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Accelerating the LN Series Router Boot-Up Process

 

To minimize the time required for an LN Series router to become operational, you can configure these BOOT features to accelerate the startup process:

  • Disable or enable power-on self test (POST) using the no_run_post environmental variable.

  • Disable or enable file system cleanup using the fs_clean_boot environmental variable.

  • Remove temporary files left over from the IDP security package installation.

Best Practice

We recommend that you only enable the no_run_post and the fs_clean_boot environmental variables in networks when the time to boot the platform is critical to system operations.

These options are not mutually exclusive and not linked. You can choose to set both options, set only one option, or set neither of the options. If neither option is set, the LN Series router’s default behavior remains unchanged; POST runs automatically, and the optional file system cleanup is not performed.

This section contains the following topics:

Accessing the LN Series Router BOOT> Prompt

You set the no_run_post and the fs_clean_boot environmental variables from the BOOT> prompt.

To access the LN Series router BOOT> prompt:

  1. Obtain console access to the LN Series router.
  2. Start the boot cycle by rebooting or re-powering the router by entering the request system reboot command at the console and answering yes to reboot the system prompt. When the Boot Flash information displays on the console, press the space bar.
    lab@md-ln4-2> request system reboot
  3. After pressing the space bar, the process continues performing some system tests, and then the boot process stops at the BOOT> prompt.
  4. For available commands, enter help or ? at the BOOT> prompt.

Disabling or Enabling POST

Disabling POST

To disable the POST feature:

Note

Only the first character of the environmental variable is evaluated. If the variable is not set, or if the first character of the variable’s value is zero (0), then the default behavior for POST (runs automatically) and file system cleanup (not performed) is followed.

When you disable POST, the standard set of POST diagnostic tests are skipped. The following sample console output shows that the POST feature is disabled:

Enabling POST

To enable the POST feature and run the full set of POST diagnostic tests during the boot-up process:

Note

The POST feature’s default setting is enabled.

or

When you enable POST, the full set of POST diagnostic tests run. The following sample console output shows that the POST feature is enabled:

Disabling or Enabling File System Cleanup

Disabling File System Cleanup

To disable the file system cleanup feature:

Note

The file system cleanup’s default setting is disabled.

or

When you disable the file system cleanup feature, no files are deleted during the boot process. The following sample console output shows that the file system cleanup feature is disabled:

Best Practice

We recommend that you disable file system cleanup before performing a Junos OS upgrade. If you enable file system cleanup, you cannot roll back Junos OS to a previous version, and in case of an upgrade failure, can result in a non-functioning router. By setting disabling file system cleanup, you maintain the option of having a recoverable rollback image available, if necessary.

Enabling File System Cleanup

When you enable the file system cleanup feature, certain unnecessary files are identified and deleted early in the boot process. To enable the file system cleanup feature to select and delete files:

When you enable file system cleanup, temporary, log, and other unnecessary files are identified and deleted. The following sample console output shows that the file system cleanup feature is enabled:

This additional sample console output shows the file system cleanup feature is enabled with non-volatile memory read-only (NVMRO) switch enabled as well:

No files are deleted when NVMRO is set to Read-only regardless of the fs_clean_boot setting.

After the system completes its boot process, you can review the list of removed files by reading the file_cleanup.log file:

root@ln1000% cat /var/tmp/file_cleanup.log

To determine the value of the fs_clean_boot environmental variable using the CLI:

root@ln1000% sysctl kern.fs_clean_boot

Removing Temporary IDP Package Installation Files

The fs_clean_boot option does not remove temporary files left over from the IDP security package installation. To remove the temporary files, run the separate IDP cleanup request after installing or upgrading the IDP package:

user@ln1000>request security idp storage-cleanup downloaded-files