Developers Guide

11 Understanding RAID with Dell SC Series Storage | 3104-CD-DS
RAID 6 and RAID 10-DM provide the greatest protection, while SSDs have the fastest rebuild rates. 15K
HDDs rebuild faster than 10K or NLSAS. Larger disks of any type are subject to the rate of rebuild to avoid a
dual disk failure. As the number of disks and capacities have increased, RAID 6 or RAID 10-DM have become
increasingly important to ensure overall data protection in storage arrays.
2.2 Space efficiency by RAID level
Each RAID level has capacity efficiencies when compared to the raw capacity available. The general
efficiency of a specified RAID level is easy to compute by taking the disks that are not parity or mirror and
dividing them by the total disks in the set.
RAID level capacity efficiencies in SC Series arrays
2.3 SC Series RAID comparisons
Although all RAID levels provide good performance and data protection, there are some differences. RAID
levels are chosen by the array to accommodate the performance and availability needs of that tier of disks.
Deviations from the standard SC Series allocation of RAID levels should carefully consider the performance
and availability impact on the workload.
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RAID 5-5 RAID 5-9 RAID 6-6 RAID 6-10 RAID 10 RAID 10-DM
RAID 5-5 RAID 5-9 RAID 6-6 RAID 6-10 RAID 10 RAID 10-DM