Dot Hill Systems SANnet II 200 Service Manual download pdf (Page 35)

Chapter 1 Product and Architecture Overview 1-15

1.5.1.2 Active-to-Active Redundant Controller

In active-to-active redundant controller mode, the primary loop serves the I/O traffic

directed to the primary controller, and its pair loop serves the I/O traffic to the

secondary controller. The host-side management software directs I/O traffic to the pair

loop if one of the redundant loops fails.

Since each fibre interface supports only a single loop ID, two HBAs are necessary for

active-to-active redundant controller operation. Using two HBAs in each server

ensures continued operation even when one data path fails.

In active-to-active mode, the connection to each host adapter should be considered a

data path connecting the host to either the primary or the secondary controller. One

adapter should be configured to serve the primary controller and the other adapter to

serve the secondary controller. Each target ID on the host channels should be assigned

either a primary ID or a secondary ID. If one controller fails, the remaining controller

can inherit the ID from its counterpart and activate the standby channel to serve host

I/O.

1.5.1.3 Host Redundant Paths

The controller passively supports redundant fibre loops on the host side, provided that

the host has implemented software support for this feature.

In the unlikely event of controller failure, the standby channels on the remaining

controller become an I/O route serving the host I/O originally directed to the failed

channel on its pair of controllers. Application failover software should be running on

the host computer to control the transfer of I/O from one HBA to another in case either

data path fails.

1.6 Additional Software Tools

The following additional software tools are available:

■ SANscape, a management and monitoring program

■ SANscape Alert, a monitoring utility

■ SANscape CLI, a command-line utility to monitor and manage the array.

Refer to the SANscape Software Installation Guide

for information about installing

these tools.

For additional information, refer to the release notes in the SANnet II 200 array

hardware section at the following web site:

http://www.dothill.com/manuals.

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Dot Hill Systems SANnet II 200 Service Manual Page 35