Managing NVS Cards on SRP Modules

Each SRP module contains an NVS card that stores system files. In this documentation, the NVS card on the primary SRP module is referred to as the primary NVS card; the NVS card on the redundant SRP module is referred to as the redundant NVS card.

If you have two SRP modules installed in a router, you can use NVS cards of different capacities on the SRP modules. The effective capacity of the higher-capacity NVS card will equal that of the lower-capacity NVS card.

NVS Features

The software contains a number of features that optimize the way the router restores its configuration if it is shut down improperly:

• The router tracks improper shutdowns.
• If you shut down the router improperly, it will run an investigation of the file allocation table (FAT) the next time it reboots.
• The router creates backups of critical files.
• When you install a new NVS card or restart the router after shutting it down incorrectly, a utility scans the NVS card to detect corrupt sectors. If the utility finds files or directories that contain corrupt sectors, it removes the files and directories, because they can no longer be used. The utility also fixes problems with unused sectors. If the utility cannot correct a corrupt sector, it marks the sectors so that they cannot be reused. Errors in the boot block, FAT, or root directory are fatal and cannot be corrected by the scan utility.
• In a router that contains two SRP modules, if the scanning utility detects corrupt sectors in NVS on the primary SRP module during rebooting, the primary SRP module will reboot again. Both SRP modules will now have standby status and will be rebooting. The first SRP module to complete rebooting will assume the primary role. Because the former redundant module started to reboot first, it will probably assume the primary role. When the former primary module has rebooted and the scan utility has fixed corrupt sectors in its NVS, the SRP modules will synchronize. Any files or directories removed by the scan utility will be restored during the synchronization.
• If you reboot the router before it has completely written configuration updates to NVS, the router will start with the last saved configuration. If you reboot the router after it has written the configuration updates to NVS, but before it has applied those updates to actual configuration data, the configuration update process resumes immediately following the reboot and completes before any application accesses its configuration data.

To prevent corruption of NVS cards, always issue the halt command before you remove an NVS card or an SRP module (see Removing an SRP Module). Always reboot the router using the rebooting procedure (see Chapter 10, Booting the System); do not reboot the router by switching it off and on.

Installing and Removing NVS Cards

For information about replacing NVS cards, see E-series Hardware Guide, Chapter 5, Installing Modules.

Synchronizing NVS Cards

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

If the router contains two SRP modules, it is important to keep the contents of the modules' NVS cards synchronized. Synchronization prevents the redundant NVS card from overwriting saved files on the primary NVS card if the primary SRP module fails and the redundant SRP module assumes 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 synchronization command.

Before synchronization, the router does the following:

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

Depending on the outcome of the second check, the router proceeds as follows:

• If there is enough space, the router copies new or changed files from the primary NVS card to the redundant NVS card without deleting any files on the redundant NVS card. If the router is interrupted when it is synchronizing with this method, the synchronization will resume when it has recovered from the interruption.
• If there is not enough space, the router deletes any files on the redundant NVS card that do not appear on the primary NVS card, then copies new or changed files from the primary NVS card to the redundant NVS card. If the router is interrupted when it is synchronizing with this method, it will not resume with 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 will prevent the redundant SRP module from assuming 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 NVS 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.
• Examples

host1#synchronize

host1#synchronize low-level-check all

host1#synchronize low-level-check configuration

• There is no no version.

Synchronizing NVS Cards of Different Capacities

If the capacity of the primary NVS card is equal to or smaller than that of the redundant NVS card, the router copies all the files from the primary NVS card to the redundant NVS card. However, if the capacity of the primary NVS card exceeds that of the redundant NVS card, the router creates an invisible synchronization reserve file on the primary NVS card, provided that there is enough space for the file.

The purpose of the synchronization file is to prevent the creation of data that will not fit on the redundant NVS card. The file contains no useful data, and is not visible when you view the files in NVS. The size of the file is equal to the difference in capacities of the two NVS cards. For example, if the primary NVS card has a capacity of 224 MB, and the redundant NVS card has a capacity of 220 MB, the size of the synchronization file is 4 MB, and only 220 MB of space is available on the primary NVS card.

