White Paper: How To Select The Correct Raid For An Equallogic SAN

By Dell Inc.

This white paper discusses how to select the right RAID policy for your Dell EqualLogic™ storage area network (SAN) arrays. First, each of the RAID types available with EqualLogic arrays is reviewed, in terms of performance, protection and efficiency. Next, we will discuss choosing a RAID policy within the EqualLogic SAN architecture to meet your performance and protection requirements.

EqualLogic PS Series arrays support several different RAID types. Each type has been optimized to maximize its performance within the EqualLogic architecture. Within this architecture, RAID types are selected on an array by array basis, each array being configured with a single RAID policy. By default, this RAID policy focuses on two factors: the RAID type for the array and the number of disks reserved as hot spares. The RAID types available for use within each EqualLogic array are RAID 10, RAID 50, RAID 5, and RAID 6. Depending on the array model, each of these RAID types is implemented with differing numbers of drives dedicated to data, parity, mirrors, and hot spares based on the number of drives available in each model. Table 1 below provides a general definition of each RAID type.