Spectra T950 - Controller Failover

Chapter 2 — Architecture Overview High-Availability Configurations
November 2016 User Guide—Spectra T950 Library
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Controller Failover
TheBlueScaleControllerFailoverfeatureusestwoRIMsorF‐QIPsthatare
configuredasafailoverpair.RIMsandF‐QIPscanbemixedinafailover
pair;aRIM2canonlybeinafailoverpairwithanotherRIM2.
Onecontrollerinthepairistheprimarycontrollerandtheotheristhe
secondarycontroller.Fromthehostperspective,theprimarycontrolleris
theonlycontrollerpresent.Thesecondarycontrollerisnotvisibletothe
host.
Figure40showsasimplifiedviewofhowthefailoverpairoperates.PortA
oneachcontrollerinthepairisconnectedtothesameFibreChannel
switch.Bothportshavethesameconfiguration,exceptthattheprimary
operatesintargetmodeandthesecondaryisnotactive.
Thetwocontrollersusethelibrary’sinternalcommunicationbusto
monitoreachotherandtomaintainacacheofthelibrary’sinventory
database.
Figure 40 Paired controllers configured to provide failover
redundancy.
Primary Controller
SAN
Secondary Controller
Before failover
Primary Controller
A
B
SAN
Secondary Controller
A
B
After failover
Robotic control path (target port)
Internal communication bus (mirror inventory & partner monitor)