Disk Utility of 10.6.2 install disk does not recognise SDD; Disk Utility of El Capitan does

First I have to explain the gpt result:

The partition with index 1 is your EFI partition. The partitions with index 2 and 3 are your main OS X volume named Macintosh HD (also visible in the second screenshot) and your Recovery HD. The partition with the index 4 is your NTFS volume WinB (also visible in the second screenshot).

Trying to add a new partition (by using the +-button) or to resize Macintosh HD (by using the handle) with Disk Utility will downsize partition 2 and move partition 3 to the new end of partition 2.

Since adding a new partition with the +-button doesn't work properly for you, you have two options:

• use the handle and resize Macintosh HD. This should create unallocated free space

• or use the +-button and create a new volume. Apparently it will be formatted as a HFS+ Journaled volume.

  • Then boot to Internet Recovery Mode and open Terminal.
  • Enter diskutil list and gpt -r show /dev/disk0.
  • Unmount your main disk with diskutil umountDisk /dev/disk0.
  • Remove the new HFS+ volume with gpt and its index number found above:
    gpt remove -i 4 disk0
  • Enter exit and quit Terminal
  • Reboot

This might break Boot Camp as stated in Disk Utility and is not recommended if Windows boots in MBR-mode. So backup your Mac (including the Bootcamp partition) first.

I tested this with a spare MacBook Air (Mid 2013 with a 250 GB SSD) and a vanilla Yosemite after installing Windows 8.1 R1. Regardless what I did, I had no problem to boot from either Windows 8.1 or OS X. Windows 8.1 seems to be booted in EFI-mode though.

Since you have an older Mac, Windows will probably be booted in hybrid MBR-mode. Adding a fourth partition (at position 3) will break bootability of the last one because only three partitions (and the EFI partition) are allowed.

You could try using bless to verify whether the disk is recognised as bootable and to potentially bless the disk to make it bootable.

If you can boot into Single User Mode (hold down command-S while booting) or launch terminal from an installer disk you can run bless

First I would try to establish if the drive is bootable or is flagged as the boot drive all by using

bless --info /Volumes/yourSSDdrive The state of your drive's blessed system folder

bless --info The state of the current boot drive's blessed system folder

bless --getBoot The current actual logical boot volume (e.g. /dev/disk1 )

If you find your drive is not blessed, you can bless it yourself with

bless --folder "/Volumes/yourSSDdrive/System/Library/CoreServices" --bootinfo --bootefi

See the man page for more details: https://developer.apple.com/library/mac/documentation/Darwin/Reference/ManPages/man8/bless.8.html