Administrator Guide

Storage Center Overview

How Storage Virtualization Works

Storage Center virtualizes storage by grouping disks into pools of storage called Storage Types, which hold small chunks (pages) of data.

Block-level storage is allocated for use by defining volumes and mapping them to servers. The storage type and storage profile associated

with the volume determines how a volume uses storage.

Storage Center combines the following features to provide virtualized storage.

• Disk Management – Sorts disks into disk folders and assigns a storage type based on the disk types.

• Volumes – Allocate storage for use.

• Storage Types – Define a datapage size and redundancy levels for the disk folder.

• Data Progression – Moves pages between tiers and drive types, as well as among multiple RAID levels within the same tier.

• Storage Profiles – Define how data progression moves pages between tiers.

Storage Center Hardware Components

Storage Center consists of one or two controllers, switches, and might include one or more disk enclosures.

Controllers

A Storage Center controller provides the central processing capability for the Storage Center Operating System and managing RAID

storage. A Storage Center is typically configured with a pair of controllers. In a dual-controller Storage Center configuration, the two

controllers must be the same model.

I/O cards in the controller provide communication with disk enclosures and servers that use the storage. Controllers provide two types of

I/O ports:

• Front-end ports – Hosts, servers, or Network Attached Storage (NAS) appliances access storage by connecting to controller Fibre

Channel I/O cards, FCoE I/O cards, or iSCSI I/O through one or more network switches. Some storage systems contain SAS ports

that are designated as front-end ports, which can be connected directly to a server. Ports for front-end connections are located on

the back of the controller, but are configured as front-end ports.

• Back-end ports – Enclosures, which hold the physical drives that provide back-end storage, connect directly to the controller. Fibre

Channel and SAS transports are supported through ports designated as back-end ports. Back-end ports are in their own private

network between the controllers and the drive enclosures.

Switches

Switches provide robust connectivity to servers, allowing for the use of multiple controllers and redundant transport paths. Cabling

between controller I/O cards, switches, and servers is referred to as front-end connectivity.

Enclosures

Enclosures house and control drives that provide storage. Enclosures are connected directly to controller I/O cards. These connections

are referred to as back-end connectivity.

Fibre Channel Switched Bunch of Disks (SBOD) and Serial Advanced Technology Attachment (SATA) enclosures are supported for

existing Storage Centers and for controller migrations only.

Disk Management

Storage Center manages both physical disks and the data movement within the virtual disk pool. Disks are organized physically, logically,

and virtually.

• Physically – Disks are grouped by the enclosure in which they reside, as shown in the Enclosures folder.

• Logically – Disks are grouped by class in disk folders. Storage Center enclosures may contain any combination of disk classes.

38 Storage Center Overview