Configuration Logger Persistency
First Published: June 19, 2006
Last Updated: May 2, 2008
The Configuration Logger Persistency feature increases the operational robustness of Cisco IOS configuration and provisioning actions by implementing a "quick-save" functionality. When the Configuration Logger Persistency feature is configured, Cisco IOS software saves just the commands entered since the last startup-config file was generated, rather than saving the entire startup configuration.
Finding Feature Information in This Module
Your Cisco IOS software release may not support all of the features documented in this module. For the latest feature information and caveats, see the release notes for your platform and software release. To reach links to specific feature documentation in this module and to see a list of the releases in which each feature is supported, use the "Feature Information for Configuration Logger Persistency" section.
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Contents
•Prerequisites for Configuration Logger Persistency
•Information About Configuration Logger Persistency
•How to Configure the Configuration Logger Persistency Feature
•Configuration Examples for the Configuration Logger Persistency Feature
•Additional References
•Command Reference
•Feature Information for Configuration Logger Persistency
Prerequisites for Configuration Logger Persistency
To enable the Configuration Logger Persistency feature, you must have disk0: configured and an external flash card inserted on the router.
To achieve optimum results from the Configuration Logger Persistency feature, you must have Cisco IOS Release 12.2(33)SRA, Release 12.4(11)T, Release 12.2(33)SXH, or Release 12.2(33)SB installed on your system.
Information About Configuration Logger Persistency
To understand and use the Configuration Logger Persistency feature, you should be familiar with the following concepts:
•Use of Configuration Logger Persistency to Save Configuration Files
•Persisted Commands
Use of Configuration Logger Persistency to Save Configuration Files
Cisco IOS software uses the startup-config file to save router configuration commands across reloads. This single file contains all the commands that need to be applied when the router reboots. The startup-config file gets updated every time a write memory command or copy url startup-config command is entered. As the size of the running-config file grows, the time to save the startup-config file to the NVRAM file system increases as well. Startup-config files can be 1 MB and larger. For files of this size, making a single-line change to the startup-config file requires that the entire startup-config file is saved again even though most of the configuration has not changed.
The Configuration Logger Persistency feature implements a "quick-save" functionality. The aim is to provide a "configuration save" mechanism where the time to save changes from the startup-config file is proportional to the size of the incremental changes (with respect to the startup-config file) that need to be saved.
The Cisco IOS configuration logger logs all changes that are manually entered at the command-line prompt. This feature also notifies the registered clients when changes to the log occur. The contents of the configuration log are stored in the run-time memory—the contents of the log are not persisted after reboots.
The Configuration Logger Persistency feature provides a mechanism to persist the configuration commands entered by users across reloads. Only the commands entered at the command-line interface (CLI) (that is, the commands entered in configuration mode) are persisted across reload. This feature uses the Cisco IOS secure file system to persist the configuration commands that are generated.
Note The Cisco IOS configuration logger is different from the system message logging (syslog) facility. Syslog is a general logging facility for tracking system messages. The configuration logger tracks information about configuration commands entered at the CLI.
Persisted Commands
The persisted commands from the Cisco IOS configuration logger are used as an extension to the startup configuration. These saved commands provide a quick-save capability. Rather than saving the entire startup-config file, Cisco IOS software saves just the commands entered since the last startup-config file was generated.
Only the logged commands are persisted. The following additional data from the configuration logger are not persisted:
•User who logged the command
•IP address from which the user logged in
•Session and log indexes for the logged command
•Time when the command was entered
•Pre- and post-NVGEN output associated with the entered command
•Parser return code output for the entered command
The persisted commands' primary purpose is for use as a quick-save extension to the startup-config file. The additional information associated with a configuration command is not useful for quick-save purposes. If you need the additional information to be persisted across reboots (for auditing purposes), complete the following steps:
1. Enable configuration logger notification to syslog
2. Enable the syslog persistence feature
Alternatively, Cisco Networking Services, CiscoView, or other Network Management systems that manage Cisco IOS devices to keep track of configuration changes in an off-the-box storage solution can be used.
By default, upon reload, the persisted commands are appended to the startup-config file. These commands are applied only when you explicitly configure this behavior using a CLI configuration command.
