Not a Police RAID

RAID stands for Redundant Array of Inexpensive Disks. Which is basically using multiple hard drives for fast storage and transfer of data.This often improves data reliability, volume size, and maybe some performance improvements as well.

There are many types of RAID configurations. Which is how it is setup to work, meaning one RAID is not necessarily the same as another RAID setup. The first one is called RAID 0 (sometimes referred to as Striped) which splits the data into fragments on different disks to give more performance boost to the user. Although, this is faster, but it doesn't use error checking. So if that particular drive fails... all data on that drive is lost.

RAID 1 is different. The information that is written on disk 1 is the same information that is automatically written to disk two, assuming you only have two disks. This can be done with more than two disk drives. This is often referred to as mirroring. As the exact same data is mirrored on the second drive. This provides a strong backup if one drive fails.

RAID 2 is like the Holy Grail of RAID is uses a controller in charge of two disks to write data in exactly the same rate as the other disk. This is not really in use today.

Next, RAID 3 uses a combination of mirroring and striping, per say. It isn't an exact combination of the two, but more like a mesh. RAID 3 utilizes four hard drives which three of them are used in a striping fashion then the forth drive is a combination of the three combined. This setup uses byte level striping which spreads that data across the drives like in RAID 0. That fourth disk is the parity disk which is a collaboration of the other disks data and checks for errors using parity, even and odd based.

RAID 4 also uses a parity disk (the collaboration disk from above), but it is different in that it uses block level striping. This is much like RAID 3 minus the type of striping. The striping is just done on a higher level. RAID 5 uses a parity disk that is split between the drives. Meaning there is no single dedicated parity disk. The "parity disk" is actually spread out with in the disk drives. But works the same way. The disk works in a block level parity and if one block fails then the combination of the data is formed back together with the remaining blocks.

RAID 6 is overall the same as RAID 5 but utilizes two "parity drives", although, still split up between the multiple drives. Note this setup will require one more disk drive than assumed needed for the same data volume as if needed for RAID 5.

There are also several other types of RAID which all need to use a controller to manage the transfer and reformation of data. Those other examples are not standard and I will not mention them in this text. Two types are software and hardware. The software RAID will use your operating system to coordinate the transfer and allocation of data. The hardware type will use the software inside the hardware to do the same thing. Overall, hardware RAID is more beneficial because of free usage that isn't boggled down.

One thing to keep in mind is that the smallest drive you use that is all you can use for mirroring, and for striping it is two times your smallest drive. So for example you have a one GB drive and an 8 GB drive you want to set up in RAID 1 all the data you can put on is one GB.