HP LC2000r HP NetRAID 1M/2M Installation & Configuration - Page 27

Chapter 2 RAID Overview ♦ With the HP NetRAID-2M adapter, you can span up to eight RAID 5 arrays, although the total number of disks in the RAID 50 logical drive is limited by the number of disks that can be attached to the two SCSI channels. For example, if two Rack Storage/12 enclosures are used, the maximum number of disks in a RAID 50 logical drive is 24. RAID 50 gives good performance if you have a high volume of small, random transfers. RAID 50 Disadvantages • Capacity expansion is an offline operation only. • Performance is slower than RAID 0 or RAID 10. RAID 50 Summary • Choose RAID 50 if you need a large logical drive size, and cost, availability, and performance are equally important. RAID 50 performs best for I/Ointensive, high read/write ratio applications such as transaction processing. Table 2-1. RAID Level Summary for RAID Levels 0 to 5 RAID Level Also Known As Fault Tolerance Redundancy Type Hot Spare Option Disks Required Usable Capacity Capacity Reduction Read Performance Random Write Performance Sequential Write Performance Typical Usage RAID 0 striping no none no one or more greatest none fast (depends on number of disks) fastest fastest Rapid reads and writes with no need for fault tolerance RAID 1 mirroring yes duplicate yes two least 50% intermediate intermediate intermediate Mostly small random writes with fault tolerance RAID 5 striping with distributed parity yes parity yes three or more intermediate capacity of one disk fast slow slowest Mostly small, random transfers with fault tolerance 19