'looking for backup disk...'

Try re-selecting it via the Time Machine Preferences window.

If that doesn't help, try a "full reset" of Time Machine, per #A4 in Time Machine - Troubleshooting.

Try power-cycling everything. Power off the modem, TC, and Mac. Wait about 5 minutes, then power up the modem. Wait a couple of minutes, then the TC. After a couple more, the Mac.

If that doesn't do it, you may need to reset the TC. See Resetting an AirPort Base Station or Time Capsule FAQ. I think you'll need a "hard reset."

Very strange. 😟

If there were a problem with her backups, you should get a different message. But having tried about everything else, see if you can repair the sparse bundle containing her backups. Selecting Verify Backups from her Mac probably won't work; you'll have to use Disk Utility.

gregmcguire wrote:

. . .

indented, under the sparse file, is 'time machine backups' - i was able to verify this - but like when searching for the backup disk, it just went on and on, not doing anything. eventually had to force quit disk utility...

Do you mean you saw no messages? If so, that's because they often don't appear on the Disk Utility window. As noted in the tan box in #A5b, click the Log icon in the toolbar, or select Window > Show Log from the menubar, to see them.

Don't bother with verifying; just run Repair Disk. Either will take a long time, but twice as long if you run both.

gregmcguire wrote:

so repair disk didn't work either - the log came up with two lines - one saying repair stated, the second saying something about 'expecting dudisk but got nil' - tried it several times, with no success.

Ah, it was totally bunged-up. That likely explains getting the message you did, rather than something indicating a problem with the sparse bundle.

Anyhow, glad it's sorted out.

As this is the top hit when searching for "looking for backup disk" solutions, I thought I would share the solution that worked for me...

It turns out that when trying to play around with the scheduling of Time Machine backups, I inadvertantly altered the ownership on some critical /System/Library/LaunchDaemons plists: com.apple.backupd-attach.plist; com.apple.backupd-auto.plist; com.apple.backupd-wake.plist;com.apple.backupd.plist.

You can check the ownership by typing the following in the terminal:

ls -l /System/Library/LaunchDaemons/com.apple.backupd*

The user (3rd column) should be root and the group (4th column) wheel. If this is not the case then you can reset it using:

sudo chown root:wheel /System/Library/LaunchDaemons/com.apple.backupd*

This will require you to authenticate using an administrator password. I then turned Time Machine off and on again using the System Preferences Pane and everything worked!

I had similar Problems with my Time Machine Backup and wanted to share my solution too, maybe it'll help somebody here.

This solution worked on a Macbook Pro Late 2011 with OS X 10.8.2 Mountain Lion and an external HardDrive connected via USB (so no Time Capsule involved in this case!)

I copied the "com.apple.TimeMachine.Plist" and the "com.apple.TimeMachine.Plist.lockfile" (can be found in /Library/Preferences/) to the Desktop and then deleted both files in the Preferences Folder.

Then I disconnected the HardDrive and turned off Time Machine. Then turned Time Machine back on and plugged the HardDrive back in again. (A new "com.apple.TimeMachine.Plist"-File appeared in the Preference Folder, I deleted that, too.)

Then I started the Backup and it said looking for Backup Disk again, another new "com.apple.TimeMachine.Plist"- File appeared and while Time Machine was searching for the Backup Disk I deleted the File and Time Machine immediately found the Backup Disk and started the Backup process. (Which again created a new "com.apple.TimeMachine.Plist" - File...)

But now it works perfectly again!

Only thing I don't know now is: What should I do with the lockfile I copied to the Desktop? Does anyone know what that file is good for? Do I need to copy it back to the Preferences Folder?

grindchor wrote:

. . .

Then I started the Backup and it said looking for Backup Disk again, another new "com.apple.TimeMachine.Plist"- File appeared and while Time Machine was searching for the Backup Disk I deleted the File and Time Machine immediately found the Backup Disk and started the Backup process. (Which again created a new "com.apple.TimeMachine.Plist" - File...)

It sounds like a backup was still running (or trying to run), so the new plist file got updated with the old values. See #A4 in Time Machine - Troubleshooting

But now it works perfectly again!

Great!

Only thing I don't know now is: What should I do with the lockfile I copied to the Desktop? Does anyone know what that file is good for? Do I need to copy it back to the Preferences Folder?

Not a problem. Those were used only on Lion (dropped in Mountain Lion, but not automatically deleted during the upgrade or migration). They were supposed to protect the actual file from getting updated by two different processes. You'll probably see a bunch of them, all useless on Mountain Lion.

Thanks for the quick reply

Pondini wrote:

It sounds like a backup was still running (or trying to run), so the new plist file got updated with the old values. See #A4 in Time Machine - Troubleshooting

I should have read that before, unfortunatly I haven't found it (thanks google...) It would have saved me a lot of time...

That could have been the problem, because I tried to abort a running Backup Process a few days ago because it was extremly slow, seems that didn't quite work out. (Maybe i should read the "Slow Backup" and "Cancel a Backup" -part on that webpage 😉 )

Pondini wrote:

. . .

Not a problem. Those were used only on Lion (dropped in Mountain Lion, but not automatically deleted during the upgrade or migration). They were supposed to protect the actual file from getting updated by two different processes. You'll probably see a bunch of them, all useless on Mountain Lion.

Alright then Bye Bye lockfile..

Again thank you for your help !

I tried reparing the .sparsebundle file on the time capsule using the instructions from here - http://pondini.org/TM/A5b.html. Everytime I tried to load the .sparsebundle file into Disk Utility, it would hang. So then I would force kill Disk Utility and reopen it and the sparsebundle would be listed on the left side with my other disks. But when I would highlight it, the repair option was grayed out.

I ended up just erasing the whole disk (using http://pondini.org/TM/TCQ5.html) and now the full backup is running and so far so good.

Seems like the .sparsebundle file was corrupted and Disk Utility could not read it (nor Time Machine for that matter)? Not really sure what happened. My sparsebundle file was around 600GB though so not sure if Disk Utility was freaking about the size.

Hopefully the disk is not dying but will keep an eye on it.

smitty25 wrote:

. . .

Seems like the .sparsebundle file was corrupted and Disk Utility could not read it (nor Time Machine for that matter)?

Probably. 😟 Sometimes they get so corrupted that OSX can't even mount them, much less figure out how to fix them -- you might get a "no recognizable file systems found" message. I don't recall one hanging indefinitely like that, but that's a possibility.

If your Time Capsule is more than about 3 years old, the disk could be beginning to fail (drives can fail at any time, of course, but it seems to get more common after about 3 years; but some live for much longer. It's a bit of a crapshoot).

If those are your only backups, you might consider getting an external HD (perhaps a portable), and making "secondary" backups. See Time Machine - Frequently Asked Question #27 for some suggestions.