OK so I put in an SSD and have my original 250gb drive in an external case. I want to use it for time machine and backing up my photos. My question is how many partitions should I use and how much space should I allocate? Also since the external drive will not be hooked up all the time how will that affect time machine? I want to set it up but do it right the first time. A few questions I know and some are very general... but any in-site will be greatly appreciated.