I have a few different backups on my desktop mac running 10.8.3 - time machine, carbon copy cloner, and crashplan.
A few days ago, I needed to reinstall my OS for a separate problem with iPhoto that is now resolved. However, after a few days, I noticed that TM had not performed any automatic backups - CCC and CP still backed up normally.
I verified that TM was still on and my backup disk was still correct in System Pref. After selecting "backup now", I noticed that TM will go thru a prolonged period of "preparing for backup" and then stops - without any backup occuring and no error message appearing.
In looking thru the Console log, I consistently see a problem where my backup disc is ejected during this process. I backup to a Drobo external HD that has gone thru a cycle of HD upgrades over the years and, per the Drobo Dashboard software, is performaing normally.
The messages in the Console logs usually involves a "deep event scan" - then some other messages signalling data being copied or old backups being deleted to clear space. Then, there is a message "stopping backup to allow destination disk to be unmounted or ejected", followed by "Cancellation timed out - exiting".
Occasionally, I see a message in TM that backup will continue when the disk is available - although it is clearly mounted in the Finder and I can access the data on it manually.
According to Drobo, I have over 1TB free on my backup volume and Console mentions it needs 650GB (incl. padding).
The old backup data on Drobo is still present and accesible, so I hate to start a fresh backup and lose what's there - although I do have redundancy.
Any help would be appreciated - Thanks!