If there is not enough space on the primary NVS card to create the synchronization reserve file, the synchronize command fails, and you see a warning message on the console. To resolve this issue, either delete unwanted files from the primary NVS card or replace the redundant NVS card with a higher-capacity NVS card.

Disabling Autosynchronization

If autosynchronization is enabled while you are copying very long scripts or installing new software releases, it detects a disparity between the modules during the middle of the process. This feature causes significant unnecessary synchronization, resulting in prolonged copy times.

If you have installed a redundant SRP module, perform the following steps before copying long scripts:

1. Turn off autosynchronization with the disable-autosync command.
2. Perform the installation or copy the script.
3. Reenable autosynchronization with the no disable-autosync command.
4. Manually synchronize the modules with the synchronize command.

Refer to the commands and guidelines in the previous section and below.

disable-autosync

• Use to turn off automatic synchronization between the primary and redundant SRP modules.
• Example

host1(config)#disable-autosync

• Use the no version to revert to the default situation, in which automatic synchronization runs as a background process every 5 minutes.

Validating and Recovering Redundant SRP File Integrity

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

Even when NVS cards on the primary and redundant SRP modules are synchronized, differences can exist in the content of files that reside on the primary NVS card and the redundant NVS card. You can use the flash-disk compare command to detect these differences so you can validate and, if necessary, recover the file integrity of the redundant SRP module.

The flash-disk compare command validates only those files that are synchronized between the primary and redundant SRP modules. It does not compare files that are normally excluded from the synchronization process, such as log files and core dump files. The command uses a simple checksum error detection algorithm to compare the contents of a file residing on the NVS card of the primary SRP module with the contents of the same file residing on the NVS card of the redundant SRP module.

To validate and recover redundant SRP file integrity:

1. Ensure that the file systems on the primary NVS card and the redundant NVS card are synchronized. (See Synchronizing NVS Cards for details.)
2. Issue the flash-disk compare command, specifying whether to perform the checksum validation for all files in NVS or only for configuration files.

host1#flash-disk compare all

host1#flash-disk compare configuration

The flash-disk compare configuration command, which validates only configuration files, excludes larger files such as software releases and scripts from the validation process. As a result, this command takes less time to complete than the flash-disk compare all command, which validates all NVS files.

3. Review the flash-disk compare output to determine whether any files failed the checksum validation.

If the flash-disk compare command detects differences in the content of one or more files, the router reports a checksum test failure.

4. If one or more files failed the checksum validation, determine whether the corrupted files reside on the primary SRP module or on the redundant SRP module.
5. If the corrupted file resides on the primary SRP module, issue the srp switch command to force a switch from the primary SRP module to the redundant SRP module.

This action ensures that the error-free version of the file will be on the SRP module that assumes control after the switch.

6. Issue the synchronize command with the low-level-check keyword to force the router to:

• Validate all files in NVS (when you use the all keyword) or only configuration files in NVS (when you use the configuration keyword).
• Synchronize all files that failed the checksum test during the flash-disk compare command, as well as any other unsynchronized files.

host1#synchronize low-level-check all

host1#synchronize low-level-check configuration

This action should resolve any file discrepancies between the primary and redundant SRP modules and restore SRP file integrity.

NOTE: Both the flash-disk compare and synchronize low-level-check commands perform CPU-intensive processing that can take several minutes to complete. For best results, do not run these commands simultaneously on the same router. In addition, do not run multiple instances of the flash-disk-compare command simultaneously on the same router.

flash-disk compare

• Use to perform a checksum validation that compares the contents of the NVS file system on the primary SRP module with the contents of the NVS file system on the redundant SRP module.
• The command validates only those files that are synchronized between the primary and redundant SRP modules; it does not validate log files, core dump files, and other files that are excluded from the system synchronization process.
• Specify one of the following keywords:

• all—Compares all files in NVS; this option can take several minutes to complete.
• configuration—Compares only configuration files; this option takes less time to complete because it compares only a subset of the files in the NVS file system.

