The Time Machine folder is dynamic and will increase in size, as required, until there is no room left on the disk or the Partition.
A folder, any folder, is only bound by the size of the disk that it is located on. For example, if you have a 1 TB disk, which is empty, and you create a folder on that disk; you can dump anything you like in there up until the folder occupies the entire 1TB.
I suspect that you have partitioned this Buffalo NAS drive and the partition that you chose for Time Machine is quite small and, apparently, full.
You could try copying the TM folder from the partition it is in, to another partition and then choose that as your TM backup location.
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Hello, I recently bought Buffalo NAS drive (2TB) and after lot of hard work i got the Time Machine working for the Mac book PRO. Now the issue is that the time machine Folder is just 100gb large and a single back up took 90gb's now the back is failing saying no disk space. i tried to increase the space by going into disk Utilities. but no luck. its not letting me go more than 100gb. where as the disk space is 2TB. Any help on how i can Increase the Time Machine's Folder size to at least 300gb or 500gb. I am sure CNET will have an Answer was this. Thanks guys... you all ROCK. TArun Singh

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