Ok, I've got 4 1tb hard drives. One will serve as the backup drive so I have three left. Should I use Raid 1 with all three to get maximum protection against data loss or Raid 5 for increased speed or Raid 0+1? Suggestions?
RAID 10 (or 0+1) will provide the best performance/redundacy if you have 4 drives, but requires a minimum of 4 drives. RAID5 will kill your write performance but you can use 3 drives and get N-1 drives worth of usable space.
If you're really concenred about performance and redundacny do RAID 10 with all 4 drives and backup critical stuff somewhere or keep it in two places like your SSD and the RAID 10.
Nowadays, when TB is cheap, RAID protection is no longer necessary. You alredy have a backup drive, so RAID 0 the other ones. If you feel better, use 2 drives for backup and RAID 0 the other 2. In a way, you will be making a RAID 10, lol
leandrodafontoura has an excellent point that backups should be done. It has become a catchphrase here - "RAID is not a substitute for backups."
But any RAID with redundancy (above zero, which is not really RAID, since the R stands for "Redundant") will improve the reliability of your system. A single failed hard drive will not affect the system's usefulness.
My _personal_ choice would be RAID 0+1, using four drives, plus buying at least two more drives for backups. If you only have one backup drive, and you are doing a full backup, and your system crashes, you now have zero backups. I have about eight drives that are used for backups.
Unfortunately, I do not have 4 drives for the RAID setup. I am indignate that one of the four will be for backup and taken off site. So, I have three left. Should I do this? Setup 2 drives at RAID 0 and then one drive as an internal backup? Then I still have one drive for external backup.