What happens when the Time Machine Drive for multiple Macs is full?

[MrCrowbar]

So here's the deal.

I have a Mac Mini with a big USB hard drive connected to it and 2 Macbooks in the house.
I want to set up the USB hard drive to do the following:
- contain the TIme Machine Backups of the Mac Mini (USB -> folder)
- contain the TIme Machine Backups of Macbook A (network share -> sparsebundle)
- contain the TIme Machine Backups of Macbook B (network share -> sparsebundle)
- contain some other data just to make use of the free space

This all works nicely, the Macbooks back up wirerlessly and the Mac Mini does it via USB.

Now let's assume the USB hard drive is full and I changed a big file on Macbook A and it's starting the Time Machine backup. It would probably start deleting the oldest backups until there's enough space for backing up that big file. But even after deleting every backup but the latest one for Macbook A, there's not enough space for a backup. What happens now? Does it try to delete old backups of Macbook B or of the Mac Mini? It doesn't even have access privileges to those by default.

Or, even worse, let's say the 2 Macbooks and the Mac Mini want to back up at the same time and the backup drive is full. Since Time Capsules are menat to back up multiple Macs simultaniously, I wonder what happens if the drive is full.

The safest bet is probably to have one volume (partition) per computer and one extra partition for expendable data. The only bad thing is that this is super unflexible since Disk Utility can only make partitions smaller and the empty spaces between small volumes can't be claimed back as one big paritition. Any suggestions how I should set it up? Should I just go ahead and have the Mac Mini's backup folder and the Macbooks' sparsebundles in the same volume, aling with some other data?

I'm sure people with Time Capsules have run into that scenario already and can tell me what happens.

 

[old-wiz]

when the capsule fills up it starts overwriting older backups.

 

[MrCrowbar]

when the capsule fills up it starts overwriting older backups.

So, when Macbook A attempts to do a backup and the drive is full, it only deletes its own (Macbook A) old backups and leave everything else alone? This would the delete everyone's backup if they backup at the same time. I wish there was a way to restrict a maximum fackup folder size for each account.

 

[maclover001]

I'm pretty sure a computer can only touch its own backups. If there is not enough space even after erasing as much as possible from it's own backups, it will just error out.

 

[MrCrowbar]

I'm pretty sure a computer can only touch its own backups. If there is not enough space even after erasing as much as possible from it's own backups, it will just error out.

Sound logical. Guess I'll just have to tell everyone to delete some of their old backups if I need space to put some additional junk on the backup drive. Thanks for the info.
I'll get the big drive on monday and let you know if anything weird happens. 1.5 TB hard drives rule!

 

[Scippy]

Couldn't you just partition the drive? That would make each time machine leave the other partitions alone.

 

[old-wiz]

Couldn't you just partition the drive? That would make each time machine leave the other partitions alone.

This is often the best way; it controls the size allowed for each machine.