Fabric Manager Users Guide, Version 6.1, Revision A - QLogic

1–Overview of the QLogic Fabric Manager Suite
Multiple Fabric Managers in a Fabric
NOTE:
It is important that the configuration of all SMs managing a fabric have the
same configuration. It is especially important that fundamental parameters
such as SubnetPrefix match. It is also recommended that all redundant SMs
are at the same revision level. Failure to follow these recommendations can
result in fabric disruptions when SM failover occurs. Using the Configuration
Consistency Checking feature, the FM can ensure that all redundant FMs
have a comparable configuration. See “FM Configuration Consistency” on
page 1-8 for more information.
Fabric Manager Role Arbitration
Fabric Managers arbitrate for the master role using inband InfiniBand messages
(For example, the SMInfo packet). The Fabric Managers use the value of the SM
Priority parameter (a configurable value in the range 0-15) and then the GUID of
the port on which the Fabric Manager is running (for example, the switch or the
Host Channel Adapter).
The arbitration rules are:
• The Fabric Manager with the highest priority value is master Fabric Manager
• In the case of Fabric Managers with equally high priority value, the lowest
value GUID is the master Fabric Manager
Master Fabric Manager Failover
Failover from master to standby Fabric Manager is essentially seamless. Since
the master and standby Fabric Managers participate in a database
synchronization mechanism, the new master Fabric Manager is equipped with
enough data to continue managing the fabric upon takeover.
The change of master Fabric Managers does not affect data traffic, nor does it
affect communication between fabric nodes and the SM/SA.
Master Preservation – “Sticky” Failover
Multiple Fabric Managers in a fabric can be configured to support “sticky” failover.
Normally when the user configures the Fabric Managers, using the SM Priority
value, to designate the pecking order of master and standby Fabric Managers,
that order always holds true during arbitration. Thus, upon failover of the master, a
standby becomes the new master until the original master is restarted, whereby
the original master reclaims the master role.
1-6 IB0054608-01 B