Mac – Time Machine says not enough space but there is plenty of space

backuptime-machine

I'm not sure what happened but I used to be able to backup to a drive shared with a networked Mac Mini using OSX server. Now all of a sudden it says there is not enough space.

So I reformatted the drive (12TB) and restarted the whole thing. However Time Machine now tell me there is not enough space. It says:

The backup disk needs 5.35 TB for the backup but only 499.49 GB are available.

I'm not sure why only 499GB is available.

Best Answer

I've run into this before when using networked backup, also said something like 497GiB were free when actually 4TiB were free. Seems this is caused by TM not creating a large enough sparsebundle for the initial backup. I found a workaround that at least worked for me (El Capitan) and submitted a bug report to Apple.

Workaround: You should notice that the sparsebundle on the OS X server has only ~499GiB as its capacity. Manually enlarge it by running this command on the server: sudo hdiutil resize -size [number of gigabytes]g [path to sparsebundle], e.g. sudo hdiutil resize -size 10000g /Volumes/Backups/mybackup.sparsebundle. Make it as large as you need. Retry your backup.

Edit: You may also have to resize the sparsebundle's partition in Disk Utility. I didn't have to do this, but maybe that's because my backup wasn't encrypted. For instructions, see the first (not accepted) answer here: Increase size of sparsebundle for TimeMachine

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MacOS – How to manually delete old backups to free space for Time Machine

Be careful with sudo and making sure you pick the correct Mac's files since there is no undo or confirmation of the following command:

sudo tmutil delete /Volumes/drive_name/Backups.backupdb/old_mac_name

The sudo command needs your password (and it won't echo to the screen, so just type it and pause to be sure you're dating the correct files before pressing enter). If you want to be safer, you can pick one snapshot to delete first to be sure the command works as intended. This is nice since it could take hours to clean up some larger backup sets and you want to leave the Mac confident it's deleting the correct information store.

You can use the tmutil tool to delete backups one by one.

sudo tmutil delete /Volumes/drive_name/Backups.backupdb/mac_name/YYYY-MM-DD-hhmmss

Since tmutil was introduced with Lion, this will not work on earlier OS versions.

If you want to get the current directory of backups (there can be multiple destinations defined and only one will be "current")

sudo tmutil machinedirectory

MacOS – Time Machine not fully encrypted. Is it safe to use

Ideally, the CoreStorage encryption should continue after you reconnect the Time Machine drive after your format. But practically, it's a risk that you shouldn't take unless you have other backups to recover from (like a SuperDuper! or Carbon Copy Cloner bootable clone).

Best Answer

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