Last Friday I used tomsrtbt to delete an unused partition and grow
another partition using the newly freed space. Since many people
on this list have expressed an interest in using tomsrtbt to copy
partitions, I thought I would share my experience with a different
kind of partition problem.
Background: A year ago I split an active Windows 95 partition in
two using the freeware utility 'fips'. One half continued to run
Windows 95; the other was reformatted and repartitioned to run
Linux. After a year it became apparent that 1) the Windows 95
partition was running out of space and 2) the linux partition was not
being used.
The problem: How to combine the two partitions back into a single
Windows 95 partition, without disturbing the existing Windows 95
data?
The solution:
I carefully read the fips documentation to get an idea of how fips
splits partitions. I concluded that apart from obvious changes to
the partition table, fips merely changes the total sector count in the
Dos Boot Record (DBR) to match that of the new partition table
entry and leaves the FAT (file allocation table) alone. Apparently
DOS simply ignores FAT entries which point to clusters beyond
the end of its data area.
I then consulted Scott Mueller's excellent *Upgrading and Repairing
PCs* in order to determine the layout of the partition table and dos
boot record data structures. As a concession to my paranoia, I
verified that the existing FAT was the right size for the entire disk
drive and conversely was larger than necessary for the existing
partition.
As further insurance against disaster, I used netcat to make a
complete byte for byte copy of the disk drive onto a machine with a
large disk drive. I described my method for doing this is in an
earlier posting.
Using tomshexd, the hexdump utility supplied with tomsrtbt,
hexadecimal dumps of the partition table and dos boot record were
printed as well as saved to diskette.
I then deleted all the partitions (yes, including the active Win95
partition!) using fdisk and created a single partition spanning the
entire drive. The Partition Id was changed to '6' (DOS 16-bit >= 32
M) and the boot flag enabled for the new partition.
Scott's book in hand, I used tomshexd to look at the new partition
table. The total number of sectors contained by the new partition
were determined and then written down.
Using the vi supplied on tomsrtbt, I then edited the hex dump of the
dos boot record, replacing the total sector count with the count
listed in the new partition table. The -o option of tomshexd was
used to create a binary image of the boot record which was written
out to disk using dd.
The computer was booted up in Windows. I checked the capacity
of the drive: the new disk space was there! A scandisk was done
and no errors were found. New Windows software was installed
without incident and the computer has worked without a problem
since then.
I was struck once again by the ease with which tomsrtbt handled a
project which otherwise would have required expensive proprietary
tools. Having successfully merged partitions, I am curious to hear
other ways that people have used tomsrtbt to manipulate partitions.
Does anybody have any experiences in this area they'd care to
share?
