[Nook Color Q&A, Help & Troubleshooting] DeanGibson:
Repartitioning the Nook Color for fun and profit.

First, you MUST have a version of busybox (I used v1.17.2) that includes:

fdisk

mke2fs

mkfs.vfat

If you don't have those (verified in the steps below), you will be unable to reformat the new partitions, and will be really screwed. If you have rooted NC 1.2 with the Manual nooter 4.5.6, it includes the required busybox in /system/xbin. The following instructions assume:

that the /system partition on your NC is rooted and intact, AND

that you have archived any B&N purchases back onto the B&N site, AND

that you have saved any of your files from the USB-visible drive onto your PC, AND

that you have backed up your NC using ClockworkRecovery onto an SDcard, AND

that you are booting a rooted OS from a different SDcard.

In the following steps, your partition table should look like this before you start:

Disk /dev/block/mmcblk0: 7944 MB, 7944011776 bytes
255 heads, 63 sectors/track, 965 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

Device Boot Start End Blocks Id System
/dev/block/mmcblk0p1 * 1 9 72261 c Win95 FAT32 (LBA)
/dev/block/mmcblk0p2 10 18 72292+ c Win95 FAT32 (LBA)
/dev/block/mmcblk0p3 19 56 305235 83 Linux
/dev/block/mmcblk0p4 57 965 7301542+ 5 Extended
/dev/block/mmcblk0p5 57 114 465853+ 83 Linux
/dev/block/mmcblk0p6 115 789 5421906 83 Linux
/dev/block/mmcblk0p7 790 834 361431 83 Linux
/dev/block/mmcblk0p8 835 965 1052226 c Win95 FAT32 (LBA)

Here we go ...

Boot some OS that has root access and a way to enter commands (eg, either ConnectBot or ADB) as root.

If you have the above required busybox (v1.17.2) on your bootable SDcard, omit the "xbin/" in each of the command lines below.

If you don't have the required busybox (v1.17.2) on your bootable SDcard, but you have it on your NC (1.2 rooted) internal memory, enter:

mount -t ext2 /dev/block/mmcblk0p5 /data/local/tmp
cd /data/local/tmp

Do:

xbin/busybox fdisk -l /dev/block/mmcblk0

If you don't see a partition table that matches the one above, STOP.

Do:

xbin/busybox mke2fs
xbin/busybox mkfs.vfat

If you get an error message (not found) with either command, STOP. This is important! Help info is OK.

One of the nice things about fdisk (the following steps) is that so long as you don't type 'w" to write the modified table, if you make a mistake, you can quit with 'q' and nothing has changed. Do:

xbin/busybox fdisk /dev/block/mmcblk0

Type the following commands to fdisk. After the first command, you should see your partition table again, and it should look like the copy above.

p
d
8
d
7
d
6
n
(enter to accept the default starting value)
+121
n
(enter to accept the default starting value)
+44
n
(enter to accept the default starting value)
(enter to accept the default ending value)
t
8
c
p

You better see the partition table as shown below. If you do not, you screwed up! In that case, type 'q' (quit) and start xbin/busybox fdisk ... again.

If and only if the partition table matches the one below EXACTLY, type 'w' to write the new partition table to memory. This will produce a warning, requiring a reboot.

Reboot your SDcard and perform steps 1-4 again. If you don't see the new partition table, you screwed up, so continue with the above steps again.

Otherwise, continue with the following steps. MAKE SURE YOU HAVE EXACTLY THE CORRECT COMMANDS AND PARTITION DESIGNATIONS (0p6 THROUGH 0p8) in the steps below, OR YOU WILL FORMAT THE WRONG PARTITION. Note that '5' is right next to '6' on the keyboard, and if you format partition 0p5, you will overwrite your /system partition, and then you will be screwed (but can probably recover by restoring just the "/system" partition w/ ClockworkRecovery, and starting over). Do:

xbin/busybox mke2fs -j -L data /dev/block/mmcblk0p6
xbin/busybox mke2fs -j -L cache /dev/block/mmcblk0p7
xbin/busybox mkfs.vfat -n MyNookColor /dev/block/mmcblk0p8

Power down the NC, and remove the bootable SDcard.

Reinsert the SDcard with your NC backup, and boot the NC into ClockworkRecovery.

Restore your previous NC backup. If you formatted partitions 0p6, 0p7, and 0p8 correctly, the restore should work fine.

Reboot again, this time into the B&N NC software. Everything should work!

Here is what your new partition table should look like:

Disk /dev/block/mmcblk0: 7944 MB, 7944011776 bytes
255 heads, 63 sectors/track, 965 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

Device Boot Start End Blocks Id System
/dev/block/mmcblk0p1 * 1 9 72261 c Win95 FAT32 (LBA)
/dev/block/mmcblk0p2 10 18 72292+ c Win95 FAT32 (LBA)
/dev/block/mmcblk0p3 19 56 305235 83 Linux
/dev/block/mmcblk0p4 57 965 7301542+ 5 Extended
/dev/block/mmcblk0p5 57 114 465853+ 83 Linux
/dev/block/mmcblk0p6 115 236 979933+ 83 Linux
/dev/block/mmcblk0p7 237 281 361431 83 Linux
/dev/block/mmcblk0p8 282 965 5494198+ c Win95 FAT32 (LBA)

Remember, nothing potentially bad happens until you write the partition table, and even then, so long as you don't overwrite the "/system" partition (0p5), your situation should be recoverable. Even then, you should be able to recover by restoring just the "/system" partition w/ ClockworkRecovery, and starting over.

[Edit: This has been automated in two CWR install ZIP files I created. See about 2 pages further down in the thread.]