• If all files pass the validation test, the router reports that all checksums matched and displays the total number of files and total number of bytes of information compared.
• If one or more files fail the validation test, the router reports a checksum test failure and does not display the total number of files and bytes compared.
• If one or more of the following conditions exist, the command fails and the router displays a message that explains why it cannot perform the checksum test:

• The file systems on the primary NVS card and the redundant NVS card are not synchronized.
• The router does not contain a redundant SRP module.
• The redundant SRP module is offline.

• Example 1—Shows output when all files passed the validation test

host1#flash-disk compare all

WARNING: This command may take several minutes to complete.

Proceed? [confirm]

WARNING: No changes should be made to the system while this command is in

         progress.

Please wait.........................................................

All file checksums matched.

Number of Files = 866

Number of Bytes = 61660650

• Example 2—Shows output when one or more configuration files failed the validation test

host1#flash-disk compare configuration

WARNING: This command may take several minutes to complete.

Proceed? [confirm]

WARNING: No changes should be made to the system while this command is in

         progress.

Please wait......

At least one configuration file failed checksum test.

• There is no no version.

synchronize

• Use to force the NVS file system of the redundant SRP module to synchronize with the NVS 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 validation test during the flash-disk-compare command as well as any other files that are unsynchronized.
• When you use the low-level-check keyword, you must also specify one of the following keywords:

• all—Validates all files in NVS, and synchronizes all files that failed the checksum test as well as any other unsynchronized files; this option can take several minutes to complete.
• configuration—Validates all configuration files in NVS, and synchronizes all files that failed the checksum test as well as any other unsynchronized files; this option takes less time to complete because it validates only a subset of the files in the NVS file system.

• If one or more of the following conditions exist when you use the low-level-check keyword, the command fails and the router displays a message that explains why it cannot perform the synchronization:

• The router does not contain a redundant SRP module.
• The redundant SRP module is offline.
• The armed releases are different on the primary SRP and redundant SRP.

• Examples

host1#synchronize

host1#synchronize low-level-check all

host1#synchronize low-level-check configuration

• There is no no version.

Reformatting the Primary NVS Card

You can reformat the primary NVS card. To do so:

1. Access Boot mode.

1. From Privileged Exec mode, enter the reload command. Information about the reloading process is displayed.
2. When the countdown begins, press the <mb> key sequence (case-insensitive).

The CLI enters Boot mode (:boot## prompt). If you do not press the <mb> key sequence, the reloading process continues and returns the CLI to the normal User Exec mode.

2. Issue the flash-disk initialize command.

flash-disk initialize

• Use to reformat the NVS card.
• You can perform a low-level format of the NVS card.
  

  NOTE: This command is available only in the Boot mode.

  
  
• Example

host1#halt primary-srp 

host1#reload

WARNING: Execution of this command will cause the system to reboot.

Proceed with reload? [confirm] 

Reload operation commencing, please wait...

[ Press mb]

:boot##flash-disk initialize

• There is no no version.

Copying the Image on the Primary SRP Module

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

You can copy the contents of NVS on the primary SRP module to a spare NVS card. To do so:

1. Access Boot mode.

1. From Privileged Exec mode, enter the reload command. Information about the reloading process displays.
2. When the countdown begins, press the <mb> key sequence (case-insensitive).

This action puts the CLI in Boot mode (:boot## prompt).
If you do not press the <mb> key sequence, the reloading process continues and returns the CLI to the normal User Exec mode.

2. Issue the flash-disk duplicate command.
3. Follow the instructions on the screen. When prompted, insert the original or spare NVS card in the primary SRP module.

flash-disk duplicate

• Use to copy the contents of the primary NVS card to a spare NVS card.
• The primary and spare NVS cards must be from the same manufacturer and must have the same size.
  

  NOTE: This command is available only in the Boot mode.

