The CALIBRATE command runs raw performance tests on cell disks, enabling you to verify the disk performance before the cell is put online. You must be logged on to the cell as the root user to run CALIBRATE.
Oracle ILOM automatically detects system hardware faults and environmental conditions on the server. If a problem occurs on the server, Oracle ILOM will automatically do the following:
Illuminate the Service Required status indicator (LED) on the server front and back panels.
Identify the faulted component in the Open Problems table.
Record system information about the faulted component or condition in the event log.
References: http://docs.oracle.com/cd/E80920_01/SAGUG/exadata-storage-server-cellcli.htm#SAGUG20617

Note:

Explanation/Reference:

Explanation/Reference:
B: Database Server ILOM plug-in
Monitoring databases and their instances, ASM environments, the Grid Infrastructure, and the host software environment are done by Enterprise Manager in the usual way as these are standard targets. But monitoring the hardware for the database servers requires the ILOM plug-in, as there is no Management Server (MS) on the database servers to receive SNMP traps from the ILOM. The plug-in will receive sensor state and availability data from the ILOM including alerts based on pre-set ILOM thresholds.
C: Exadata Storage Server plug-in extends the monitoring of exadata cells in addition to providing a GUI interface. The plug-in uses an SSH connection to the cellmonitor user on the cells and uses list commands only. This is for interactive monitoring. One may also set thresholds using the plug-in which are distinct from any thresholds set using cellcli utility as the celladmin user. For alerts to be sent to the plug-in, SNMP traps are used as follows:
Cell ILOM alerts are sent to the cell Management Server (MS) via an SNMP trap. The MS then send SNMP notifications onward to the plug-in.
Cell alerts flagged by MS itself, such as cell thresholds being exceeded, or ADR software alerts, are sent to the plug-in using SNMP.
References:
https://dbatrain.wordpress.com/2011/06/
http://docs.oracle.com/cd/E21659_01/html/E21660/z40015671004046509.html

Exadata patches are intended for and include fixes for both the storage servers and Compute servers, and optionally InfiniBand switches.
Patching order
You should patch the Exadata Database Machines in the following sequence References:
https://www.toadworld.com/platforms/oracle/w/wiki/11640.oracle-exadata-patching