Partitioning Issues With OS Sierra (10.12) Disk Utility & Workaround
Recently I've encountered some issues that I believe are unique to Disk Utility in OS Sierra (10.12.3). I wanted to share them because neither I nor an apple support technician on the phone could figure this out. Later, I found that using Disk Utility on a different version of OS worked.
I had an external hard drive from a few years ago (2012ish) which had 3 partitions on it. I wanted to completely erase and repartition the drive. After erasing the drive, Disk Utility in OS Sierra could not partition it. It would always give the same error message reading "MediaKit reports partition (map) too small. If you recently grew your whole-disk, you should run whole-disk repair."
Running a disk repair would reveal no issues or repairs with the drive. On the phone, the Apple technician and I also tried running disk utility from booting in safe mode and still encountered the same problems.
We were also curious as to why whenever we erased the drive, there was still a 32 KB and and an 823.5 MB still used on the drive. When selecting the "higher" disk in the drop down menu on the left, it would show that 32 KB was used. Then selecting the "lower" disk in the same menu showed that 823.5 MB was taken up.
I then had the idea to try partitioning it on a computer running a different version of OS. This one was running OS El Capitan (10.11.6). The first attempt to partition it ran into the same exact problem. However, I then erased the drive using the computer running El Capitan. Once erased, I noticed that the 32 KB from the "higher" disk was now gone. Yet the 823.5 KB in the "lower" disk was still there. Attempting to partition the drive after erasing it on El Capitan was successful.
So there may be a potential issue with OS Sierra's Disk Utility, specifically in erasing drives. I also have a flash drive which I formatted using OS Sierra's Disk Utility that is no longer recognized by other devices.
Below are screenshots documenting the process:
Laptop A: OS X Sierra (10.12.3). Typical error message trying to partition the drive.
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Disc Utility opened on Laptop B running El Capitan (10.11.6). Note the 32 KB in the "higher" drive.
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Lower disc selected in Disc Utility (laptop B) note the 852.6 MB.
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Attempted partition on laptop B, same error.
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Erased disc using laptop B. Note the 32 KB gone.
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However, note the 852.6 MB still there.
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Difference in partition diagram. Unfortunately, I don’t have a screenshot of what it looked like previously, but note how now there are the 3 partitions I am attempting to make. Previously, there would be a 4th partition listed before the 1 TB partition. This was the 32 KB files of some sort that could not be removed, erased, or deleted.
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Successful partition after having erased the disc using a different version of Disk Utility and or different version of OS X. Perhaps there’s something wrong with how OS X Sierra’s Disk Utility is trying to erase drives.
