External disk partitioning for Windows and OS X backup

Based on the partition GUIDs.

disk1s2, disk1s3, disk1s5 = GPT2, GPT3 and GPT5 have a partition GUID of Windows Microsoft Basic Data.

disk1s4 = GPT4 is HFS+

There is no MBR covering disk1, so OSX will not boot from a Microsoft Basic Data, unless there is a corresponding MBR entry. If you really want to dig further, you can look at 'man bless' and --legacydrivehint qualifier on how the Mac Bootmanager handles it.

BroFlav wrote:

disk1s2, disk1s3, disk1s5 = GPT2, GPT3 and GPT5 have a partition GUID of Windows Microsoft Basic Data.

That's weird because those partitions have been made under OS X, using Disk Utility first, then CCC to clone the OS X partitions. So how have they been marked as Microsoft Basic Data...

Do you have the GPT, before they were cloned by CCC? Did CCC mark these as MSD types?

There is no MBR covering disk1, so OSX will not boot from a Microsoft Basic Data, unless there is a corresponding MBR entry. If you really want to dig further, you can look at 'man bless' and --legacydrivehint qualifier on how the Mac Bootmanager handles it.

So bless can be used to force a disk to be bootable?

You need both, a MBR and the bless with --legacydrive hint to make it work. This is what Startup Disk will do, when you click on Restart after selecting a Bootcamp partition in Startup Disk. You can check that in the Console logs. The partition must have an MBR, must be readable by Apple NTFS driver (not any other third party driver) and be blessed before it will boot from it.

BTW, I am great fan of Cosby. That picture says a thousand words. Very 😎.