De-partitioning a Mac disk

I wrote yesterday about NTFS-3G because I was backing my MacBook to an external NTFS drive. I was backing up because I wanted to de-partition my Mac.

When I upgraded my MacBook to a bigger drive, more RAM, and OS X 10.5, I partitioned the drive. I created two 25GB partitions with the intention of putting Windows and Linux on them with BootCamp. It turns out that BootCamp doesn't like that. It wants the system drive to have only one partition, which it would shrink. I never bothered to go any further.

The disk has been filling up recently and I wanted the extra space back, to extend my primary HFS+ partition by 50GB. I found a guide to nondestructively resizing volumes with the command-line diskutil tool.

With some trepidation, I set out to reclaim the end of my drive. Happily, it turned out to be both quick and painless.

Here's the old disk layout:

georger@georger-macbook:~$ diskutil list
/dev/disk0
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *298.1 Gi   disk0
   1:                        EFI                         200.0 Mi   disk0s1
   2:                  Apple_HFS GeorgeR Mac             250.0 Gi   disk0s2
   3:       Microsoft Basic Data WINDOWS                 25.0 Gi    disk0s3
   4:       Microsoft Basic Data LINUX                   22.8 Gi    disk0s4

First, I merged the two FAT32 partitions into one HFS+ partition:

georger@georger-macbook:~$ sudo diskutil mergePartitions \
    "Journaled HFS+" End disk0s3 disk0s4
The chosen disk does not support resizing, do you wish to format instead? (y/N) y
Merging partitions into a new partition
     Start partition: disk0s3 WINDOWS
     Finish partition: disk0s4 LINUX
Started erase after partitioning on disk disk0s3
Erasing
Mounting disk
[ + 0%..10%..20%..30%..40%..50%..60%..70%..80%..90%..100% ]
Finished erase after partitioning on disk disk0s3 End
/dev/disk0
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *298.1 Gi   disk0
   1:                        EFI                         200.0 Mi   disk0s1
   2:                  Apple_HFS GeorgeR Mac             250.0 Gi   disk0s2
   3:                  Apple_HFS End                     47.6 Gi    disk0s3

Then, I merged the two HFS+ partitions:

georger@georger-macbook:~$ sudo diskutil mergePartitions \
    "Journaled HFS+" End disk0s2 disk0s3
Merging partitions into a new partition
     Start partition: disk0s2 GeorgeR Mac
     Finish partition: disk0s3 End
Attempting resize
Changing filesystem size on disk 'disk0s2'...
Attempting to change filesystem size from 268435456000 to 319728959488 bytes
/dev/disk0
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *298.1 Gi   disk0
   1:                        EFI                         200.0 Mi   disk0s1
   2:                  Apple_HFS GeorgeR Mac             297.8 Gi   disk0s2

And everything is good:

georger@georger-macbook:~$ df
Filesystem    512-blocks      Used     Avail Capacity  Mounted on
/dev/disk0s2   624470624 508168048 115790576    81%    /

Disclaimer: back your disk up and read the diskutil man page very carefully before using: one misstep could ruin the contents of your disk.