HP 166207-B21 Compaq RAID Advanced Data Guarding: A Cost-effective, Fault-tole - Page 4

TC020604TB TECHNOLOGY BRIEF Compaq RAID Advanced Data Guarding ... Table 1. Summary of RAID Technologies for Large Arrays RAID LEVELS RAID 0 Requires a minimum of one drive. RAID 1 Requires a minimum of two drives. RAID 1+0 Requires a minimum of four drives. RAID 5 Requires a minimum of three drives. Pn represents one set of parity. Compaq RAID Advanced Data Guarding Requires a minimum of four drives. Pn and Qn represent two sets of parity. Function/Applications Files are split up and striped across separate disk drives. Image Editing • Video Production • Pre-Press Applications Limitations No fault tolerance and highly vulnerable to failure. The entire array will fail if one drive fails. Mirroring - Identical data stored on two drives, high fault tolerance, very good performance. Accounting • Payroll • Financial Implemented as a stripe of mirrored disks. Database applications requiring high performance and fault tolerance, but willing to sacrifice storage efficiency. Requires 50% of capacity to be dedicated to fault protection. Doubles the number of drives required. One set of parity data is distributed across all drives. Protects against the failure of any one drive in an array. Transaction processing • File and application servers • ERP • Internet and Intranet servers Relatively low fault tolerance. It can only withstand the loss of one drive without total array failure so it is highly risky for large arrays. Two sets of parity data are distributed across all drives. Protects against the failure of two drives in an array. Provides higher fault tolerance than RAID 5. Lower write performance than other RAID methods. For 24x7 applications that require a higher level of fault tolerance than RAID 5. 4