These days many of us have home networks with multiple computers with growing collections of media files. And with that comes the idea of adding storage. Of course, you can add larger hard drives to your computers, but there are advantages to having Network-Attached Storage (NAS). One advantage is that it lets you make use of a computer that might otherwise be too underpowered for desktop use. Storing and serving files is not computationally intensive, and you can often do quite well with a computer that has a Pentium3 processor and 512MB of RAM. Another advantage is that you can configure this to stream files without interference from your other computing tasks.
One option is to use FreeNAS, a specialized OS installation based on FreeBSD. This is not too difficult to install, and comes with a lot of features. Because it is expressly designed as a storage server, it comes with support for Samba, FTP, NFS, RSYNC (for backups), software Raid (0,1,5), and disk encryption.
Another option, which trades money for time and effort, is to buy an NAS box. There are many of these on the market, and recently Maximum PC Magazine did a review of some of the better ones. Most of these options, like the FreeNAS solution, make use of something called RAID, which stands for Redundant Array of Inexpensive Disks. The idea of RAID is to built in some redundancy by making one drive a parity drive. The idea is that you can have at least three drives (you could have more), and one of those drives is devoted to keeping parity information. Suppose you have a drive keeping even parity information. On Drive 1, you have a 1 in the first position, on Drive 2 you also have a 1 in the first position. If you add those up, it becomes a zero, and that is what you would store in the first position of the parity drive. It might look like this:
|Position||Position 1||Position 2||Position 3||Position 4|
|Even Parity Drive||1||1||0||0|
Now, RAID with Parity has the advantage of letting you replace any one drive without losing your data. For example, if Drive 2 were to stop working all of a sudden, you could reconstruct the contents of that drive by looking at the remaining drives. You could look at Drive 1 and see a 0 in the first position, look at the parity drive and see a 1 in the first position, and the only way that could happen is if Drive 2 had a 1 in the first position. So you can put in new disk and rebuild Drive 2 from the information you have.
There are a couple of things that are not so good about this, though. The first is that while you have some protection with RAID, it is not supposed to be a backup solution, and you should never use it in place of backup. If two or more drives go out, you have lost all of your data, and there are lots of ways that can happen (fire, flood, lightning strike, theft, etc.). The other thing that limits RAID is that the capacity of the system is defined by the smallest drive you have. If you had a 500GB drive, a 400GB drive, and a 100GB drive in a RAID array, each drive can only contribute 100GB to the array. So one drive is used for parity, the other two for data, and you can store 200GB of data in an array that had 5 times that in available storage.
One company found a way around that. Data Robotics, Inc. created a device called the Drobo, which lets you use drives of various capacities without wasting all of that space. They must be moving parity data around on various drives in some way to do this, but I don’t know the details. I suspect they are proprietary in any case. (See what they say here.) I can say that everyone who has one loves it, as far as I can tell. But it is pricey. A four-bay chassis, with no drives installed, is at least $400.
But there is another solution. A company called Lime Tech has created a product called Unraid, that does many of the same things Drobo does, but as a software-only solution. A Basic package, which supports up to three drives, is free. Basic Plus supports up to 6 drives for $69, and Basic Pro supports up to 16 drives for $119. You provide the hardware, including drives. So this is not a free solution, but in many respects cheaper than Drobo, so it may be the right solution for you. You can see more discussion and a video of an installation from Category 5 TV.