Originally Posted by BizarroTerl
You're right about Freenas - you cannot add a drive to the array. You add "sets" of drives. IE to add 3GB you would need 2 - 3GB drives. It also needs more hardware capability that unraid/flexraid/mdadm. IIRC, they recommend 8GB of RAM as a minimum.
If you are using FreeNAS' version of ZFS, then yes, you need to add drives in sets (called vdevs)... but there is a good reason to do so. If you are using mirroring, then you'd obviously want to add disks in pairs. If you want to use RAIDz, then you need to add disks in sets of three at a minimum. With only 3 drives like the OP posted... don't bother with ZFS. You can use UDF in FreeNAS instead. It will do up to RAID 3 in UDF, which is fine for media storage. RAID 3 is similar to how FlexRAID works.
Now as for memory, the recommended minimum is 4GB. But the more memory you throw at ZFS, the better it will cache your data transfers. It's just that if you want to use ZFS, then it will use all the memory you have to cache... so more is better. Like I said above though, don't use ZFS with only 3 drives. It shines with big data and good hardware.
What is best for you really depends on what you want to accomplish. If you want to use it as a server (run other apps as well as nas function) then something like flexraid is a good option. If you're going to use it as a nas only system then unraid is a good option.
FreeNAS has tons of functionality. I don't see the advantage here. If you plan on using FlexRAID, then you will need to purchase a Windows license... otherwise, you are using Linux, which takes you back to BSD functionality (FreeNAS is based on BSD.) There is a large userbase with FreeNAS and there are plenty of plugins for NAS/Server functionality.
All that being said... FlexRAID is a good choice for the OP, with his small hard drive total. I just don't think knocking FreeNAS is the right approach here. It's free, expandable, very functional, and has a large userbase to help out with issues.