External Hard Disc won't mount - Partition Map error. Can't repair with Disk Utility

Question

Level 1

9 points

External Hard Disc won't mount - Partition Map error. Can't repair with Disk Utility

Happy New Year all and thanks in advance for any support/advise.

I have some important data on an external drive that does not seem to want to mount. The drive is a 500 GB Seagate connected via USB. I am currently on an iMac 3.06 GHz Intel Core 2 Duo running Yosemity 10.10.1

What I've tried:

Multiple computers - connected the drive to various apple computers with the same result.

New enclosure: I have removed the actual HD from the enclosure and connected it using a new one.

Disk Utility: Verifying Disc reports the following error: 'Error: Partition map check failed because no slices were found.' Screenshot below:

I have searched this and other forums and run a few commands in Terminal that seem relevant to the issue, but am out of my depth in terms of interpreting the results. Thank again for your attention!!!

Commands run in Terminal:

diskutil list

diskutil cs list

mount

diskutil info disk1

Full Results pasted below:

diskutil list...

Ethan-Smiths-iMac:~ Ethan$ diskutil list

/dev/disk0

#: TYPE NAME SIZE IDENTIFIER

0: GUID_partition_scheme *1.0 TB disk0

1: EFI EFI 209.7 MB disk0s1

2: Apple_HFS Macintosh HD 999.3 GB disk0s2

3: Apple_Boot Recovery HD 650.0 MB disk0s3

/dev/disk1

#: TYPE NAME SIZE IDENTIFIER

0: GUID_partition_scheme *500.1 GB disk1

1: Microsoft Reserved 134.2 MB disk1s1

diskutil cs list...

Ethan-Smiths-iMac:~ Ethan$ diskutil cs list

No CoreStorage logical volume groups found

mount...

Ethan-Smiths-iMac:~ Ethan$ mount

/dev/disk0s2 on / (hfs, local, journaled)

devfs on /dev (devfs, local, nobrowse)

map -hosts on /net (autofs, nosuid, automounted, nobrowse)

map auto_home on /home (autofs, automounted, nobrowse)

diskutil info disk1...

Ethan-Smiths-iMac:~ Ethan$ diskutil info disk1

Device Identifier: disk1

Device Node: /dev/disk1

Part of Whole: disk1

Device / Media Name: ST950032 5AS Media

Volume Name: Not applicable (no file system)

Mounted: Not applicable (no file system)

File System: None

Content (IOContent): GUID_partition_scheme

OS Can Be Installed: No

Media Type: Generic

Protocol: USB

SMART Status: Not Supported

Total Size: 500.1 GB (500107862016 Bytes) (exactly 976773168 512-Byte-Units)

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: Yes

Whole: Yes

Internal: No

OS 9 Drivers: No

Low Level Format: Not supported

iMac (27-inch Late 2009), OS X Yosemite (10.10.1)

Posted on Jan 13, 2015 9:41 AM

Reply

Answer 1

Kappy

Level 10

361,741 points

Jan 13, 2015 9:53 AM in response to Fundido0

Firstly, you are not creating CoreStorage volumes, so what you hunted for isn't much use to you. You need to try this:

Drive Partition and Format

1. Open Disk Utility in your Utilities folder.

2. After DU loads select your hard drive (this is the entry with the mfgr.'s ID and size) from the left side list. Click on the Partition tab in the DU main window.

3. Under the Volume Scheme heading set the number of partitions from the drop down menu to one. Click on the Options button, set the partition scheme to GUID then click on the OK button. Set the format type to Mac OS Extended (Journaled.) Click on the Apply button and wait until the process has completed.

4. Select the volume you just created (this is the sub-entry under the drive entry) from the left side list. Click on the Erase tab in the DU main window.

5. Set the format type to Mac OS Extended (Journaled.) Click on the Security button, check the button for Zero Data and click on OK to return to the Erase window.

6. Click on the Erase button. The format process can take up to several hours depending upon the drive size.

Steps 4-6 are optional but should be used on a drive that has never been formatted before, if the format type is not Mac OS Extended, if the partition scheme has been changed, or if a different operating system (not OS X) has been installed on the drive.

If you still have a problem then the drive may be bad.

Reply

Answer 2

Fundido0 Author

Level 1

9 points

Jan 13, 2015 10:13 AM in response to Kappy

Hello Kappy, thanks so much for your time. Before I follow the instructions I just wanted to make sure that I won't be wiping all data from the drive. My hope is to recover what's on there. Thanks again!

Reply

Answer 3

Kappy

Level 10

361,741 points

Jan 13, 2015 10:21 AM in response to Fundido0

You can try this:

sudo diskutil mountDisk /dev/disk1/

Press RETURN, enter your admin password when prompted and press RETURN again.

If a named volume appears then you are good. Otherwise, you need to repartition the drive.

Reply

Answer 4

Fundido0 Author

Level 1

9 points

Jan 13, 2015 11:36 AM in response to Kappy

No dice, the command returns this:

Unable to find disk for /dev/disk1/

Is there any way to repartition without wiping the drive? Or copying the drive onto a working drive before repartitioning? If not, might it be worthwhile to bring it to someone who specializes in data retrieval?

Reply

Answer 5

Kappy

Level 10

361,741 points

Jan 13, 2015 11:46 AM in response to Fundido0

No. Partitioning is a destructive process.

Retry the previous command line this way: sudo diskutil mountDisk /dev/disk1

Reply

Answer 6

Fundido0 Author

Level 1

9 points

Jan 13, 2015 11:50 AM in response to Kappy

Okay, so I retried with the revised command and got this:

Volume(s) mounted successfully

Sounds encouraging. What next? Also, what was the difference in the commands - they look the same?

Thanks!

Reply

Answer 7

Kappy

Level 10

361,741 points

Jan 13, 2015 11:54 AM in response to Fundido0

The "/" at the end. Open Disk Utility and see if you have an accessible drive listed with a named volume below the drive entry rather than "disk1s1."

Reply

Answer 8

Fundido0 Author

Level 1

9 points

Jan 13, 2015 12:11 PM in response to Kappy

Negative, here's a screenshot of what I have in Disk Utility (I tried quitting the program and reopening the program as well):

Here is a shot of what I got in Terminal (I entered the password incorectly the first time):

Reply

Answer 9

Kappy

Level 10

361,741 points

Jan 13, 2015 2:04 PM in response to Fundido0

Select the disk1s1 volume under the main drive entry, then click on the Mount icon in the Disk Utility toolbar if it goes active and see if a volume then mounts on your Desktop. If it does not, then you need to reformat the drive. And, you cannot access the volume in order to copy your data somewhere else. If you are willing to spend money on the problem, then you can always try using a software recovery utility:

General File Recovery

If you stop using the drive it's possible to recover deleted files that have not been overwritten by using recovery software such as MAC Data Recovery, Data Rescue II, File Salvage or TechTool Pro. Each of the preceding come on bootable CDs to enable usage without risk of writing more data to the hard drive. Two free alternatives are Disk Drill and TestDisk. Look for them and demos at MacUpdate or CNET Downloads. Recovery software usually provide trial versions that enable you to determine if the software would help before actually paying for it. Beyond this or if the drive has completely failed, then you would need to send the drive to a recovery service which is very expensive.

The longer the hard drive remains in use and data are written to it, the greater the risk your deleted files will be overwritten.

Also visit The XLab FAQs and read the FAQ on Data Recovery.

Reply