Restoring the Cloud Backup agent after a Linux kernel update

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Updated at April 1, 2025

Updating the Linux kernel on a VM or BareMetal server connected to Cloud Backup may affect the performance of the Cloud Backup agent: it will not be able to create a backup of the VM/server or recover the VM/server from a backup.

This may affect the agent’s performance, since the SnapAPI module (developed by the backup provider for the agent to work with disks and built by the DKMS framework for a specific Linux kernel) may not update after updating the kernel and may therefore cease to match the kernel version.

To restore the Cloud Backup agent’s performance affected by a Linux kernel update, you need to update the version of the Linux kernel headers DKMS refers to when building the SnapAPI module. Once the kernel header version matches the kernel version, DKMS will rebuild the SnapAPI module for the required Linux kernel version at the next start of the VM or BareMetal server.

Debian/Ubuntu

Make sure the Linux kernel version does not match that of the kernel headers:
- To find out the Linux kernel version, run this command in the terminal:
```
uname -r
```
  Result:
```
6.1.0-31-amd64
```
- To find out the version of the Linux kernel headers, run this command:
```
sudo apt list --installed | grep header
```
  Result:
```
linux-headers-6.1.0-27-amd64/stable,now 6.1.115-1 amd64 [installed]
linux-headers-6.1.0-27-common/stable,now 6.1.115-1 all [installed,automatic]
```
As you can see from the command outputs, the versions are different: the Linux kernel version is 6.1.0-31, and the Linux kernel header version is 6.1.0-27.
Install the linux-headers package for the new Linux kernel:
```
sudo apt install linux-headers-$(uname -r)
```

Make sure the new kernel headers have been added:

sudo apt list --installed | grep header

Result:

linux-headers-6.1.0-27-amd64/stable,now 6.1.115-1 amd64 [installed]
linux-headers-6.1.0-27-common/stable,now 6.1.115-1 all [installed,automatic]
linux-headers-6.1.0-31-amd64/stable-security,now 6.1.128-1 amd64 [installed]
linux-headers-6.1.0-31-common/stable-security,now 6.1.128-1 all [installed,automatic]

Reboot your OS:
```
sudo reboot
```
During the reboot, the DKMS framework will rebuild the SnapAPI module for the required Linux kernel version and the Cloud Backup agent will start operating.

If you were unable to recover your Cloud Backup agent for any reason, contact support.

Restoring the Cloud Backup agent after a Linux kernel update

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