PARTITION DISK MAC WINDOWS

And the last two partitions are labelled the same because gdisk is translating the MBR type IDs to their GPT equivalents, which are the same for FAT and ExFAT. Is it detecting an old secondary GPT table at the end of the disk, making it think it should still be GPT? This would cause it to think there’s partition overlap even though the disk isn’t GPT at all. Partitions will be aligned on 1-sector boundaries Main partition table begins at sector 2 and ends at sector 33įirst usable sector is 34, last usable sector is 15658974 Warning! Secondary partition table overlaps the last partition byĭisk /dev/disk2: 15659008 sectors, 7.5 GiBĭisk identifier (GUID): 082F14ED-F53A-4922-8382-3BF9908F4433 You will need to delete this partition or resize it in another utility. Warning! Main partition table overlaps the first partition by 32 blocks! Typing 'q' if you don't want to convert your MBR partitions THIS OPERATION IS POTENTIALLY DESTRUCTIVE! Exit by Warning: Devices opened with shared lock will not have their And now we know why diskutil just shows the last partition as Windows_NTFS, because it can’t tell which it actually is without reading the partition’s data itself.

07 is ambiguous - it could be IFS, HPFS, NTFS, ExFAT, or old QNX.

05 is the EBR, covering everything past the third partitionĪnd then in the extended partition table:.

0B is FAT32 with CHS addressing (instead of the newer 0C for LBA addressing I’m guessing this is for max backwards compatibility).

This lets us see the actual hex value partition type IDs in the MBR that Disk Utility chose to assign. (Otherwise you’ll be told “this partition is not enabled” when assigning a drive letter in Disk Management, and reformatting what shows in My Computer will wipe out the primary GPT structures and the ESP in favour of a 200MB FAT volume!)

PARTITION DISK MAC WINDOWS

#1 covers everything from the start of the disk to the end of the ESP and is marked as part of the protective MBR (EE)Īs the linked article explains, hybrid MBRs can be a dangerous hack, and Windows XP can’t actually mount this disk as-is unless the hybrid MBR table is reordered with gdisk to list any mountable partitions before the EE partition.This would in theory allow the disk to mount on older systems that don’t support GPT. If you’ve read that and are wondering why there are no 128MB gaps after each non-ESP partition, note the article doesn’t mention that those gaps are only added after HFS+ partitions when defined directly within the partition table, and not when encapsulated within a Core Storage logical volume group.įor example, an 8GB USB drive partitioned with original Disk Utility to use GPT for two HFS+ partitions looks like:ĭisk: /dev/disk2 geometry: 974/255/63

This follows the behaviour described in Secrets of the GPT. Then our remaining partitions, another boundary alignment gap, and the secondary GPT table and header. The ESP is 409600 sectors * 512 bytes per sector / 1024 bytes per KB / 1024 KB per MB = 200MB. Then at sector 34 there’s a 3KB gap so that the first partition starts on a 4KB boundary (i.e. The protective MBR occupies one 512-byte sector, the GPT header occupies the next sector, and the partition table entries follow. The gpt tool shows everything, and counts according to 512-byte sectors.

Partition disk mac