The term RAID stands for (depending on the time frame you learn it) Redundant Array of Independent Disks. This means that more than one disk drive is connected to another in an array fashion. What this also means is that the speed at which one disk can transfer data is multiplied when two are sharing the transfer. Add more disks and multiply the speed advantage.
There are several RAID levels but only a couple of them matter to video capture.
RAID 0 is the fastest setup where transfer speeds are concerned. The speed is accomplished by striping each disk in an array of the same size disks.
Practically, lets consider a 4 disk array and how it works. When a computer writes data to a disk drive it does so in a serial bit fashion. It takes a certain amount of time to write, lets say a 16 bit word. So if we could break up the 16 bit data stream into four 4 bit streams, one to each of the 4 disk drives, it would take theoretically, one fourth of the time to store that 16 bit word.
There is one downside to a RAID 0 array however. If any one of the four disk drives fails, you loose ALL the data from all four disk drives. FAST and LOOSE.
Then there is the SAFER way to go and somewhat slower. RAID 5 is essentially the same setup but uses a safe way to store data but looses some speed advantage because it takes some time to compute the data that allows you to recover from a failed drive.
Finally, the safest way to store data and the most expensive is a RAID 1+0. The RAID 1 is a copy of the master disk and takes a fair amount of time to copy the identical copy of all the data from the master disk. Coupling RAID 0 as the fastest way to copy and RAID 1 as a complete backup virtually insures that no one disk can fail and take all your precious data with it. This also requires twice as many disks as does a RAID 0 array and the hardware to control the data transfers can get expensive.
