Dell PowerVault 221S Optimizing Dell SCSI Solutions - Page 13

A REFERENCE GUIDE FOR OPTIMIZING DELL™ SCSI SOLUTIONS VER A02 Additional configuration factors Hot Spares Hot Spare functionality provides extra security availability and redundancy by replacing a failed drive, allowing the rebuild of the degraded array to begin immediately. Both the Adaptec and LSI based PERC controllers' support this feature, but a simple SCSI controller would not. See the controller user's guide for details and limitations. Use of Hot Spares is recommended whenever possible. Clustering Considerations In a cluster environment the cache being disabled on the controller poses a significant performance impact to RAID 5 and RAID 50 configurations. If the system is to be clustered RAID 10 is the optimal RAID level. • Table 2-17: Cluster Solution Vs RAID Levels RAID Level Cluster Concatenated 0 1 10 5 50 Solutions Not Recommended Recommended Possible Considerations for Optimal RAID Performance The PowerVault™ 22xS is capable of offering increased performance by allowing multiple channels to connect to the storage enclosure. This ability can increase the performance of most configurations by allowing a multi channel RAID controller to increase the bandwidth of the SCSI bus. For more information see Table 4-2: PV22xS Configuration Topologies vs RAID Level Performance. • Table 2-12-7: RAID Level Benefit (Generalized) Concatenated drives RAID 0 RAID 1 RAID 10 RAID 5 RAID 50 Clustering None None Moderate Excellent Moderate Moderate Multi Channel None Excellent Excellent Excellent Moderate Moderate Relative Cost None None Excellent Excellent Moderate Moderate Capacity Excellent Excellent None None Moderate Moderate Scalability Excellent None None Excellent Moderate Moderate PAGE 13 11/17/2005