TimeMachine volume keeps unmounting

[GoodWatch]

I recently took delivery of a 27" i7 iMac with 16 GB memory, 3 TB Fusion Drive and the NVIDIA GeForce GTX 780M 4096 MB. Very nifty. But after migrating the 'old' to the new Mac, my external USB 2 TimeMachine drive (volume) started to unmount itself spontaneously. This never, ever happened with the 2009 21" Mac I was using it before. Today I bought a brand new 2 TB external USB 3 drive and designated that as my TimeMachine drive. And lo and behold: it unmounted spontaneously, disrupting the backup.

Is this a known problem and is there a solution?

Thanks in advance for your efforts!

 

[WilliamG]

I recently took delivery of a 27" i7 iMac with 16 GB memory, 3 TB Fusion Drive and the NVIDIA GeForce GTX 780M 4096 MB. Very nifty. But after migrating the 'old' to the new Mac, my external USB 2 TimeMachine drive (volume) started to unmount itself spontaneously. This never, ever happened with the 2009 21" Mac I was using it before. Today I bought a brand new 2 TB external USB 3 drive and designated that as my TimeMachine drive. And lo and behold: it unmounted spontaneously, disrupting the backup.

Is this a known problem and is there a solution?

Thanks in advance for your efforts!

What kind of migration did you do? I'd suggest that maybe the cause of the issue... I'd do a fresh installation, manually copy whatever files you need across from the old system to the new one, and go from there.

 

[GoodWatch]

What kind of migration did you do? I'd suggest that maybe the cause of the issue... I'd do a fresh installation, manually copy whatever files you need across from the old system to the new one, and go from there.

I used the migration assistant. Alas, the old machine was wiped after a couple of days because it was part of a deal and had to be returned. And I reformatted the old drive to be used elsewhere. I can't go back any more. Thanks for your reply. I still have the same problem. After a while the drive just disapears from the desktop and has to be activated again.

 

[WilliamG]

I used the migration assistant. Alas, the old machine was wiped after a couple of days because it was part of a deal and had to be returned. And I reformatted the old drive to be used elsewhere. I can't go back any more. Thanks for your reply. I still have the same problem. After a while the drive just disapears from the desktop and has to be activated again.

Copy any data you need to an external drive, and reinstall the OS fresh.

 

[nebo1ss]

How are you connecting the new drive to the computer are your doing so directly or using something like the shared USB on an AIRPORT EXTREME.

The only time I have experienced this problem with Time machine was when the drive was connected through the Airport Extreme.

 

[macthefork]

There were quite a few people that had this issue when the 10.8.5 update first was released and installed. The issue has since been corrected in Apple's latest 10.8.5 update. I'm wondering it your iMac may have the earlier version of the update installed. Our 2013 iMac had this problem and I had to revert back to 10.8.4, which corrected the problem at the time.

You can download the combo update, that has the corrected 10.8.5 update on it. This may correct your problem.