Ok. So, I bought a Dell Precision laptop because it has dual drives.
I have one SSD and one HDD installed.
What I want to accomplish is that my SSD backs up to my HDD so if the SSD crashes I have a backup right there and can swap in.
I installed Windows and all my software to my SSD , but did not set the bios for Raid prior to initial setup...
Do I need to start over?
What Raid setting will accomplish this?
Do I need special RAID drives?
The RAID setting would be RAID 1...aka drive mirroring. You may encounter issues with using RAID 1 with an SSD and hard drive, however. At a minimum, you might find that you lose the speed benefit of the SSD as I believe the access speed might be throttled by the slower of the two (i.e. the hard drive). I am not completely sure if this will happen as I have never done a RAID 1 setup with a SSD and hard drive...just two hard drives. One definite this is that if the hard drive is bigger than the SSD, then the size of the SSD will limit the size of the RAID 1 array. RAID 1 arrays will always be limited by the smaller of the two drives. This is why RAID 1 is typically setup with two drives of the same size (i.e. so that you don't waste space on a large drive).
And there is a good chance you might need to start again with this time setting up the RAID before installing Windows, etc. I believe most hardware RAID systems require the RAID mode to be set before storing data. Again, I could be wrong on this. I know this would be true of RAID 0 or any of the higher RAID number versions (i.e. 5, 10, etc) just due to who they work, but not 100% sure with RAID 1. In my experience, I have always setup the RAID 1 array before I put any data on it...and I will note that I have only used RAID 1 arrays for pure data drives...not for boot drives with the OS and programs on it.
As others have noted, you are likely better off doing a more traditional backup scheme rather than RAID 1 if this is your only backup "layer". While I would tend to agree that it would be better to backup to an external drive, I also don't have a huge problem backing up to the internal drive...it is way better than nothing. Personally, my recommendation would be to do one backup to the internal drive and a second to an external drive. Two backups is always better than one! And with this approach, you would always have a backup with you while you are carrying around the laptop without having to carry an external backup drive with you. My other suggestion option would be to setup two SSDs (of the same size) in the laptop in RAID 1 and then put the hard drive into an external enclosure to then backup to in a more traditional way. The downside of this approach is that it is going to be the more expensive option (especially if the SSD is a large SSD).