Partition of external drive will not mount

Question

Level 1

4 points

Partition of external drive will not mount

I have an external, 3rd party, 1TB HD connected to a MBPro via USB.

I partitioned this drive into 2 parts, one of which I have been using for TM backups. It worked for a month and then the mount of the TM partition started to fail. The partition I use for user space still mounts OK.

My last TM backup was 3 days ago. The TM partition started to fail to mount then. Disk Utility is unable to mount this partition.

Suggestions that do not require reformatting?

TM worked fine in this partictioned HD across USB for quite a while ... finished a backup and then went bad.

Thanks.

MacBook Pro with Retina display, Mac OS X (10.7.4)

Posted on Aug 17, 2012 2:42 PM

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Answer 1

Shootist007

Level 6

16,709 points

Aug 17, 2012 2:49 PM in response to mpage__colo

You have no other option then to Re-Partition and format that drive.

So if the files on the other partition are not on any other internal or external drive copy them to eithe ranother external or internal drive then repartition and format that drive.

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Answer 2

mpage__colo Author

Level 1

4 points

Aug 17, 2012 2:52 PM in response to Shootist007

Any idea what happened to the partition to make it unmountable?

How likely is it to happen again and I end up spending half of my time saving the good partition, reformatting the drive, repartitioning and restoring?

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Answer 3

mpage__colo Author

Level 1

4 points

Aug 17, 2012 9:14 PM in response to mpage__colo

Great idea, Twittly.

I hooked the drive in question up to a 2nd mac and spent about an hour there w/Disk Utility running on the drive and/or the individual partitions.

Never saw a problem!!!!! But ... Diskutility did spend a huge amount of time in fsck_hfs (as shown by Activity Monitor) on the TM partition. that tells me that something is really wrong w/that parttion even though Disk Utility gave it a clean bill of health.

The partition still would not mount, even on the 2nd Mac, even using the Mount command from Disk Utility.

I am now resigned to takng Shootist's recommendation ... or maybe I'll just junk the drive & replace w/something else.

Thanks everyone!!

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Answer 4

Shootist007

Level 6

16,709 points

Aug 18, 2012 1:45 AM in response to mpage__colo

I would get another drive as the one that won't mount you can't trust anymore. Then after you get a new drive and copy all your files over to it I'd then try to re-partition the old drive and used it as a secondary storage drive.

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Answer 5

Aug 18, 2012 5:56 AM in response to Shootist007

I agree with Shootist007, but suggest that you write Zeroes in every block before re-deploying the old drive. This makes certain that every block has "known-Good" data going forward. If a block is Bad, the drive will substitute a spare block to give you 100 percent good blocks.

Writing every block will take several hours to a day to complete. Use the Options button, Seurity Erase, one pass Zero all data. More passes does NOT give more confidence, it just takes longer.

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