What are RAID use for? RAID stands for Redundant Array of Inexpensive (or sometimes "Independent") Disks. In EMC Storage, There is several of RAID type but not all the RAID type is suitable for all application.

The SAN Storage administrator has to understand the application requirement and I/O load and usages. Every RAID type serves the different function, hence select the ideal RAID type for the application, always consider the application needs and depending on your environment as well.

 

Why use RAID 1/0
RAID 1/0 – RAID 10 is a stripe across a number of mirrored sets. RAID 1/0 can outperform RAID 5 in workloads that use very small, random, and write-intensive I/O—where more than 30 percent of the workload is random writes. Some examples of random, small I/O workloads are:

RAID 1/0 has the best performance among all the RAID type.

  • Availability for RAID 1/0 is excellent (Mirror).
  • Relatively high due to large number of drives required and low storage efficiency (50%).
  • High performance on read-write.
  • Huge database system.
  • Messaging system, larger exchange server.  
  • Replication database.
  • Application system that use small record and the data are update very frequently. (Inventory system, Account database)
  • If the application is using random write feature, RAID 1/0 should be used for these applications.

Why Use RAID 5?
RAID 5 is
best cost/performance for transaction-oriented networks, very high data protection; Very high performance; Supports multiple simultaneous reads and writes; Can also be optimized for large, sequential application requests. RAID 5 commonly use for serving the medium class media and database system that required write behind performance and read ahead performance. For example, the Operating System and Host Adapter Bus (HBA) are required 64kb transfer rate. RAID 5 is the best choice in this case.

The best fit of RAID 5 for the following application.

  • Small piece of I/O read-write or Random workload with concurrent I/O per gigabyte requirements.
  • High I/O transfer rate which required 30 percent or less of the transaction task. 
  • Commonly use for Sales application, such as generating the static analysis report that pull out from the database.
  • File system, such as photographs, share drive.
  • Exchange server, messaging application.  
  • Media or Video