Reviewing Enclosure Location Guidelines - IBM SAN Volume Controller 2145 Quick Start Manual

Table 1. Hardware locations of enclosures and other devices (continued)
Rack unit
EIA 5
EIA 4
EIA 3
EIA 2
EIA 1

Reviewing enclosure location guidelines

Consult these guidelines when you plan the location of a control enclosure and the expansion enclosures
that are to be attached to it.
Each control enclosure contains two node canisters, forming an I/O group. The guidelines apply on an I/O
group by I/O group basis.
Plan for one of these installations:
• Control enclosure only
The control enclosure requires two standard rack units of space in a rack. If you plan to add expansion
enclosures in the future, follow the guidelines for a control enclosure plus one or more expansion
enclosures.
• Control enclosure plus one or more expansion enclosures
– Each control enclosure requires two standard rack units of space in a rack.
Important: The control enclosure must have a 12 Gb SAS adapter installed (feature code AHBA) to
use expansion enclosures, as the SAS enclosures are connected to port 1 and port 3 of the adapter.
– Position the control enclosure in the center of the rack to make cabling easier. Balance the number of
expansion enclosures above and below the control enclosure
– Position the enclosures together. Avoid adding other equipment between enclosures.
– Position the enclosures in the rack so that you can easily view them and access them for servicing.
This action also allows the rack to remain stable and allows two or more people to install and remove
the enclosures.
– A maximal configuration spans multiple racks. If multiple racks are required, locate the racks next to
one another.
– Attach no more than 10 2U or 4 5U expansion enclosures to port 1 and port 3 of the control
enclosure.
Your system supports specific combinations of SAS expansion enclosures, based on the capacity of
each of the enclosures.
To limit contention for bandwidth on a chain of SAS enclosures, a maximum of four high-density
expansion enclosures ( 2147-92F ) can be installed in the chain. High-density enclosures and
standard-density enclosures ( 2145-12F and 2145-24F ) can be mixed within a chain, based on the
following rules:
- A chain is allowed to have expansions with a total "weight" of 10.
- Standard-density enclosures are assigned a weight of 1.
- A high-density expansion enclosure is assigned a weight of 2.5.
The following table shows examples of expansion enclosure configurations based on these
guidelines:
Component
Chapter 1. Planning 3