external hard drive

I have TimeMachine on an external hard drive. When I partitioned the drive I made two partitions in addition to the TM partition. I'd like to make more room for time machine and don't need the contents of the other two "volumes" (which are, I think, also separate partitions). If I erase the volumes will TM recognize that there is now additional space on the external drive and make use of it?

Rocky 63

Yes, Time Machine will utilize whatever space you give it. Be careful removing the other partitions, however, as you can easily also destroy the TM partition. The best way is to use Disk Utility to remove the other partitions and then drag the TM partition boundary to encompass the entire drive. That way you won't lose any of your TM backups.

You should be able to resize the TM partition non destructively with Disk utility

CreativeTechs Tips: Leopard Disk Utility Can Now Resize Partitions.