Developers Guide

15 Understanding RAID with Dell SC Series Storage | 3104-CD-DS
4 SC Series RAID level use
By default, an SC Series array groups all disks in a single disk folder. This disk folder contains all the various
speeds and capacities of disks. Redundancy levels can be configured for each tier of disk. Tier 1 disks are the
fastest disks in SC Series storage, while other disks are grouped according to their speed in the other two
available tiers (Tier 2 and Tier 3). RAID is allocated within a tier across all of the disks. However, unlike other
storage architectures the SC Series, tiers of disks may have multiple RAID configurations simultaneously.
When a volume is created, it is allocated across all of the tiers and RAID levels.
Tier 1 is typically configured with RAID 10 and RAID 5, and Tier 3 typically includes large disks that are
automatically configured for dual redundancy or RAID 10-DM and RAID 6.
Figure 4 shows a typical disk folder with the different RAID levels and their tier associations.
Tier 1 and Tier 3 with various RAID levels
The disk folder is labeled Assigned by default and the storage type is Assigned – Redundant – 2MB, which
refers to a redundant storage type allocated with 2MB data pages.
4.1 SC Series disk and RAID layout
Within a disk folder, the SC Series automatically distributes the data and parity or mirrors to avoid hot spots
across the available disks. Each tier automatically configures the appropriate RAID level, if a particular RAID
level is not used the SC Series system removes the unused extents that make up that RAID set so that space
is maximized in that tier.