  
  
• When you issue the flash-disk duplicate command, insert the original and spare NVS cards when prompted. The router copies the NVS contents incrementally, so you may need to exchange the NVS cards several times.
• Example

host1#halt primary-srp 

host1#reload

WARNING: Execution of this command will cause the system to reboot.

Proceed with reload? [confirm] 

Reload operation commencing, please wait...

[ Press mb]

:boot##flash-disk duplicate

• There is no no version.

Scanning NVS Cards

You can find both structural errors in the data in NVS and physical errors in the NVS card. You can also remove files with errors, and attempt to repair structural or physical errors.

check-disk

• Use to find and repair structural inconsistencies and damage in the DOS file router in NVS on the primary SRP module.
  

  NOTE: This command is available only in the Boot mode.

  
  
• If the router contains primary and redundant modules, only NVS on the primary SRP module will be scanned.
• Example

:boot##check-disk

Copyright (c) 1993-1996 RST Software Industries Ltd. Israel. All rights reserved

ver: 2.6 FCS

Disk Check In Progress ...

        total disk space (bytes) :                    512,122,880

        bytes in each allocation unit :               8,192

        total allocation units on disk :              62,515

        bad allocation units :                        1

        available bytes on disk :                     120,651,776

        available clusters on disk :                  14,728

        maximum available contiguous chain (bytes) :  120,651,776

        available space fragmentation (%) :           0

        clusters allocated :                          47,786

Done Checking Disk.

• There is no no version.

flash-disk scan

• Use to find and repair files with physical errors in NVS. These errors are created if the router is not powered down or reset correctly.
  

  NOTE: This command is available only in the Boot mode.

  
  
• If the router contains primary and redundant modules, only NVS on the primary SRP module will be scanned.
• If the repair fails, the router will no longer use the corrupted areas.
• Example
  In this example, the user scans NVS and finds one file with an error. The user then issues the flash-disk scan with the repair keyword to remove the file. Finally, the user scans NVS again, and finds no files with errors.

:boot##flash-disk scan

Proceed with Flash disk scan? [confirm]

Srp PCMCIA Card Scan...

Boot Block OK

File Allocation Table OK

Root Directory OK

Checking File Space

Please Wait...

Checking Free Space

Please Wait...

PCMCIA Card Scan Detected Errors in:

\\images\ct1Diag\ct1Diag3c440e9e.cmp

PCMCIA Card Scan successful!

:boot##flash-disk scan repair

WARNING: Execution of this command may cause the contents of the Flash disk 
to be modified.

Proceed with Flash disk scan? [confirm]

Srp PCMCIA Card Scan...

Boot Block OK

File Allocation Table OK

Root Directory OK

Checking File Space

Please Wait...

Checking Free Space

Please Wait...

PCMCIA Card Scan Removed:

\\images\ct1Diag\ct1Diag3c440e9e.cmp

PCMCIA Card Scan successful!

:boot##flash-disk scan

Proceed with Flash disk scan? [confirm]

Srp PCMCIA Card Scan...

Boot Block OK

File Allocation Table OK

Root Directory OK

Checking File Space

Please Wait...

Checking Free Space

Please Wait...

PCMCIA Card Scan successful!

• There is no no version.

Monitoring NVS Cards

Use the show nvs command to monitor the status of NVS on the primary SRP module. Use the show flash command to view information about the NVS card.

show nvs

• Use to monitor NVS status.
• Field descriptions

• total nvs file sizes—Sum of sizes of all files in NVS, in bytes
• total nvs file errors—Number of read and write errors in all files in NVS
• nvs flash in use—NVS used, in bytes
• available nvs flash—NVS available, in bytes

• Example

host1#show nvs

total nvs file sizes =  228864

total nvs file errors = 0

nvs flash in use =      1265152

available nvs flash =   35435008

show flash

• Displays information about the NVS card.
• Field descriptions

• Flash Manufacturer—Name of manufacturer of the NVS card
• Capacity—Total capacity of the NVS card, in bytes

• Example

host1#show flash

Flash Manufacturer:             STI     Capacity:       224133120