How to Configure the Configuration Logger Persistency Feature
This section provides information about the following:
•Enabling the Configuration Logger Persistency Feature (required)
•Verifying and Troubleshooting the Configuration Logger Persistency Feature (optional)
Enabling the Configuration Logger Persistency Feature
The Configuration Logger Persistency feature implements a quick-save mechanism so that the time to save changes from the startup configuration is proportional to the size of the incremental changes (with respect to the startup configuration) that need to be saved. The persisted commands from the Cisco IOS configuration logger will be used as an extension to the startup configuration. The saved commands, which are used as an extension to the startup configuration, provide a quick-save ability. Rather than saving the entire startup-config file, Cisco IOS software saves just the commands entered since the last startup-config file was generated.
To enable the Configuration Logger Persistency feature, perform the following task.
SUMMARY STEPS
1. enable
2. configure terminal
3. archive
4. log config
5. logging persistent {auto | manual}
6. logging persistent reload
7. logging size entries
DETAILED STEPS
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Step 1 |
enable
Router> enable |
Enables privileged EXEC mode. •Enter your password if prompted. |
Step 2 |
configure terminal
Router# configure terminal |
Enters global configuration mode. |
Step 3 |
archive
Router(config)# archive |
Enters archive configuration mode. |
Step 4 |
log config
Router(config-archive)# log config |
Enters archive configuration-log configuration mode. |
Step 5 |
logging persistent {auto | manual}
Router(config-archive-log-cfg)# logging persistent auto |
Enables the Configuration Logging Persistent feature: •The auto keyword specifies that each configuration command will be saved automatically to the Cisco IOS secure file system. •The manual keyword specifies that you can save the configuration commands to the Cisco IOS secure file system on-demand. To do this, you must use the archive log config persistent save command. Note To enable the logging persistent auto command, you must have disk0: configured and an external flash card inserted on the router. |
Step 6 |
logging persistent reload
Router(config-archive-log-cfg)# logging persistent reload |
Sequentially applies the configuration commands saved in the configuration logger database (since the last write memory command) to the running-config file after a reload. |
Step 7 |
logging size entries
Router(config-archive-log-cfg)# logging size 10 |
Specifies the maximum number of entries retained in the configuration log. •Valid values range from 1 to 1000. •The default value is 100 entries. |
Verifying and Troubleshooting the Configuration Logger Persistency Feature
Three commands can be used to verify, archive, and clear the contents of the configuration log. For troubleshooting purposes, the command in Step 4 turns on debugging.
SUMMARY STEPS
1. show archive log config persistent
2. clear archive log config persistent
3. archive log config persistent save
4. debug archive log config persistent
DETAILED STEPS
Step 1 show archive log config persistent
This command displays the persisted commands in the configuration log. The commands appear in a configlet format. The following is sample output from this command:
Router# show archive log config persistent
!Configuration logger persistentarchive
logging persistent reload
ip address 10.1.1.1 255.255.255.0
ip address 10.2.2.2 255.255.255.0
Step 2 clear archive log config persistent
This command clears the configuration logging persistent database entries. Only the entries in the configuration logging database file are deleted. The file itself is not deleted because it will be used to log new entries. After this command is entered, a message is returned to indicate that the archive log is cleared.
Router# clear archive log config persistent
Purged the config log persist database entries successfully
Step 3 archive log config persistent save
This command saves the configuration log to the Cisco IOS secure file system. For this command to work, the archive log config persistent save command must be configured.
Step 4 debug archive log config persistent
This command turns on the debugging function. A message is returned to indicate that debugging is turned on.
Router# debug archive log config persistent
debug archive log config persistent debugging is on
Configuration Examples for the Configuration Logger Persistency Feature
This section provides a sample configuration of the Configuration Logger Persistency feature on a Cisco 7200 series router.
•Configuration Logger Persistency Configuration on a Cisco 7200 Series Router: Example
Configuration Logger Persistency Configuration on a Cisco 7200 Series Router: Example
In this example, each configuration command is saved automatically to the Cisco IOS secure file system, configuration commands saved in the configuration logger database (since the last write memory command) are applied sequentially to the running-config file, and the maximum number of entries retained in the configuration log is set to 10:
Router# configure terminal
Enter configuration commands, one per line. End with CNTL/Z.
