HP 2000sa RAID 6 with HP Advanced Data Guarding technology: a cost-effective, - Page 4

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. Function/Applications Data is distributed across separate disk drives. Image Editing • Video Production • Pre-Press Applications Mirroring - Identical data stored on two drives, high fault tolerance, very good performance (higher read performance than RAID 0). Accounting • Payroll • Financial Limitations Highly vulnerable to failure. The entire array will fail if one drive fails. 50% of capacity dedicated to fault protection. Doubles the number of drives required. RAID 1+0 Requires a minimum of four drives. RAID 5 Requires a minimum of three drives. Pn represents one set of parity. RAID 6 (ADG) Requires a minimum of four drives. Pn and Qn represent two sets of parity. Implemented as striped, mirrored disks. Database applications requiring high performance and fault tolerance; sacrifices storage efficiency. 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 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. For 24x7 applications that require a higher level of fault tolerance than RAID 5. Potentially risky for large arrays. Can only withstand the loss of one drive without total array failure. Low write performance (improved with battery-backed cache). Lower write performance than other RAID levels. Sequential and burst-write performance can be much improved with battery-backed cache. 4