> For the complete documentation index, see [llms.txt](https://linux-tutorial-cli.gitbook.io/linux-cli-tutorial/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://linux-tutorial-cli.gitbook.io/linux-cli-tutorial/txt-files/file-systems-cocepts/lpic3-306/crm_shadow.md).

# crm\_shadow

`crm_shadow` is a utility within the crmsh (Cluster Resource Manager Shell) toolkit used to work with a “shadow” copy of the cluster configuration (the CIB, or Cluster Information Base) in a Pacemaker-managed cluster. Although its usage is not as widely documented as some other crmsh commands, its primary functions generally include:

* **Backup:**\
  Creating a shadow copy of the current active configuration. This backup can serve as a point-in-time snapshot of the cluster’s settings, which is useful for change management or for recovering from misconfigurations.
* **Comparison:**\
  Comparing the current active CIB against a previously saved shadow copy. This helps administrators identify what changes have been made over time and can aid in troubleshooting configuration-related issues.
* **Restore:**\
  In some implementations, `crm_shadow` may provide functionality to restore the cluster configuration from a shadow copy. This can be valuable if a recent change leads to instability or if the active CIB becomes corrupted.

### Typical Operations

* **Save the Active CIB to a Shadow File:**\
  This operation creates a backup of the current configuration.

  ```bash
  crm_shadow --save /path/to/shadow-cib.xml
  ```

  *(Note: The actual flag or syntax might differ depending on the version of crmsh.)*
* **Compare a Shadow CIB with the Active Configuration:**\
  To display differences between the saved configuration and the current active one:

  ```bash
  crm_shadow --diff /path/to/shadow-cib.xml
  ```
* **Restore the CIB from a Shadow Copy:**\
  This operation would replace the active configuration with the saved one:

  ```bash
  crm_shadow --restore /path/to/shadow-cib.xml
  ```

### Considerations

* **Version Dependency:**\
  The availability and exact syntax of `crm_shadow` can vary depending on the crmsh version and distribution. It’s recommended to check the help output:

  ```bash
  crm_shadow --help
  ```

  for the specific options and usage supported in your environment.
* **Caution When Restoring:**\
  Because the CIB controls the cluster configuration, restoring from a shadow copy should be done with care—ideally after verifying that the shadow file is correct and tested in a non-production environment.

### Conclusion

While `crm_shadow` may not be as commonly used or documented as other crmsh commands like `crm_mon` or `crm_resource`, it plays a valuable role in cluster configuration management. By allowing administrators to create, compare, and potentially restore a shadow copy of the CIB, it provides an additional layer of safety and change control in managing Pacemaker clusters.

If you plan to use `crm_shadow`, be sure to consult your crmsh version’s help documentation and test its functionality in a controlled setting before relying on it in production.