Partition boundary (was: Extended BIOS translation (worth disabling?))

[Mike Bilow]

Peter Holzer wrote in a message to Mike Bilow:

 PH> Yup. For some reason Linux fdisk (like DOS fdisk) only lets you 
 PH> start partitions at cylinder boundaries. I have considered 
 PH> dusting off Minix fdisk several times, but these days I don't 
 PH> care about a few wasted Megabytes any more, and I haven't had 
 PH> to rebuild strange partition tables for some time.

It is very important that a tool such as fdisk which is made publicly available
only be permitted to start partitions on cylinder boundaries.

There are a number of programs which actually write important information into
the "unallocated" space after either the primary partition sector (also
containing the master boot record) or any extended partition sector.  If this
information is overwritten, then there will be very bad consequences.

Examples of such programs include Ontrack Disk Manager and a number of
anti-virus programs.  In a system configured to use Disk Manager, the managed
partition will become completely inaccessible if the critical data is
overwritten.  This is enough of a problem for Lilo which can hide the
information, but it would be much worse if fdisk were allowed to overwrite it.

To make matters worse, many people using Disk Manager are unaware that they are
using it, because they bought a drive which was prepartitioned for them and
they just plugged it in.  Even on systems where there is no reason to run Disk
Manager because the BIOS fully supports LBA, it is common to find Disk Manager
because this is how many resellers configure all drives by default. They reason
that it cuts their technical support cost because they have no idea whether a
particular buyer has LBA support in the BIOS.

Note that I am by no means defending the wisdom of using unallocated space on
the disk to write critical information, but merely reporting the fact.
 
-- Mike