User`s guide

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Chapter 2
2. Storage Enclosures
The storage enclosure is the basic building block of the SGI InfiniteStorage 4000 mass
storage RAID system. Each storage enclosure provides redundant power and cooling to
its individual components. The storage enclosures also house the I/O components of the
storage system. Chapter 4, “Replacing Enclosure Components” provides information on
removing and replacing customer replaceable units (CRUs).
There are two types of storage enclosures: controller enclosures and expansion
enclosures. As their name implies, controller enclosures contain the RAID controllers for
the storage system. This chapter will focus mainly on describing and defining the
features of the controller and disk expansion enclosures.
The expansion enclosures provide expansion disk drive space without any RAID control
circuitry. The two types of storage enclosures share many of the same components. The
primary difference between controller enclosures and expansion enclosures is the
presence or absence of the RAID controllers.
This chapter describes the components in both the controller and expansion enclosures
in the following sections:
• “A Quick Glance at the Storage Enclosure Hardware” on page 14
• “Overview” on page 15
• “The Disk Drives” on page 17
•“RAID Controllers” on page17
• “Environmental Status Modules (ESMs)” on page 19
• “Power Supply and Fan Modules” on page 20
• “Tray ID Selection” on page 21
• “Link Rate Switch” on page 22
• “SFP Transceivers” on page 22