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Setting active partition & default boot - very puzzled


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#1
Flobbleobble

Flobbleobble

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I'm in the process of migrating from Lion to Mountain Lion, and simultaneously from HDD to SSD for my system disk.

My SSD has two partitions, one with Lion, one with Mountain Lion (ML), the HDD also has two partitions, also with Lion and ML - I cloned the HDD onto the SSD, and will remove the HDD once I have everything working.

In the BIOS I have set the boot order so it boots from SSD first. This works fine.

Once the bootloader has started, I can manually select Lion or ML, from either the SSD or the HDD. All work fine.

I can select which OS boots by default by setting the Default Partition flags in org.Chameleon.boot.plist on the SSD Lion partition. This works fine, but implies that the SSD Lion partition is set active.

I want to eventually retire the Lion partitions, which means I want to boot fully from the ML partition. But I cannot for the life of me figure out how to make the Lion partition active.

I'm also struggling to relate the output of "diskutil list" and the partition tables I can extract from fdisk.

Here's the diskutil output. You can also see my DATA disk.


/dev/disk0
#: TYPE NAME SIZE IDENTIFIER
0: GUID_partition_scheme *128.0 GB disk0
1: EFI 209.7 MB disk0s1
2: Apple_HFS SSD Mountain Lion 63.8 GB disk0s2
3: Apple_HFS SSD Lion 63.7 GB disk0s3

/dev/disk1
#: TYPE NAME SIZE IDENTIFIER
0: GUID_partition_scheme *300.1 GB disk1
1: EFI 209.7 MB disk1s1
2: Apple_HFS MountainLion 100.4 GB disk1s2
3: Apple_HFS Lion 199.2 GB disk1s3

/dev/disk2 #: TYPE NAME SIZE IDENTIFIER
0: GUID_partition_scheme *1.0 TB disk2
1: EFI 209.7 MB disk2s1
2: Apple_HFS DATA 999.7 GB disk2s2


Here's the partition table for the SSD:



Disk: /dev/disk0 geometry: 15566/255/63 [250069680 sectors]

Offset: 0 Signature: 0xAA55

Starting Ending

#: id cyl hd sec - cyl hd sec [ start - size]

------------------------------------------------------------------------

1: EE 1023 254 63 - 1023 254 63 [ 1 - 250069679] <Unknown ID>

2: 00 0 0 0 - 0 0 0 [ 0 - 0] unused

3: 00 0 0 0 - 0 0 0 [ 0 - 0] unused

4: 00 0 0 0 - 0 0 0 [ 0 - 0] unused


Here's the partition table for the HDD:



Disk: /dev/disk1 geometry: 36481/255/63 [586070255 sectors]

Offset: 0 Signature: 0xAA55

Starting Ending

#: id cyl hd sec - cyl hd sec [ start - size]

------------------------------------------------------------------------

1: EE 1023 254 63 - 1023 254 63 [ 1 - 586070254] <Unknown ID>

2: 00 0 0 0 - 0 0 0 [ 0 - 0] unused

3: 00 0 0 0 - 0 0 0 [ 0 - 0] unused

4: 00 0 0 0 - 0 0 0 [ 0 - 0] unused


Now for the things I don't understand.


  • Why don't the partitions listed in diskutil appear in the fdisk output?
  • Why don't the partition names appear in the fdisk output?
  • Why are none of the partitions in fdisk output shown as 'active', ie, no * next to the id number
  • If there's no active partition, why is my system booting just fine?


Very puzzled, and I don't want to start messing around with partition tables etc until I understand what's going on...

#2
3.14r2

3.14r2

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Use a PartedMagic Live CD and launch Gparted to check what partitions have "boot" flag set and change it if needed. It's quite visual and easy to use.





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