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Executive summary
4 Time configuration and synchronization across Management modules, IOMs and iDRACs |
Document ID
Executive summary
In Modern computer networks time synchronization is critical because every aspect of managing, securing
and debugging a network involves determining when events happen. Time synchronization failures between
modules can lead to undesired behavior. Using this feature we can achieve time synchronization within
different modules of MM. We can also achieve time synchronization across different modules like MMs, IOMs,
iDRACs and NTP server.
Introduction
Maintaining same time across different devices manually is not practical. The Management module gives user
the ability to synchronize it’s time to external NTP server through its user interface. Likewise user can decide
to not follow a time source and set the time on MM by himself/herself. User also has the ability to configure
iDRAC to synchronize to the MM. Also SAS IOM by default synchronizes itself to management module with
respect to time.
Why NTP
NTP or similar utility is a necessity in today’s world. Reasons include
• Log file accuracy, auditing and monitoring.
• Network fault diagnosis and recovery
• Access security and authentication systems count on it.
• Distributed computing systems require all the systems to time synchronized
• Legal obligations which require systems to be synchronized
Feature Methodology
On a high-level, this feature is summarized in the following steps
• User can manually set the date/time on the management module using the MM user interface.
• User can configure the management module to synchronize it’s time to external NTP server.
• SAS IOM by default synchronizes to MMs.
• iDRAC can be configured to synchronize to management module using iDRAC user interface.
Management module has internal modules which use either NTP or Chrony for time synchronization. When
there is no external NTP configured, management module uses its own real time clock which keeps ticking
even when the power is off. Different NTP modules talk to each other and decide whom they synchronize to
using stratum numbers. Lower the stratum number, higher is their accuracy to real time.
Feature constraints
• This feature can cause failover when the time moves back due to any of the reasons below