I'm trying to make a storage partition on my bootable Linux flash drive. It's using GPT and booting with EFI.

|------|-----------------| - - - - - - - |----------|------|
| EFI  |      Linux      |   (storage)   | Recovery | Swap |
| 500M |      ~28GB      |     32GB      |    2GB   |  1G  |
|------|-----------------| - - - - - - - |----------|------|

(Not to scale: EFI, swap, and recovery are much smaller. Recovery is a bootable Ubuntu Live CD installation.)

I used GParted to format the (storage) partition to NTFS. Then I erased the volume using GParted. But when I rebooted to Mac, Disk Utility doesn't see the free space at all. I clicked Partition to try to reformat the volume, and got this:


Yes, it's really around 28 GB, as the number says...but the picture shows it taking up nearly the entire disk!

Before I deleted the provisional partition, it showed up but gave me a different error when I tried to reformat - something along the lines of "couldn't modify partition map".


I suspect the issue you encountered is because Intel-based Mac OS X uses a combination of GPT and MBR for partition tables.

After you finish partitioning, use the command
sudo gptsync /path-to-disk-device
to resync GPT with the MSDOS partition table. The gptsync command is included with the GParted Live media.

See GParted FAQ - How can I fix missing or lost partitions on Intel-based Mac OS X? .

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