Time Machine didn't complete the backup

Hi All,

Trying to figure out why I’m getting this error on my FS repeatedly:

Time Machine couldn’t complete the backup to “Drobo-FS”
The backup disk ran out of space unexpectedly. Time Machine will try to make more space available by removing expired backups during the next scheduled backup.
Open Time Machine preferences to select a larger backup disk or make the backup smaller by excluding files.

I’ve been getting this repeatedly on multiple Macs over the last several days. It doesn’t appear to be doing what it says it is going to do - is there some kind of incompatibility with Time Machine and the FS?

Any way to fix this? I’ve read through multiple Apple notes and tried various methods that have been discussed on various forums around the web. Nothing seems to fix it…

Any advice is greatly appreciated!

  • Thanx
  • Jon

Two things come to mind:

  1. If you haven’t limited the share that Time Machine is using, has it filled up the Drobo FS?
  2. If you did limit it to a particular size, have you reached that?

If there’s still free space on the Drobo FS and the Time Machine share, then I’m not sure what would cause that either.

Hey there diamondsw,

Yes, I set it up as a limited size, and yes, it’s close to full. But I keep getting the warning that I posted. It SAYS that Time Machine will delete expired backups. Hm. So maybe this is normal operation? Every time it does a backup from now on, Time Machine will delete an old backup to make room and inform me that it is doing so?

  • Jon

If the Time Machine volume is close to full, then that’s a normal warning, and indeed Time Machine will delete as many old backups as are necessary to have enough space for the new backup.

Incidentally, this is one situation where I think Time Machine exposes users to unnecessary risk. I created a virtual machine on my MacBook (and hence a really large file), and when Time Machine next ran, it deleted months of old backups without first asking me. By the time I realized what was happening and excluded the VM from Time Machine, it was too late.
There seems to be no limit on what it will delete to make “enough space.”

Odd - what VM program are you using? It should really be excluding such files from backup - I know VMware Fusion does. Any program that doesn’t is making a real amateur hour mistake.

Otherwise, the only thing Time Machine could possibly do different is try to notify you beforehand - but this can be very difficult as it’s not positive how much space is required, and thus how many backups will be deleted. It’s also quite time consuming to figure out how much space an individual backup takes up. Figuring that out ahead of time (rather than just delete old backups as necessary) would be very difficult and slow.

By the way, if you just want to suppress the warning, you can do so in Time Machine preferences inside System Preferences.