Dell Compellent Series 40 - Manual (Page 122)

114 Storage Center 5.5 System Manager User Guide
Disks
Introduction
This chapter describes how to view and manage disks and disk folders. Only Administrators
can manage disks and disk folders. Some commands, indicated in the command
description, are available only when specifically included in Administrative privileges.
System Manager displays disks both physically and logically. Physically, disks are grouped
by the enclosure in which they reside as shown in the Enclosures folder icon.
• Logically, the System Manager groups disks by type, such as a 7K, 10K, 15K, and Solid
State Disk (SSD). Disks types are grouped without regard to IO speed. For example, 7K
disks in a SAS enclosure will be in the same RAID level as 7K drives in an SBOD
enclosure. A disk folder contains both managed and spare drives. Managed drives are
used for data storage; spare drives are held in reserve to automatically replace a drive
if a managed drive fails.
• The ability of Storage Center to optimize data storage is hampered by systems using
Advanced Options. Before using Advance Options, consult with Dell Support Services
so that you understand the impact changes would have on your system.
Storage Types and Storage Classes
A storage type describes a pool of storage with one datapage size (512KB, 2MB, or 4MB)
and either redundancy or no redundancy. Because Data Progression (an automatic
process that moves old data to slower disks) cannot move data between storage types, a
second storage type is a less efficient use of storage. Create a non-standard storage type
only when an application requires a datapage size smaller or larger than the default 2-MB
datapage. Only an Administrator can create a storage type, and only if his or her User
Volume Defaults permit changes.
Storage classes exist within each storage type for which a disk folder has been prepared.
Each storage class represents allocated RAID space within a tier of disks in the disk folder.
For redundant storage types, RAID levels of storage classes within each tier depend on the
redundancy level selected for that tier.
• Single redundant tiers can contain storage classes of RAID 10, RAID 5-5, or RAID 5-9.
• Dual redundant tiers can contain storage classes of RAID 10-Dual Mirror, RAID 6-6, or
RAID 6-10.
• Non-redundant storage types use RAID 0 in all classes, in all tiers.