Resize TrueCrypt Volumes on Mac OS

Follow these instructions to resize TrueCrypt volumes on Mac OS without losing your data.

** Definitely backup your stuff (If your not already, omg.) before attempting this on a live system.

** Proceed at your own risk! This process works great for me, but you may have different results. I am not responsible for anything

Pre-requisites:
- Access to a win* box
- TrueCrypt v6.2a installed on win* box
- Download extcv binaries, available at http://sourceforge.net/projects/extcv
- TrueCrypt volume must not have any ‘hidden’ volumes (they will be destroyed)
- Filesystem on the TrueCrypt volume must use the GUID partition scheme and be formatted as HFS+ (aka Mac OS Extended Journaled)
- Unmount the TrueCrypt image before starting.

Ok, now lets get down to business…

1. Launch ‘extcv’ on the win* box.

2. Select the file that contains your TrueCrypt volume.

3. Enter the new size and go.

** I am assuming you have a solution to move or access your TrueCrypt file from the win* and Mac boxes. I personally just used a WinXP vm in Parallels and used shared folders to access the TrueCrypt file on the Mac.

4. Mount the TrueCrypt volume on your Mac.

5. Launch ‘Terminal.app’.

6. View your volumes and current sizes by executing ‘diskutil list’

laptop01:~ root# diskutil list
/dev/disk0
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *320.1 GB   disk0
   1:                        EFI                         209.7 MB   disk0s1
   2:                  Apple_HFS Macintosh HD            319.7 GB   disk0s2
/dev/disk1
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *128.0 GB   disk1
   1:                        EFI                         209.7 MB   disk1s1
   2:                  Apple_HFS hd                      127.7 GB   disk1s2
/dev/disk2
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:                            t3ch                  *37.6 TB    disk2
/dev/disk3
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme untitled               *524.0 MB   disk3
   1:                  Apple_HFS part1                   100.0 MB   disk3s1

In my scenario, ‘/dev/disk3′ is the TrueCrypt volume and you can see that the size is now 524MB. The partition I want to expand is ‘disk3s1′ which is currently 100MB.

7. View the size limits by executing ‘diskutil resizeVolume disk3s1 limits’

laptop01:~ root# diskutil resizeVolume disk3s1 limits
For device disk3s1 part1:
        Current size:  100.0 MB (100028416 Bytes)
        Minimum size:  100.0 MB (100028416 Bytes)
        Maximum size:  389.8 MB (389767168 Bytes)

Clearly you see that the max size our new partition could be is 389.8MB

8. Now we are going to do the live resize. This is the scary part (double check your backups before completing this step)!

I want my partition to be approximately 250MB. Please read the docs ‘man diskutil’ to see if you want to use different syntax.

Execute ‘diskutil resizeVolume disk3s1 250M’

laptop01:~ root# diskutil resizeVolume disk3s1 250M
Started partitioning on disk3s1 part1
Verifying disk
Resizing
Finished partitioning on disk3s1 part1
/dev/disk3
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *524.0 MB   disk3
   1:                  Apple_HFS part1                   250.0 MB   disk3s1

Confirm the data is still there:

laptop01:~ root# ls -l
total 80
-rw-r--r--  1 root  wheel      3 Nov 19  2008 .CFUserTextEncoding
-r--r--r--  1 root  wheel     10 Jun 23  2009 .forward
drwxr-xr-x  3 root  wheel    102 Feb 23 19:48 .gem
-rw-------  1 root  wheel     35 Jul 22  2009 .lesshst
-rw-------  1 root  wheel   1204 Nov 20 11:30 .localized
drwx------  3 root  wheel    102 Nov 21  2008 .macports
-rw-------  1 root  wheel    253 Dec 10  2008 .mysql_history
-rw-------  1 root  wheel  10139 Mar 12 18:54 .sh_history
drwx------  5 root  wheel    170 Dec 22 11:01 .ssh
drwxr-xr-x  6 root  wheel    204 Nov 21  2008 .subversion
-rw-------  1 root  wheel   9190 Jan 22 13:45 .viminfo
drwx------  9 root  wheel    306 Feb 10 11:49 Library
drwx------  5 root  wheel    170 Nov 19  2008 Library (from old Mac)
drwxr-xr-x  2 root  wheel     68 Mar  8 00:05 test1
laptop01:~ root#

Great, you made it to the end! Hope you enjoyed… Please post comments if you figure out better solutions.

-joe

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