Owner's Manual

Installing and Setting Up CMC 57
Understanding the Redundant CMC Environment
You can install a standby CMC that takes over if your active CMC fails. Your
redundant CMC may be pre-installed or can be added at a later date. It is
important that CMC network is properly cabled to ensure full redundancy or
best performance.
Failovers can occur when you:
• Run the RACADM cmcchangeover command. (See the cmcchangeover
command section in the
RACADM Command Line Reference Guide for
iDRAC7 and CMC.
• Run the RACADM racreset command on the active CMC. (See the
racreset command section in the RACADM Command Line Reference
Guide for iDRAC6 and CMC
.
• Reset the active CMC from Web interface. (See the
Reset CMC option
for
Power Control Operations that is described in "Executing Power
Control Operations on the Chassis" on page 360.)
• Remove the network cable from the active CMC
• Remove the active CMC from the chassis
• Initiate a CMC firmware flash on the active CMC
• Have an active CMC that is no longer functional
NOTE: In the event of a CMC failover, all iDRAC connections and all
active CMC sessions are lost. Users with lost sessions must reconnect to the new
active CMC.
About the Standby CMC
The standby CMC is identical to and is maintained as a mirror of the active
CMC. The active and standby CMCs must both be installed with the same
firmware revision. If the firmware revisions differ, the system reports as
redundancy degraded.
The standby CMC assumes the same settings and properties of the
active CMC. You must maintain the same firmware version on both CMCs,
but you do not need to duplicate configuration settings on the standby CMC.
NOTE: For information about installing a standby CMC, see the Hardware Owner’s
Manual . For instructions on installing CMC firmware on your standby CMC, follow
the instructions in "Installing or Updating CMC Firmware" on page 53.