To determine the best RAID level for your servers, evaluate the read and write loads of all data types and then decide how much you can spend to achieve the performance and availability/reliability that your organization requires. Table 10 describes common RAID levels and their relative performance, reliability, availability, cost, capacity, and energy consumption. Table 10. RAID Trade-Offs Performance Reliability Availability Cost, capacity, and power JBOD Pros: Pros: Pros: Pros: Concurrent Data Single loss Minimum sequential isolation; does not cost. streams to single loss prevent Minimum separate affects one access to disks. disk. other disks. Cons: Cons: Susceptibility Data loss to load after one imbalance. failure. RAID 0 Pros: Pros: (striping) Balanced Minimum load. cost. Potential for Minimum better response Two-disk times, minimum. throughput, Cons: Cons: and Data loss Single loss concurrency. one failure. prevents Single loss access to Cons: affects the entire array. Difficult stripe entire array. unit size choice. RAID 1 Pros: Pros: Pros: (mirroring) Two data Single loss Single loss sources for and often and often every read multiple multiple request (up to losses (in losses (in 100% large large Two-disk performance minimum. ) are do not . survivable. prevent Cons: access. Twice the Cons: cost of Writes must RAID 0 or update all JBOD. mirrors. Up to 2X power
To determine the best RAID level for your servers, evaluate the read and write loads of all data types and then decide how much you can spend to achieve the performance and availability/reliability that your organization requires. Table 10 describes common RAID levels and their relative performance, reliability, availability, cost, capacity, and energy consumption. Table 10. RAID Trade-Offs Performance Reliability Availability Cost, capacity, and power JBOD Pros: Concurrent sequential streams to separate disks. Cons: Susceptibility to load imbalance. Pros: Data isolation; single loss affects one disk. Cons: Data loss after one failure. Pros: Single loss does not prevent access to other disks. Pros: Minimum cost. Minimum RAID 0 (striping) Two-disk minimum. Pros: Balanced load. Potential for better response times, throughput, and concurrency. Cons: Difficult stripe unit size choice. Cons: Data loss one failure. Single loss affects the entire array. Cons: Single loss prevents access to entire array. Pros: Minimum cost. Minimum RAID 1 (mirroring) Two-disk minimum. Pros: Two data sources for every read request (up to 100% performance Cons: Writes must update all mirrors. Pros: Single loss and often multiple losses (in large are survivable. Pros: Single loss and often multiple losses (in large do not prevent access. Cons: Twice the cost of RAID 0 or JBOD. Up to 2X power . )
Perf-tun-srv-R2.docx