# Time Machine Saying Not Enough Space on Disk



## dmetzcher (Oct 26, 2008)

I am getting the following error from Time Machine when doing my first backup. The startup disk being backed up, and the TM disk are both the same size.

Macintosh HD: 465.44 (total); *393.99 (free);* 71.45 (free)
Time Machine: *465.44 (total);* 465.29 (free)

The Time Machine error is:


> "This backup is too large for the backup volume. The backup requires 472.7 GB but only 465.3 GB are available."



Why would this be? Other disks are excluded from the backup, and Time Machine is telling me that it needs more space than it actually needs. What should I do?

Thanks.


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## dmetzcher (Oct 26, 2008)

http://discussions.apple.com/thread.jspa?threadID=1625887&tstart=0

Maybe the discussion referenced about explains this?
The TM disk needs about 2x the space of the disk being backed up to get an initial backup going.

I've asked in another thread already (for a different problem with Time Machine) if there is a way to raid two internal 500 GB disks together in my Mac Pro and use them as a TM backup.


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## dmetzcher (Oct 26, 2008)

(I posted the following in another thread where this issue first started. I broke it off and created this thread because it was a different Time Machine issue than the original.)

A tribute to Mac OS X is the fact that I've never used RAID before and was able, in a few minutes, to set up a striped RAID (0) drive using two internal 500 GB drives, tell Time Machine to use the combined 1 TB drive for the backup volume, and get Time Machine backing up my startup volume. 

Not to bash any other operating systems, but I'm not sure how easy this would have been if I were not using a Mac. Easy is the name of the game. It saves me time, frustration, and worry. It also saves those around me from the ranting that would occur if RAIDing weren't easier on a Mac. 

I still think that requiring twice the size of the volume being backed up is a little overkill on Apple's part, but I've had this other internal drive sitting around as a Tiger clone since about a year ago when I upgraded to Leopard. I guess I can safely say that I won't be needing it any longer.

So, we'll see how it goes with my new RAID volume.


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## skip13 (Jun 25, 2010)

Had this same issue when doing a restore 2 nights ago.  Solved it by this. Started time machine, opened options and added to "do not backup" the following file, under Mac HD there is a "users folder" on the bottom,  Click that as the item to exclude.  Have time machine do a backup, after that backup is done, go back into time machine and remove that same folder from the exclude, then do a second backup with time machine.  U will find that time machine takes awhile to do this second backup, but the issues with not enough space do not appear and the backup is a success. Worked for me about 1 hr ago now, as i spent the last 2 days working on the damm thing. Hope this helps  Has got to be something with the sparse-bundle file that is causing this issue with time machine.


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