Time Machine Backup Fails - backup disk is unmounted during backup

I had the same trouble with a Seagate 1.5 TB external hard drive. I had to reformat it for my iMac. It would work sometimes and sometimes not. What finally worked for me was one of the following, maybe all of them:

1. Check to see if the drivers are still on the external drive. If not, got to website and download them.

2. In Preferences > Energy Saver, uncheck the option "put the hard disk(s) to sleep when possible."

3. A little free app: Keep Drive Spinning.app

I'm not in the process of eliminating numbers 2 and 3 to see if number 1 was the real problem. I'm just glad it's working now.

I have had a related problem.

Over the last three-four years of using TimeMachine I have had FOUR (4) disk drives fail on me. In the first instance, the power supply failed twice. Switching from connection via Firewire to USB seemed to solve that problem.

Then in May 2011 I bought TWO x Freecom HD 1 TB portable drives, I indicated to the Apple retailer, YooBee, expressly for use as TimeMachine backups.

They have both FAILED for me, as per the description below, which I have filed on the Freecom support site.

So FOUR disk drives failing over 3 to 4 years is beyond bad luck, beyond coincidence, but 'conspiracy' as Churhill might have put it. The common factor is that all four disks failed 'on watch' as being my TimeMachine drives. I am VERY ALARMED at his rate of failure, and wonder if there is a fault with TimeMachine in burning out the disks through some feature of excess use?

I note the detailed advice here is pertinent ... but I've only just found it!

Backup, restoring, formatting info: Apple Support Communities. (n.d.). Retrieved January 16, 2012, from https://discussions.apple.com/thread/3358920

Message to Freecom Support Forum 2012-1-14, and YooBee.

I was absolutely assured by my Apple Mac (YooBee, 123 Broadway, Newmarket) store that these drives would be perfect for TimeMachine backup. But to have TWO fail within 8 months of purchase is very, very, very alarming. One failing is bad luck. Two failing is more than coincidence....

There was an alarming clicking noise from the disks.

Disks were disconncted from USB.

Message from Mac saying USB drive disconnected incorrctly. I DID NOTHING: Timemachine was just in the middle of doing a backup, perhaps. I was just working away when I noticed the tiny noise, above.

I turned of Timemachine in preferences. Physically powered down and disconnected Freecom drive. Waited. Reconnected. Unable to remount. Used Disk Utility to mount, and initiated Repair.

Message Apple disk utility

Verify and Repair volume "MELLALIEU-01-FREECOM-HDD-1TB"

Checking file system

Volume repair complete

Updating boot support partitions for the volume as required

Error: disk Utility cant repair this disk. Back up as many files as possible, reformat the disk, and restore your backed up files"

Another message

Mac OS X can't repair the disk

MELLALIEU-01-FREECOM-HDD-1TB

You can still open or copy files on the disk, but you can't save changes to files on the disk. Back up the disk and reformat it as soon as you can.

Well: the Freecom is not able to be remounted, even after plugging, and replugging the USB.

This happened with TWO drives.

And despite the suggestion to backup the files NONE are accessible.

This is NOT what I expect to have happen with drives expressly purchased for use as TimeMachine backups.

I managed to reformat the one that first failed, about two months after purchase. I have not attempted to reformat the latest failure-- and loose my complete Timemachine backup. Naturally, I don't use the reformatted disk for Timemachine, but a Vault for Aperture.

Equipment specification and serial numbers:

Freecom HD Mobile Drive xxs 1 Tb x 2

model SSYAAA P/N 35154

Purchased May 2011, YOOBEE, Newmarket.

S/N 351540442100051.

S/N 351540442100021.

I am getting a similar error with Disk Utility:

Checking catalog file.

Invalid key length

The volume TimeMachine M1 could not be verified completely.

Volume repair complete.Updating boot support partitions for the volume as required.Error: Disk Utility can’t repair this disk. Back up as many of your files as possible, reformat the disk, and restore your backed-up files.

I'll disable Time machine for the moment and try again....

NicFromOz wrote:

. . .

Error: Disk Utility can’t repair this disk.

No, that means what it says -- the backups are damaged beyond DIsk Utility's ability to repair them.

it's possible a heavy-duty 3rd-party disk repair app, such as DiskWarrior, can. These are expensive (DiskWarrior is about $100), and probably a good investment for the future, but there's no guarantee it will work.

If it can't, or if you don't want to spend the money, erase the disk (and take the time to click Security Options, then either Zero Out Disk (Snow Leopard or earlier) or Fastest (Lion). That will take much longer, but if it fails, you know the disk has failed. If it succeeds, the disk may be ok.