Wednesday, February 18, 2009

Disk Utility Erase Failed on Mac OS X

Ok, I'm always running out of hard drive space. I just bought a $100 one terabyte external USB 2.0 and eSATA drive to add to my current pile of external hard drives.

Of course it ships formatted FAT32 which Mac OS X can read, but isn't a very good format (doesn't support journaling, limits file sizes to 4 gigs, etc.) So we need to erase and format the drive (or partition or reformat... whatever you want to call it.)

No problem. I launch Disk Utility, select the new drive, and click the Erase tab. Then I select Mac OS Extended (Journaled) as the Volume Format. Then I click Erase. It warns me I'll delete data, blah blah. It starts erasing, and then says the erase failed. Specifically it says:
Volume Erase Failed with error: The underlying task reported failure on exit

After a few more tries I found the solution and it requires changing a setting in the partition. We only want to create a single large partition but we still have to change a setting in the Partition tab.

If you don't see a Partition tab between Erase and RAID try selecting the drive in the list to the left. You may have selected the mount point (or sub volume/partition). To edit the partitions you have the have the higher level drive device media selected.

Ok, after that, click the Partition tab, then select 1 Partition from the Volume Scheme drop down menu. Then click the Options button. Chances are Master Boot Record is selected. You don't want that for a Mac OS Extended format drive. Instead select the GUID Partition Table and click OK (You only want to choose the Apple Partition Map if you are running on a PowerPC Mac with an OS below Mac OS X 10.4 or if you are running a PowerPC Mac and you need the disk to be a startup disk.)

Then click Apply. That should do it.

I haven't been able to reproduce this problem since the Mac OS X 10.6.3 update. If you have this issue and you are running 10.6.3 or newer could you please let me know with a comment below? Thanks!