didn't actually work consistently. From memory the issue is 
>> that if the boot filesystem (which was on the large root partition) 
>> extended past a particular combination of cyl/head/sector, the machine 
>> would crash in the boot stage. With a 20GB disk it was fine, but a 
>> 40GB disk would trigger the crash.
>>
>> This may have been fixed since then, but it would be worth doing some 
>> testing on a range of hardware before we could recommend it as an option.
> 
> A counter point: we have several hundred servers of various makes[*], sizes
> and ages -- most OS versions since 4.11 right up to 7.1-p3, typically with
> 40+ GB HDDs for the system disk (depending on age -- the most recent 
> machines
> have 160GB) -- all laid out in the all-in-one fashion and we've never 
> seen the
> problem described.  I can only suppose Lawrence ran into a specific 
> motherboard
> or BIOS limitation.
> 

Thanks for the info; it's good to hear you've had no issues with a broad 
base of hardware/software.

I think the "crappy BIOS" option is indeed the most likely cause. In 
trying to remember more details (was back on 2006), I found this in 
boot(8) which I think might have been related to what I eventually 
tracked down:

##########
NOTE: On older machines, or otherwise where EDD support (disk packet
interface support) is not available, all boot-related files and 
structures (including the kernel) that need to be accessed during the 
boot phase must reside on the disk at or below cylinder 1023 (as the 
BIOS understands the geometry).  When a ``Disk error 0x1'' is reported 
by the second-stage bootstrap, it generally means that this requirement 
has not been adhered to.
##########

The machine I was working with was P3 vintage, and I think I saw it on 
an early P4 as well, so whilst modern hardware is most likely not 
affected, older motherboards/BIOSes might still be. I still use P3's for 
home gateway setups and the like.

Anyway, worth having on record in this thread nonetheless, but happy to 
hear it's not an issue with more recent hardware.

Cheers,
Lawrence