Can I safely delete this partition?

Question

I have a MacBook Pro with Bootcamp installed (Windows 7). When I look at the Disk Management console, I that there is a 620MB partition. I am not sure what that is.

Can I safely delete it and extend the Bootcamp partition to it?

Answer 1

DO NOT, UNDER ANY CIRCUMSTANCES, MODIFY YOUR PARTITIONS ON A DUAL-BOOT WINDOWS/OS X (BOOT CAMP) SYSTEM USING THE STANDARD WINDOWS PARTITIONING TOOLS!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Such setups almost always use a hybrid MBR configuration, which is an ugly and dangerous hack used mainly by Apple for dual-booting purposes. A hybrid MBR is an illegal modification of a GUID Partition Table (GPT) in which up to three GPT partitions are copied over to a separate Master Boot Record (MBR) partition table. The trouble is that, although the GPT data structures are the "real" ones, the standard Windows partitioning tools will ignore the GPT data and modify only the MBR data structures. The result can be that the two data structures will go out of sync, and this in turn is very likely to lead to serious data loss. This isn't a theoretical problem, either; I've helped (or tried to help) people who have trashed their installations doing what you're contemplating doing. (Such damage can result in a need to completely re-install everything on the disk.)

If you want to modify the partitions on this disk, you should do so using the OS X disk partitioning tools. This may also require re-creating the hybrid MBR via those tools, gptsync, gdisk, or some other program. Some third-party Windows tools can deal with hybrid MBRs, but aside from my own gdisk, I know relatively little about such tools. I strongly recommend that you read my page on hybrid MBRs (linked to in the previous paragraph) before you muck with this setup.

Of course, this doesn't answer your question of what that 620MB partition is, because your screen shot from the Windows tool doesn't provide any useful clues. You might be able to identify it from OS X, or using a third-party partitioning tool. If I had to guess, I'd say it's an OS X recovery partition, but that's only a guess. Unless and until you do identify it, though, you should not delete it, especially not from the Windows partitioning tool!