RAID - What One To Use
Raid is in essence using multiple physical hard drives as a single storage medium. This can be an advantage in a few areas. Raid comes in various forms, the most common is raid0 raid1 and raid5. Each one has its advantages and disadvantages. Below is an expansion on this topic.
In order to use Raid0 you need at minimum 2 physical disks. This raid setup uses all hard drive storage as a single storage medium. If you have 2 500GB hard drives in raid0 then your system will see it as a 1TB hard drive. You will get faster read and write speeds over one normal hard drive because you can read and write to 2 hard drives at once. It will also maximize the space you will get out of raid. However the biggest disadvantage is because there is no redundancy if you have a failure of one of your physical hard drives your whole storage system will fail. But if you need speed and space and dont care about if you get a failure having to retore all your data raid0 is for you.
To use raid1 you need at least 2 physical disks. It is commonly known as raid mirroring as it simply duplicates data on one hard drive to another. In the event of a physical disk failure your data is still available. You do not get any speed boost in either write or read speeds. This is a good solution for a system that does not need a speedy access to data but must have redundancy for failures.
Raid5 is the best of both worlds. It allows better speed for reading and writing information and it allows redundancy in case of drive failure. You need to have at least 3 drives to enable raid5. Data is spread across all drives with a parity data being put on one of them. In case of drive failure the raid system uses this parity information to rebuild the failed drive. If there is a downside to raid 5 it is that you cant utilize all the space of all drives. Unlike raid0 where where your raid storage is the sum of all total storage of the physical drives, raid5 roughly works out to be 75% of the total storage of all the physical drives.