Using Time Machine on a partitioned HD

It is possible to store regular files on a partition that is being used for TM. I never bother partitioning drives any more. I do suggest you have a target volume that is as least as big as the volume you are backing up because you never want to have to deal with "moving" your TM backup to a larger device at an inopportune time. It's better to do that sort of thing according to plan.

 

Do you have a backup for the external hard drive? Otherwise, using part of it for external storage is unwise. It just puts that data at risk. You should, if possible, store all your data on your main hard drive, and use the external to back all of it up.

It's easy to move to this model using Disk Utility without erasing the already-backed-up portion on the '700' side of the drive. Just open up Disk Utility, on the left choose the name of the external drive (NOT the name of the partition), go to the 'Partitions' tab on the right, and (after you have moved any files on the '300' side back to the main internal drive, of course), and you can delete (not erase; delete) the smaller-sized partition.

After you've done that, there should be three little drag lines in the bottom-right corner of the other partition. You should then be able to enlarge it to the full 1TB size, without having lost any of your backup data.

 

I understand. We all have our limited resources. I don't own a USB flash drive either, and often end up using SD cards to move things around.

But if that's the case, then look no further than r0k's statement; you can still store files on Time Machine partitions just fine.