You can determine the best RAID for your servers by evaluating the read and write loads of the various data types and then deciding how much you are willing to spend to achieve the performance and availability/reliability that your organization requires. Table 8 describes common RAID levels and their relative costs, performance, availability, and reliability. 8. RAID Trade-Offs Performance Reliability Availability Cost and capacity JBOD Pros: Pros: Pros: Pros: Concurrent Data isolation; Single loss does Minimum cost. sequential streams single loss affects not prevent access to separate disks. one disk. to other disks. Cons: Cons: Data loss one Susceptibility to failure. load imbalance. RAID 0 Pros: Pros: (striping) Balanced load. Minimum cost. Potential for better Two-disk minimum. response times, throughput, and concurrency. Cons: Data loss after one Cons: Cons: failure. Single loss Difficult stripe unit Single loss affects prevents access to size choice. entire entire array. RAID 1 Pros: Pros: Pros: Pros: (mirroring) Two data sources Single loss and Single loss and Twice the cost of for every read often multiple multiple losses (in RAID 0 or JBOD. request (up to losses (in large large Two-disk minimum. 100% performance configurations) are configurations) do boost). survivable. not prevent access. Cons: Writes must update all mirrors. RAID 0+1 Pros: Pros: Pros: Pros: (striped Two data sources Single loss and Single loss and Twice the cost of mirrors) for every read multiple losses (in often multiple RAID 0 or JBOD. request (up to large losses (in large Four-disk minimum. 100% performance configurations) are configurations) do boost). survivable. not prevent access. Balanced load. Potential for better response times, throughput, and concurrency. Cons: Writes must update mirrors. Difficult stripe unit size choice.
You can determine the best RAID for your servers by evaluating the read and write loads of the various data types and then deciding how much you are willing to spend to achieve the performance and availability/reliability that your organization requires. Table 8 describes common RAID levels and their relative costs, performance, availability, and reliability. 8. RAID Trade-Offs Performance Reliability Availability Cost and capacity JBOD Pros: Concurrent sequential streams to separate disks. Cons: Susceptibility to load imbalance. Pros: Data isolation; single loss affects one disk. Cons: Data loss one failure. Pros: Single loss does not prevent access to other disks. Pros: Minimum cost. RAID 0 (striping) Pros: Balanced load. Potential for better response times, throughput, and concurrency. Cons: Difficult stripe unit size choice. Cons: Data loss after one failure. Single loss affects entire Cons: Single loss prevents access to entire array. Pros: Minimum cost. Two-disk minimum. RAID 1 (mirroring) Pros: Two data sources for every read request (up to 100% performance boost). Cons: Writes must update all mirrors. Pros: Single loss and often multiple losses (in large configurations) are survivable. Pros: Single loss and multiple losses (in large configurations) do not prevent access. Pros: Twice the cost of RAID 0 or JBOD. Two-disk minimum. RAID 0+1 (striped mirrors) Pros: Two data sources for every read request (up to 100% performance boost). Balanced load. Potential for better response times, throughput, and concurrency. Cons: Writes must update mirrors. Difficult stripe unit size choice. Pros: Single loss and multiple losses (in large configurations) are survivable. Pros: Single loss and often multiple losses (in large configurations) do not prevent access. Pros: Twice the cost of RAID 0 or JBOD. Four-disk minimum.
WS08PerformanceTuningGuide_En.docx