Synchronizing Flash Cards

Note: The information in this section does not apply to the ERX-310 router, which does not support SRP module redundancy.

When the router contains two SRP modules, the contents of the modules’ flash cards need to be synchronized. Synchronization prevents the redundant flash card from overwriting saved files on the primary flash card if the primary SRP module fails and the redundant SRP module takes control.

By default, autosynchronization is enabled on the router. Autosynchronization runs as a background process every 5 minutes, tracking changes in image, configuration, and script files, and keeping the two SRP modules synchronized. You can also synchronize the SRP modules manually by issuing the synchronize command.

Before synchronization, the router does the following:

• Verifies that critical files on the primary SRP module are present. If files are missing, the router does not proceed with the synchronization.
• Verifies whether there is enough space on the redundant flash card to copy all the new or changed files from the primary flash card.

Depending on the outcome of the space verification, the router proceeds as follows:

• If the card has enough space, the router copies new or changed files from the primary flash card to the redundant flash card without deleting any files on the redundant flash card. If the router is interrupted while it is synchronizing with this method, the synchronization resumes when it has recovered from the interruption.
• If the card does not have enough space, the router deletes any files on the redundant flash card that do not appear on the primary flash card, then copies new or changed files from the primary flash card to the redundant flash card. If the router is interrupted while it is synchronizing with this method, it does not resume the synchronization when it has recovered from the interruption.

If an SRP synchronization is in progress or has failed and the router is recovering, the router prevents the redundant SRP module from taking the primary role while the primary is rebooting and for 30 seconds after the primary module has rebooted. These conditions prevent a redundant SRP module with corrupted or missing files from becoming the primary and overwriting files or directories on the primary module.

synchronize

• Use to force the file system of the redundant SRP module to synchronize with the flash file system of the primary SRP module.
• If you synchronize the redundant SRP module with the primary SRP module and the redundant module is armed with a release different from the one it is currently running, the redundant SRP module is automatically rebooted to load the armed release.
• Optionally, you can use the low-level-check keyword to force the router to validate all files or only configuration files in NVS, and to synchronize all files that failed the checksum test during the flash-disk-compare command as well as any other files that are unsynchronized. See Validating and Recovering Redundant SRP File Integrity for details.

  Note: In most cases, use the synchronize command instead of the synchronize low-level-check command. The synchronize low-level-check command is provided for troubleshooting, and is intended to be used under direction from JTAC.

• Examples

  host1#synchronize

  host1#synchronize low-level-check all

  host1#synchronize low-level-check configuration

• There is no no version.
• See synchronize.

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