I have a 2009 MBP 13". Back then a tech guy at Apple helped me remove my CD ROM and helped me install 2 SSD Drives. The two are Vertex 100GB SSD. Supposedly there are two ways to insall them when installing RAID. One is where you only use 100GB (1 SSD) where the other SSD is sort of like a back up and the other way is where one uses both SSD's as one. If one uses both SSD Drives as one then you only have 100GB to use but if you use two then you have close to 200GB to use. I am not much of a tech guy here. Currently it is showing me that I am almost out of space. I would like to know if this is because I have used up the almost 200 GB of space or because I have used up the almost 100GB of space so I know what sized SSD I will need to buy next on my next computer. I enclosed some screenshots below. Many thanks to those offering help.