Overview
This section describes how to use the Consistency Checker feature.
The Consistency Checker feature is a tool to assist troubleshooting a switch. It can be used to validate various internal
tables that are distributed between processes and modules. Using such programmatic algorithms remove human error from checking
large and complex tables manually; thereby, quickly confirming the status of the tables and reducing the mean time to resolve
such issues.
The Consistency Checker commands are used to validate software and hardware table states. The result is displayed as pass
or fail. A failure result causes detailed information about the detected inconsistencies to be logged for further investigation.
Each Consistency Checker command may take several minutes to execute depending on the size of the configuration and number
of modules in the switch. The check may fail if any of the tables under assessment change state during the check. Checks do
not differentiate if the failure is due to normal changes, such as zoning changes, port flaps, or genuine errors. Thus, it
is important to verify that a failure was not caused by normal events that occurred during the check. Rerun the failed check
several times over a period of minutes to confirm if the failure is persistent. Persistent failure means that the detailed
failure information does not change. If a persistent failure is found, contact your vendor for further analysis.
Currently, this feature only supports on-demand execution of commands; they are not run automatically by the system.
The Consistency Checker feature supports verification of table consistency for the following features:
Cisco NX-OS Release 8.4(1)
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Access control list (ACL) Tables
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Forwarding information base (FIB) Tables
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Persistent Storage Service (PSS)
ACL Tables
The ACL Consistency Checker verifies the programming consistency between software and hardware for ACL tables including the
following checks:
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Hardware and software synchronization: This validation checks if entries present in the hardware table is same as in the software
table and vice versa. This check flags errors if there is a mismatch in the entries between the two tables or if the error
is present in one of the tables.
-
Hardware and software duplicate entries check: This validation compares entries in the hardware and software tables to find
any duplicate entries and flags them as errors.
Use the
show consistency-checker acl-table-status [module
number] command to run the ACL Consistency Checker. The ACL Consistency Checker is not run automatically or periodically by the system.
FIB Tables
The FIB Consistency Checker verifies the programming consistency between software and hardware entries for Fibre Channel forwarding
and adjacency tables. If there is an inconsistency, the CLI prints the mismatch entries between the hardware and software
entries of the forwarding and adjacency tables.
Use the
show consistency-checker fib-table-status [module
number] command to run the FIB Consistency Checker. The FIB Consistency Checker is not run automatically or periodically by the system.
Persistent Storage Service (PSS)
The PSS Consistency Checker verifies the consistency between run-time and cached configuration data for the following features:
Use the
show consistency-checker pss
command to run the PSS Consistency Checker. The PSS Consistency Checker is not run automatically or periodically by the system.
SAN Analytics
The SAN Analytics Consistency Checker feature identifies inconsistencies in SAN Analytics components such as NPU, modules,
queries, database, analytics ACL entries, and so on.
Use the ShowAnalyticsConsistency command in Cisco MDS NX-OS Release 8.5(1) to run the SAN Analytics Consistency Checker.
This command is a troubleshooting tool that helps to identify inconsistencies in SAN Analytics components such as NPU, modules,
queries, database, port-sampling configuration and so on. Such inconsistencies are abnormal and may lead to issues on the
switch.
This command should be used as part of troubleshooting when SAN Analytics issues are suspected. The specified consistency
check is done at the time the command is issued and the results are displayed. Detailed information about the detected inconsistencies
is displayed to direct further detailed debugging.
![](https://www.cisco.com/content/dam/en/us/td/i/templates/note.gif) Note |
The SAN Analytics Consistency Checker does not work when port sampling or smart zoning is enabled.
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Guidelines and Limitations
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The Consistency Checker feature is supported only on the following hardware:
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Cisco MDS 9132T 32-Gbps 32-Port Fibre Channel Switch
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Cisco MDS 9148T 32-Gbps 48-Port Fibre Channel Switch
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Cisco MDS 9396T 32-Gbps 96-Port Fibre Channel Switch
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Cisco MDS 9700 48-Port 32-Gbps Fibre Channel Switching Module
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Cisco MDS 9700 48-Port 16-Gbps Fibre Channel Switching Module
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If there is a configuration change or a table state change in the environment while a Consistency Checker is running, it is
possible to trigger false positives. In cases where false positives may be a concern, it is recommended to run multiple iterations
of that Consistency Checker.
-
When you execute the
show consistency-checker acl-table-status
command, ensure that there are no background activities that can result in addition, deletion, or modification of existing
ACL TCAM entries. The ACL Consistency Checker may take some time to complete.
-
Before you run the
show consistency-checker acl-table-status
command, ensure that SAN Analytics port sampling is not enabled to prevent false positive results. The SAN Analytics feature
itself does not cause false positive results.
-
When you execute the
show consistency-checker fib-table-status
command, ensure that no routes are added, deleted, or updated while the Consistency Checker is still running. The FIB Consistency
Checker may take some time to complete.
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In Cisco MDS NX-OS Release 8.4(1), the PSS Consistency Checker is supported only on an active supervisor.