# Switching NFS Backing file

\
Trilio employs a base64 hash to establish the mount point for NFS Backup targets, ensuring compatibility across multiple NFS Shares within a single Trilio installation. This hash is an integral component of Trilio's incremental backups, functioning as an absolute path for backing files.

*Consequently, during a disaster recovery or rapid migration situation, the utilization of a mount bind becomes necessary.*

In scenarios that allow for a comprehensive migration period, an alternative approach comes into play. This involves modifying the backing file, thereby enabling the accessibility of Trilio backups from a different NFS Share. The backing file is updated to correspond with the mount point of the new NFS Share.

## Backing file change script

Trilio provides a shell script for the purpose of changing the backing file.\
This script is used after the Trilio appliance has been reconfigured to use the new NFS share.

### Downloading the shell script

{% hint style="success" %}
Please request the shell script from your Trilio Customer Success Manager or Customer Success Engineer by opening a case from our Customer Portal. It is not publically available for download at this time.
{% endhint %}

### Prerequisites

The following requirements need to be met before the change of the backing file can be attempted.

* The Trilio Appliance has been reconfigured with the new NFS Share
* The Openstack environment has been reconfigured with the new NFS Share
  * Please check [here ](https://docs.trilio.io/openstack/t4o-5.x/deployment/installing-on-rhosp)for Red Hat Openstack Platform
* The workloads are available on the new NFS Share
* The workloads are owned by nova:nova user

### Usage

The shell script is changing one workload at a time.

{% hint style="danger" %}
The shell script has to run as nova user, otherwise the owner will get changed and the backup can not be used by Trilio.
{% endhint %}

Run the following command:

```
./backing_file_update.sh /var/triliovault-mounts/<base64>/workload_<workload_id>
```

with

* `/var/triliovault-mounts/<base64>/` being the new NFS mount path
* `workload_<workload_id>` being the workload to rebase

### Logging of the procedure

The shell script is generating the following log file at the following location:

```
/tmp/backing_file_update.log
```

The log file will not get overwritten when the script is run multiple times.\
Each run of the script will append the available log file.