Forum Question: Time Capsule for 2 Macs

Dear Garry,

We have been enjoying your podcasts – thank you!

We have a time capsule to work as a backup drive for our iMac and our Macbook Pro using time machine. The problem is that both computers compete for space on the time capsule and one always runs out of space. This was my Macbook since it is not always connected to our network, and the iMac gobbled up so much space on the time capsule that eventually the backup of the Macbook would not fit anymore and break off with an error.

I erased both sparse bundles and started afresh, making sure that both machines got more than their harddrive’s worth in space. But once again I keep getting an error now when my Macbook is trying to back up. Its sparse bundle on the Time Capsule is 200 GB for a 160 GB harddrive with about 80 GB in use – should be enough. But instead of erasing older backups I again get a message that there is not enough room on the backup drive, and the backup is broken off. Aggravating!

Is there anything you know that we might try short of constantly flushing the entire time capsule and keep starting over? It would be so easy if it could be divided into two partitions, but I haven’t found a way to do that.



— Rainer

Comments: 10 Responses to “Time Capsule for 2 Macs”

    12/11/09 @ 5:21 pm

    From what I have heard, you shouldn’t get that sort of error. TC should be able to handle more than one backup without them competing for space like that. But I can see how it would happen anyway if a lot of files suddenly changed and a large chunk needed to be backed up.
    I don’t use TC myself (I have a networked drive using TM, but it isn’t a TC) so I can’t test first-hand.

      12/12/09 @ 2:31 am

      I would not need a backup every hour, that is way too much for my use! One per day, or one avery couple of days would easily be good enough for me!

      Do you know any tricks how I could coerce time machine to slow down with the backups?

    Michael Kukielka
    12/11/09 @ 5:28 pm

    I had the same problem when my 1TB TC started running out of space while backing up 3 Macs. It prompted me to allow the Time Machine to delete older backups and I said yes. I had to say yes to this several times for several weeks before it stopped asking again. I haven’t had the problem since and I’m not sure why (I know this won’t help you).

    The alternative is to attach an external HD to the Time Capsule and set the MacBook to target the attached HDD for the Time Machine.

      12/12/09 @ 2:28 am

      I have had that, too, but now I get a different message saying this backup is too large for the volume and that I should choose a different volume. Somehow the older backups are not deleted and I don’t even get that option anymore.

      There ought to be enough space since only about 80 GB are in use on my MBP, and the sparse bundle for it has 200 GB. I tried openig it and manually erasing some older bands in it, but it won’t allow that, either.

    12/11/09 @ 5:30 pm

    I had a similar problem. Went to connected drive for iMac and used TM exclusively for MacBook. TM has very limited config abilities. No partitioning either.

    Michael A.
    12/11/09 @ 5:53 pm

    It is possible to limit the size of a Time Machine backup image (sparsebundle) using the ‘hdutil’ terminal command. I haven’t had to do it (I only backup one Mac to my backup disk) but it seems straightforward enough. In theory this causes the Time Machine backup to purge when it hits the artificial limit you set, rather than waiting to fill up the drive. See discussions here

    and here

    and be sure to read the comment about “resize” on that second link.

      12/12/09 @ 3:06 am

      Thanks for the tip, Michael! But I feel like I am going in way over my head with this!

      I wonder if there is not an easy way to use an image with a fixed size to back up into. I can try the described terminal commands to convert the sparse bundle into an image, but I am a bit insecure around the terminal!

      11/21/10 @ 7:33 pm

      The bad news is that I don’t think this method works if you have snow leopard 10.6.3 or above.

    12/11/09 @ 6:00 pm

    I am backing up 4 Macs on a 2 TB Time Capsule (Mac Pro, Air, 2 MacBooks). So far so good although after a month, there is already 1.2 TB of the capsule that is already used.

    12/28/09 @ 4:14 am

    I had to turn Time Machine off, because it kept interrupting my work with its error message every five minutes, and that started to seriously bug me. I was fairly upset: Here I bought fancy Apple technology so that I would not have to worry about backups any more, with the end result of no backups at all!

    A couple of weeks have passed, and in the meantime our iMac came up with the message that space was running out on the time capsule. We allowed it to erase older backups as I had done on my MacBook. Just a couple of days ago, upon an impulse, I turned the Time Machine back and, voila!, everything works as though there never had been a problem to start with!

    I don’t understand it, but I am happy so long as things keep working!

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