Router(config-archive)# log config
Router(config-archive-log-config)# logging persistent auto
configuration log persistency feature enabled. Building configuration... [OK]
Router(config-archive-log-config)# logging persistent reload
Router(config-archive-log-config)# logging size 10
Router(config-archive-log-config)# archive log config persistent save
Router(config-archive-log-config)# end
Additional References
The following sections provide references related to the Configuration Logger Persistency feature.
Related Documents
Standards
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No new or modified standards are supported by this feature. |
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MIBs
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No new or modified MIBs are supported by this feature. |
To locate and download MIBs for selected platforms, Cisco IOS releases, and feature sets, use Cisco MIB Locator found at the following URL: http://www.cisco.com/go/mibs |
RFCs
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No new or modified RFCs are supported by this feature. |
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Technical Assistance
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The Cisco Support website provides extensive online resources, including documentation and tools for troubleshooting and resolving technical issues with Cisco products and technologies. To receive security and technical information about your products, you can subscribe to various services, such as the Product Alert Tool (accessed from Field Notices), the Cisco Technical Services Newsletter, and Really Simple Syndication (RSS) Feeds. Access to most tools on the Cisco Support website requires a Cisco.com user ID and password. |
http://www.cisco.com/techsupport |
Command Reference
The following commands are introduced or modified in the feature or features documented in this module. For information about these commands, see the Cisco IOS Configuration Fundamentals Command Reference at http://www.cisco.com/en/US/docs/ios/fundamentals/command/reference/
cf_book.html. For information about all Cisco IOS commands, use the Command Lookup Tool at http://tools.cisco.com/Support/CLILookup or a Cisco IOS master commands list.
•archive log config persistent save
•clear archive log config
•debug archive log config persistent
•logging persistent (config-archive-log-cfg)
•logging persistent reload
•show archive log config
Feature Information for Configuration Logger Persistency
Table 1 lists the release history for this feature.
Not all commands may be available in your Cisco IOS software release. For release information about a specific command, see the command reference documentation.
Use Cisco Feature Navigator to find information about platform support and software image support. Cisco Feature Navigator enables you to determine which Cisco IOS and Catalyst OS software images support a specific software release, feature set, or platform. To access Cisco Feature Navigator, go to http://www.cisco.com/go/cfn. An account on Cisco.com is not required.
Note Table 1 lists only the Cisco IOS software release that introduced support for a given feature in a given Cisco IOS software release train. Unless noted otherwise, subsequent releases of that Cisco IOS software release train also support that feature.
Table 1 Feature Information for Configuration Logger Persistency
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Configuration Logger Persistency |
12.2(33)SRA 12.4(11)T 12.2(33)SXH 12.2(33)SB |
The Configuration Logger Persistency feature increases the operational robustness of Cisco IOS configuration and provisioning actions by implementing a "quick-save" functionality. Effective with Cisco IOS Release 12.2(33)SRA, Release 12.4(11)T, Release 12.2(33)SXH, and Release 12.2(33)SB, Cisco IOS software saves just the commands entered since the last startup-config file was generated, rather than saving the entire startup configuration. The following sections provide information about this feature: •Information About Configuration Logger Persistency •How to Configure the Configuration Logger Persistency Feature |
Glossary
API—application programming interface.
CAF—command action function.
CDP—Cisco Discovery Protocol.
CSB—Command Status Block.
HA—high-availability architecture.
MIB—Management Information Base.
NAF—NVGEN action function.
NVGEN—nonvolatile generation.
NVRAM—nonvolatile Random Access Memory.
parse chain—A sequence of C language macros defining the syntax of a Cisco IOS command.
RP—Route Processor.
SNMP—Simple Network Management Protocol.
XML—eXtensible Markup Language.
Cisco and the Cisco logo are trademarks or registered trademarks of Cisco and/or its affiliates in the U.S. and other countries. To view a list of Cisco trademarks, go to this URL: www.cisco.com/go/trademarks. Third-party trademarks mentioned are the property of their respective owners. The use of the word partner does not imply a partnership relationship between Cisco and any other company. (1110R)
Any Internet Protocol (IP) addresses used in this document are not intended to be actual addresses. Any examples, command display output, and figures included in the document are shown for illustrative purposes only. Any use of actual IP addresses in illustrative content is unintentional and coincidental.
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