The hard drive on my MacBook Pro has two partitions. One with the OS and the other with data.
Yesterday, from a USB boot drive, I performed a clean installation of Mountain Lion to the OS drive. I created the USB boot installer from InstallESD.dmg that I received from purchasing the OS from the Mac App Store.
Now I can't see or mount my data partition. I'm wondering if there's a problem with the MBR. In Disk Utility it shows up as "disk0s4", but it's greyed out.
Any ideas on how I can mount the data partition so I can get my data off it?
For diskutil list disk0
the result is:
/dev/disk0
#: TYPE NAME SIZE IDENTIFIER
0: GUID_partition_scheme *500.1 GB disk0
1: EFI 209.7 MB disk0s1
2: Apple_HFS MacBook OS 99.5 GB disk0s2
3: Apple_Boot Recovery HD 650.0 MB disk0s3
4: 46860E2C-2310-4F96-99F6-616D0B4CB55D 399.6 GB disk0s4
Here's the result of diskutil info /dev/disk0s4
Device Identifier: disk0s4
Device Node: /dev/disk0s4
Part of Whole: disk0
Device / Media Name: MacBook Data
Volume Name: Not applicable (no file system)
Mounted: Not applicable (no file system)
File System: None
Partition Type: 46860E2C-2310-4F96-99F6-616D0B4CB55D
OS Can Be Installed: No
Media Type: Generic
Protocol: SATA
SMART Status: Verified
Total Size: 399.6 GB (399629668352 Bytes) (exactly 780526696 512-Byte-Blocks)
Volume Free Space: Not applicable (no file system)
Device Block Size: 512 Bytes
Read-Only Media: No
Read-Only Volume: Not applicable (no file system)
Ejectable: No
Whole: No
Internal: Yes
Solid State: No
Best Answer
Mounting the volume
Disk Utility verification and possible repair of the partition map
If you have not already done so, use Disk Utility 13 (426) in OS X 10.8 to select then verify:
If verification reveals a problem with the partition map, then consider allowing Disk Utility to attempt a repair.
Proceeding without Disk Utility
Credit to Caesium's answer for finding the
asr
suggestion.Here with a disposable JHFS+ volume, an example of adjustments working as expected. Note the file system checks:
If the type of your own
/dev/disk0s4
can not be safely adjusted or (re)set toApple_HFS
then:Relevant lines from
/private/var/log/install.log
should reveal what, if anything, happened todisk0s4
before, during or after installation of the OS todisk0s2
. This logged information may become critical to regaining easy access to the data.Getting the data without mounting the volume
Good luck with your use of Data Rescue 3 – I have the app, but have never attempted to recover from any area of a disk where the partition type has been affected in this way.
Observations
Device/media name
This is sometimes, not always, a match for the volume name. Here for example:
For Todd K., presence of the device/media name –
– raises hope that start and end blocks etc. are good, that only the
type
of the partition is wrong.No Recovery System 10.8 for OS X 10.8
Recovery HD implies Recovery OS 10.7.x.
In any case such as this, an installation that is incomplete (that is without the expected upgrade to the
Apple_Boot
slice) signals that a nonstandard method of installation – with only part of Apple's installer app – may have been used.Side note
GUID Partition Table, as it's described in Disk Utility, is the norm for this type of modern installation of OS X – not Master Boot Record.