RAID (Redundant Array of Independent Disks) is a virtual disk technology that combines multiple physical drives into one unit. RAID can create redundancy, improve performance, or do both.
Common types of RAID (there are more, but we only discuss the most commonly used ones):
RAID 0 [Striped disks] = Data is split evenly between two or more disks. The benefit of this type of RAID is having a large single partition (ie. 2x 8TB drives = single 16TB drive) and increasing performance (we must note, the performance increase is for sequential data only and NOT random data). Although it is rare for SSDs to fail, but in the case one of the SSDs in the RAID array fails, all the data would be lost.
RAID 1 [Mirrored disks] = Two or more drives have identical data on them. A single drive failure will not result in data loss. This type of RAID does not offer any performance improvement as the 2nd drive in the RAID arrays is only used for redundancy, as in, a mirror of the first drive's data for the extra peace of mind.
Do we recommend RAID? Well that all depends on your workflow and how you use your computer. For example, for those who use their computer for entertainment such as watching movies, web browsing, light office work, and gaming, would not benefit from RAID because as we mentioned earlier, when you combine two drives together, the random data performance does not increase, only the sequential data gains a boost in performance.
Random data (small files) is what the operating system, programs, games, etc. comprise of, in essence, a lot of small of files when used together make a program function.
Sequential data (large files) is any huge file such as a large database file or a large video file. Due to the size of the file, the user sees it as one file by technically, is is thousands of data clusters stacked up together in a long sequence to make that file, hence the name "sequential data".
With that said, people who work on large files such as 3D content creation, video editors, photo editors, large database files, will see a benefit from a RAID 0 array but we do not recommend it otherwise because NVMe SSDs are super fast nowadays that you will to be able to feel the difference in speed when working with the OS, programs, games, etc. and keep in mind that RAID adds some latency and an increase in boot times (10-15 seconds slower boot time as the BIOS needs to initiate the RAID array before the boot process will start).
Tip: If you choose RAID, it is best to have matching drives for example two Samsung 980 PROs rather than a single 980 PRO and a HIDevolution approved SSD because the RAID Array's speed would always be bottlenecked by the slowest SSD.