Time Machine Error Message on Mac Pro

Today I got a Time Machine error message saying that space available for backup was 1.2 TB but it needed 1.4TB for backup. This struck me as a bit odd seeing that I am only backing up 300GB max.

The drive being backed up is my first drive (name Y1 2TB) around 300GB of files and is backed up to my second (name Y2 2TB).

Below are pics of TM windows. I do not have a pic of the error message. The second one appeared while I was writing this post. Notice how it now says that the oldest backup has changed to today at 2:48 pm. All the other are gone when I open TM to look at the backups.

TM has been running since January 31, 2015 and a backup from that date was still on the backup drive an hour ago. Did TM delete the other backups while I was writing this post? Am I missing something here? Keep in mind Macs are new to me.

It seems I should only need to run TM when I have made some major changes like software or hardware installs rather than letting it run continuously. It would be nice if TM preferences allowed one to specify which drives or files to back up rather than which to exclude.

Any comments or suggestions?

Peter B.

TM will delete older backups to make room for new ones when it starts to run out of room. The TM drive should, in general, be twice as big as the drive you are backing up. Not the file sizes, the drive size. So you your first drive is 2TB (taken from the name), then your TM Backup should be about 4TB. I have no idea why it thought it needed 1.4 TB to back up 300GB, unless somehow it's backing up something in addition to the Y1 2TB drive. In any event, if it in fact needed 1.4 TB to backup and you left it running, it deleted older backups to make room. That's how it works. TM by default runs every hour, copying over what changed. If you did something that somehow made TM think that everything on your main drive needed to be backed up, that could trigger the behavior you saw. If you don't want TM to run every hour, then you can turn it off, then only turn it on when you want to make a backup, or you can get TimeMachineEditor (search for it) and set the interval you want. I have my TM backup at noon and midnight, not in between.

Hope that helps some.

MacInWin said:

... If you don't want TM to run every hour, then you can turn it off, then only turn it on when you want to make a backup, or you can get TimeMachineEditor (search for it) and set the interval you want. I have my TM backup at noon and midnight, not in between.

Hope that helps some.

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Thanks Jake that sounds like both will work for me. But I will look for TimeMachineEditor and give it a whirl. I am not too concerned about backs ups of my data, I usually take care of that myself, old habit. It is just the op sys drive that could be a problem if it was not backed up. I have about 15TB of backup drives on my network.

Peter B.

Another solution for the boot drive backup is either Super Duper! or Carbon Copy Cloner. Both will make a bootable clone of the boot drive so that IF the boot drive fails, you can still boot the machine. CCC even makes a clone of the Recovery partition on the boot drive. I don't know about SD! but CCC isn't free, but it's worth every penny. I think both are schedulable and configurable for what and when to back up.

MacInWin said:

Another solution for the boot drive backup is either Super Duper! or Carbon Copy Cloner...I think both are schedulable and configurable for what and when to back up.

Click to expand...

Thanks again Jake, more leads to follow. I will keep you posted.

Peter B.