Users Guide

For more information about trace logs and conguration options, refer to S-Series Debugging and Diagnostics.
Core Dumps
A core dump is the contents of RAM a program uses at the time of a software exception and is used to identify the cause of the exception.
There are two types of core dumps: application and kernel.
• Application core dump is the contents of the memory allocated to a failed application at the time of an exception.
• Kernel core dump is the central component of an operating system that manages system processors and memory allocation and makes
these facilities available to applications. A kernel core dump is the contents of the memory in use by the kernel at the time of an
exception.
System Log
Event messages provide system administrators diagnostics and auditing information.
Dell Networking OS sends event messages to the internal buer, all terminal lines, the console, and optionally to a syslog server. For more
information about event messages and congurable options, refer to Management.
Hot-Lock Behavior
Dell Networking OS hot-lock features allow you to append and delete their corresponding content addressable memory (CAM) entries
dynamically without disrupting trac. Existing entries are simply shued to accommodate new entries.
Hot-Lock IP ACLs allows you to append rules to and delete rules from an access control list (ACL) that is already written to CAM. This
behavior is enabled by default and is available for both standard and extended ACLs on ingress and egress. For information about
conguring ACLs, refer to Access Control Lists (ACLs).
Process Restartability
Process restartability is an extension to the Dell Networking OS high availability system component that enables application processes and
system protocol tasks to be restarted.
This extension increases system reliability and uptime by attempting to restart the crashed process on primary RPM before executing the
failover procedure as a last resort.
Currently, if a software exception occurs, Dell Networking OS executes a failover procedure. In a single-RPM system, the system generates
a coredump and reboots; in a dual-RPM system, the system generates a coredump and fails over to the standby RPM.
With a system reload, the system must read and apply the entire startup-cong le, which might take some time if the startup-cong is
large. Restarting a process saves time because only a portion of the conguration related to the crashed process is read and reapplied.
For a dual-RPMs system, restarting a process also precludes launching the failover process on the primary and standby RPMs. Recovery is
attempted rst locally on the primary RPM, which involves less CPU overhead, increasing the systems availability for other activities.
However, in both single and dual-RPM systems, even when you congure process restart, the coredump portion of failover is still executed.
The processes that you can restart fall under three categories:
• Interface-related processes — TACACS+, RADIUS, CLI, and SSH, and so on.
• Protocol tasks — OSPF, RIP, and ACL, and so on. Process restart is not currently available for protocol tasks; the failover procedure is
executed immediately after software exception.
• Line card processes — IPC, Event Log Agent, Line Card Manager, and so on. Process restart is not currently available for line card
processes; the failover procedure is executed immediately after software exception.
High Availability (HA)
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