• 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
logged off. Users with logged-off sessions must reconnect to the new active CMC.
About 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 the CMCs, but you do not have to duplicate configuration settings on the
standby CMC.
NOTE: For information about installing a CMC, see the VRTX Owner’s Manual. For instructions about
installing CMC firmware on your standby CMC, see Updating Firmware.
CMC Failsafe Mode
The PowerEdge VRTX enclosure enables the fail-safe mode to protect the servers and I/O module from
not functioning. The fail-safe mode is enabled when a CMC is not in control of the chassis. During the
CMC failover period, or during a single CMC management loss:
• You cannot turn on the newly installed servers.
• You cannot remotely access existing servers.
• Server performance reduces to limit power consumption until management of the CMC is restored.
The following are some of the conditions that can result in CMC management loss:
• CMC removal — Chassis management resumes after replacing CMC, or after failover to standby CMC.
• CMC network cable removal or network connection loss — Chassis management resumes after the
chassis fails over to the standby CMC. Network failover is only enabled in redundant CMC mode.
• CMC reset — Chassis management resumes after CMC reboots or chassis fails over to the standby
CMC.
• CMC failover command issued — Chassis management resumes after the chassis fails over to the
standby CMC.
• CMC firmware update — Chassis management resumes after CMC reboots or chassis fails over to the
standby CMC. It is recommended that you update the standby CMC first so that there is only one
failover event.
• CMC error detection and correction — Chassis management resumes after CMC resets or chassis fails
over to the standby CMC.
NOTE: You can configure the enclosure either with a single CMC or with redundant CMCs. In
redundant CMC configurations, if the primary CMC loses communication with the enclosure or
the management network, the standby CMC takes over the chassis management.
Active CMC Election Process
There is no difference between the two CMC slots; that is, slot does not indictate precedence. Instead,
CMC that is installed or started first, assumes the role of an active CMC. If AC power is applied with two
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