Raid

Played with some raid controler stuff today sorta going in blind can someone give me some basics on its purpose?

 

RAID was conceived to offer more reliable fault tolerant disk storage. In most RAID arrays, (except RAID0, a special case), you can survive a drive failure with no loss of data. RAID1, commonly called mirroring, has two drives that both maintain identical information. RAID5, the other common scheme, has three or more disks with data and parity striped across them. There is enough parity data to continue if any single disk fails. Another advantage of RAID5 is that you'll normally get a performance increase over a single hard disk, since you're reading/writing multiple disks in parallel, so less data has to be read from each drive.

You could write a book on RAID and not touch on all the issues, that's just the nickel tour.