an external enclosure for 2 drives may or may NOT have a built in raid controller.
You basically have 3 choices.
1) It is a single enclosure but is seen as the 2 disks it really is. ex: D: and E: or whatever you want to call them.
The next 2 options require an enclosure with some kind of Raid Controller.
2) JBODS (Just a bunch of disks). In this case you get the full capacity of 1 tb, but it looks like a single large logical disk.
3) RAID 1, or Mirroring. Your stuff is written to both drives simultaniously. Your real capacity is 1/2 the gross capacity.
Do you want redundancy? If so, get a Raid system.
I strongly suggest you do not ever configure a system as jbods. In a jbods scenario, if 1 of the 2 drives fails, you have lost all your data on BOTH drives. so you are twice as likely to lose data as if you just keep the drives separate. And you lose all the data rather than just 1/2 of it.
With all of that said. If you do not have a decent backup plan now. I suggest you forget about the NAS and just buy 2 firewire 800 or USB enclosures. (they are ridiculously cheap) Put 1 drive in each and alternate your backups.
The key for any REAL backup is that it is NOT NOT NOT online. I feel sorry for all the fools who use nas for backup. When a power surge takes out their PCs and Macs, it will also take out their online backup system. And then there are viruses. The kind that wipe out all your disks, including the NAS ones you are attached to.
Backup is offline, period. Use them for backup if you dont have anything at this point.
Don
p.s. for those who are smugly thinking that their pc is on a surge strip or ups, I have a question. Is EVERY networked device so protected? Evry PC? Every Mac? Every router, switch, cable modem?
Is there a surge protector on your phone line coming into the house?? I've seen PCs taken out via a surge over the ethernet cable. Do yourself a favor. Unplug your backup systems.
Here is what I do. I use a NAS system for backup, but it is offline other than when i am backing up. It resides inside a 1100lb firesafe. the ethernet and power cables come out of the safe to a wall outlet with power and an rj45 jack to my switch. When I do a backup, I plug in the NAS. When i am done, I unplug power and ethernet. The unit is electrically isolated and physically protected against theft or fire. I may sound like a bit of a wacko. But if I think about how long it took to rip all those CDs and all the pictures I've taken over the last 6 or so years. It is pretty reasonable.
