SO here's the question... I have a NAS on my home network with a 1 TB hdd inside it which is being used to store all my media. I have a second hdd slot which I am not currently using, but I want to put in another hdd to have a raid 1 array setup. However, my hard drive that I have inside the NAS is no longer made (just your basic 1 TB hdd sata connection). My question is, can I just put any other hard drive in there and use that to build the raid array? Obviously I would need some of the specs to be the same, size, rpms, but other than that, does it matter? If I am able to use two different ones, would the be a performance loss, and if so, would it be significant? Or do I need to purchase two of the exact same hard drives, and that's the only way to do it? Finally, when I do get the second hard drive, would I be able to just plug it in, and it would build the array (using the application inside my NAS (Dlink 232 or something like that) or would it need to reformat both of my hard drives, and then make the array (effectively wiping all my data unless I backed it up on another hdd)? I know that was kind of a lot, but i just haven't messed with raid before and wanted to be somewhat educated on it before I made any changes to my setup. Thanks guys.

I don't believe in using Raid 1 for backup. If there is ever a problem and bad data gets written, both drives get corrupted. Much better to have a good backup system. It's a little trouble, but safer.

Well, unfortunately that doesn't really answer my question, and I will also have to respectfully disagree. I would definitely bet that the likelihood of my hard drive corrupting itself from writing a bad file is much less likely to happen than a hard drive dying. I've never had a hard drive mess up on me from writing bad data/data being corrupted. I have had a hard drive die on me

Might want to consider buying two new TB sata drives. Drives in a hardware array should match specs or you can experience sync problems. Most raid utilities will allow you to choose which drive is mirrored to which drive. Just make sure you are clear that you are choosing the data drive to mirror to the blank drive. Otherwise you end up with a mirror but no data.