J Lehew

• Aug 25th, 2005

 

Raid 0 - Make several physical hard drives look like one hard drive. No redundancy but very fast. May use for temporary spaces where loss of the files will not result in loss of committed data.  
 
Raid 1- Mirroring. Each hard drive in the drive array has a twin. Each twin has an exact copy of the other twins data so if one hard drive fails, the other is used to pull the data. Raid 1 is half the speed of Raid 0 and the read and write performance are good. 
 
Raid 1/0 - Striped Raid 0, then mirrored Raid 1. Similar to Raid 1. Sometimes faster than Raid 1. Depends on vendor implementation. 
 
Raid 5 - Great for readonly systems. Write performance is 1/3rd that of Raid 1 but Read is same as Raid 1. Raid 5 is great for DW but not good for OLTP. 
 
Hard drives are cheap now so I always recommend Raid 1.