Today I saw for a very brief moment (like a fraction of a second) an alert telling me that some “BaseSystem.dmg” file was being mounted, even though I wasn’t trying to mount anything, nevertheless a strange image.

So my question is: Is it possible to see a log of anything (and everything) that was mounted on my system?

1 Answer 1


This is normal and you need not worry about it.

When certain system items are updated, a recovery partition is mounted to update the boot (or other) configuration. It is then un-mounted, all without showing a icon for the drive on the desktop.

You can see the recovery partition by issuing diskutil list in a terminal window.

You should see something like:

   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *1.0 TB     disk0
   1:                        EFI EFI                     209.7 MB   disk0s1
   2:                  Apple_HFS HARDDRIVE               499.7 GB   disk0s2
   3:                 Apple_Boot Recovery HD             650.0 MB   disk0s3

The Recovery HD is the one that is mounted.

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