Avago Technologies SAS 9300-4i Host Bus Adapter - Manual (Page 8)

LSI Corporation
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SAS-3 Integrated RAID Solution User Guide
November 2012 Chapter 2: Overview of Integrated RAID Mirrored Volumes
Overview
Chapter 2: Overview of Integrated RAID Mirrored Volumes
This chapter provides an overview of the LSI Integrated RAID features that support the creation of mirrored volumes.
2.1 Overview
As a result of the shift towards network-attached storage (NAS), Internet service providers need a cost-effective,
fault-tolerant solution to protect the operating systems on small form-factor, high-density, rack-mountable servers.
The mirroring features of the LSI Integrated RAID solution provide such protection for the system boot volume, which
safeguards the operating system and other critical information on servers and high-performance workstations. The
Integrated RAID solution supports the following types of mirrored volumes:
 The Integrated Mirroring solution, which provides features of RAID 1
 The Integrated Mirroring + Striping solution, which provides features of RAID 10
 The Integrated Mirroring Enhanced solution, which provides features of RAID 1 Enhanced (RAID 1E)
These three mirroring solutions provide a robust, high-performance, fault-tolerant solution to data storage needs at a
lower cost than a dedicated RAID controller.
Mirrored volumes contain two disks to ten disks to provide fault-tolerant protection for critical data. Mirrored volumes
also support one or two global hot spare drives, with a maximum of 14 drives on each LSI SAS-3 controller.
Each SAS-3 controller can have two global hot spare disks available to automatically replace a failed disk in the one or
two mirrored volumes configured on the controller. The hot spares make the mirrored volumes even more fault
tolerant.
2.2 Integrated Mirroring and Integrated Mirroring Enhanced Features
Integrated Mirroring, Integrated Mirroring + Striping, and Integrated Mirroring Enhanced volumes support the
following features:
 Configurations of one or two mirrored volumes on each LSI SAS-3 controller. Each volume can consist of two
mirrored disks for an Integrated Mirroring volume; three to ten mirrored disks for an Integrated Mirroring
Enhanced volume; or four, six, eight, or ten mirrored disks for an Integrated Mirroring + Striping volume.
 (Optional) Two global hot spare disks per LSI SAS-3 controller to automatically replace failed disks in mirrored
volumes.
 Ability of mirrored volumes to run in optimal mode or in degraded mode if one mirrored disk in an Integrated
Mirroring volume fails or if one or more mirrored disks fail in an Integrated Mirroring + Striping volume or
Integrated Mirroring Enhanced volume.
 Support for hot swapping.
 Support for OCE for RAID 1 volumes. OCE permits you to increase the size of a RAID 1 volume by replacing the
existing disk drives with higher-capacity disk drives. Data is protected during the expansion process, and the
RAID 1 volume remains online.
 Presentation of a single virtual drive to the operating system for each mirrored volume.
NOTE Fourteen drives is the theoretical upper limit for a single LSI SAS-3 controller, although the controller
itself might support fewer than 14 drives. You can also configure one mirrored volume and one Integrated
Striping volume on the same LSI SAS controller.