if all you care about is using the HD's...then forget about RAID (any level)...in my experience it's more hassle than it's worth on a home computer....as long as you've got enough places to plug in all your drives...and they're functional...you'll have no issues...you can have as many as the machine can hold and it will work fineRAID
stands for Redundant Array of Independant (can also stand for inexpensive) Disks....there are 6 standard levels of raid (though you'll only really hear of 5) those being RAID0, RAID1, RAID3, RAID4, RAID5, and RAID6.
RAID0 is the lowest level of RAID and requires at least 2 disks. it is designed to provide "Striping". Striping is the process of breaking data up into chunks and writing each chunk to a seperate disk in the array which effectively increases your immediate storage size. so if you write a 10MB file to a RAID0 array of 10 disks each disk would get 1MB of the complete file (these numbers are made up....the actuall block size depends on configuration of the array). while RAID0 can improve storage speed and percieved storage size...it offers no redundancy...if one drive in the array dies then you lose the entire array because the files on the array are split up between the drives and cannot be rebuilt once one block is lost
RAID1 is the second lowest level of RAID and requires at least 2 disks. it is designed to provide "mirroring". Mirroring is the process of writing the same data to all disks in the array simultaneously. with RAID1 you effectively cut your total storage size (the combined size of both drives) in half because the array is seen as one drive since the data will be written to both drives at the same time. the only purpose for RAID1 is to provide fault tollerance. if one drive in the array dies then you don't lose your data since it was written to both drives.
RAID3 is third and requires at least 3 disks. it is designed to offer striping and "dedicated parity". Striping in this instance is the same as the striping used in RAID0 where the data is broken into chunks and writted to each disk in the array EXCEPT for the last disk in the array, the last disk in the array is for "dedicated parity". Parity in this instance is basically a block of information that can be used to rebuild the information on any of the stripes in the array if one of the disks fails. so in a 3 disk RAID3 array all data will be broken up across two of the disks in stripes and the parity information will be written to the 3rd disk. if disk 2 fails then you can replace that drive and the RAID array will use the information on disk1 and the parity info on disk3 to rebuild disk2's striped information. however with this level you have a bottle neck because every write cycle must not only write to the two striped disks but you must also write to the parity disk. also if the parity drive fails then your array is broken untill the parity can be rebuilt during which time any other drive failure will be catastrophic
RAID4 is basically the same as RAID3 except that it does block level striping instead of byte level striping (look that up it's not worth explaining)
RAID5 is the next level and it requires at least 3 drives. it provides striping with distributed parity. same striping as the other levels and a similar parity as RAID3 except that instead of having a single drive for the parity information it's placed on each drive in a sequence (i.e. drive one get's the first parity info then drive two then drive three etc..). this provides even more redundancy in the array. any single drive in the array can fail and you will not lose your data because the parity information exists on other drives. however this level is still vulnerable to failure if two drives fail at once or if a second drives before the third was in the array was rebuilt
RAID6 is the last level and it requires at least 3 drives. it's basically the same as RAID5 except that it provides striping with dual distributed parity. this means that the parity information is written on two seperate disks at a time and this parity rotates through the array . this gives the array the ability to recover from 2 drive failures since the parity exists on more than one drive at a time.
i don't think you'll need raid at all...i think your best bet would be to use your three drives on their own...use one drive for maybe the OS and applications, one drive for data only, and then the third drive could be used for regularly scheduled backups of the entire system