Dell PowerVault 221S (SCSI) - Manual (Page 13)

A REFERENCE GUIDE FOR OPTIMIZING DELL™ SCSI SOLUTIONS VER A02
PAGE 13 11/17/2005
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
Concatenated 0 1 10 5 50 Cluster
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 2-1 2-7: RAID Level Benefit (Generalized)
Clustering Multi Channel Relative Cost Capacity Scalability
Concatenated drives None None None Excellent Excellent
RAID 0 None Excellent None Excellent None
RAID 1 Moderate Excellent Excellent None None
RAID 10 Excellent Excellent Excellent None Excellent
RAID 5 Moderate Moderate Moderate Moderate Moderate
RAID 50 Moderate Moderate Moderate Moderate Moderate