The simplicity of mixing drive sizes and never powering the unit down is a big plus. Data is always online and accessible. Just follow the rules and procedures from the drobo people when shutting it down.
After spending hours on the net reading various reviews, this is my summary:
Drobo specific advantages:
- Can mix different drive sizes.
- Hot swappable
RAID Box specific advantages:
- Faster write speeds
- Cheaper (initially)
- If box dies, can buy any other companies raid box.
Now which one is cheaper gets unclear if you factor in that someday you will need more space. For sure, the Drobo box is more expensive than a RAID Box initially. However, factor in that you are pretty much stuck with the same size drives and that you have to buy
all new drives when you want to increase your storage space. A person buying RAID is more tempted to spend more cash upfront on bigger drives. Someone buying a Drobo knows that they can incrementally increase their drive size later.