Fail-Over Operation; Introduction; Fail-Over Terms; Cabling Considerations For Fail-Over Operation - Overland Storage Neo Series Library Service Manual

F - O
AIL OVER PERATION

Fail-over Operation

Introduction

The Neo Series Library in a multi-module configuration allows one of the slave modules to take over
control of the library as a temporary master in case the primary master module is not operational
(referred to as Fail-over). The fail-over is a manual procedure that needs to be initiated by an operator,
either locally using the Graphical User Interface (GUI), or remotely using Web TLC. Although the intent
is to initiate a fail-over operation when it is determined that the master module is in a hard fault
condition, it can be initiated at any time (for testing purposes, for example). This section describes the
terminology and methodology used to initiate a fail-over operation, and to restore the library to its
normal operating condition.

Fail-Over Terms

Primary Master (Active): a module which is configured as Master, connected to the Primary Elevator
port, and the library is operating normally.
Secondary Master (Standby): a module which is configured as Slave, connected to the Standby
Elevator port, and the library is operating normally.
Secondary Master (Active): a module which is configured as Slave, connected to the Standby Elevator
port, and the library is in a failed-over condition.
Primary Master (Inactive): a module which is configured as Master, connected to the Primary Elevator
port, and the library is in a failed-over condition.
Failed-Over: the condition of a multi-module library, where a designated Slave module will temporarily
act as a Master module in the event of a failure of the primary Master module.

Cabling Considerations for Fail-Over Operation

C-30
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To allow proper Fail-over operation, the SCSI connection to the Primary and Secondary Master
should be daisy-chained. This allows the Secondary Master to assume control of the SCSI Bus if the
Primary Master fails.