How to use rescue mode on a VPS

Wissensdatenbanken

KB0047651

How to use rescue mode on a VPS


Icons/System/eye-open Created with Sketch. 23682 Ansichten 12.01.2025 Cloud / Virtual Private Server

Objective

Rescue mode is a tool provided by OVHcloud to boot your VPS into a temporary operating system. You can then access your system in order to run diagnostic tasks and resolve various issues, for example:

If you are facing a problem with your system, performing checks in rescue mode helps to determine whether it is related to software installed on the VPS or caused by a more profound issue. Before contacting our support teams, we recommend to gather test results and exclude any software errors by using rescue mode.

If you have any services still online, rescue mode will interrupt them as the server is being rebooted into the auxiliary rescue environment.

This guide explains how to boot a VPS into rescue mode in your OVHcloud Control Panel and how to use it to access your file system.

Requirements

OVHcloud provides services for which you are responsible with regard to their configuration and management. It is therefore your responsibility to ensure that they function correctly.

This guide is designed to assist you in common tasks as much as possible. Nevertheless, we recommend contacting a specialist service provider or reaching out to our community if you experience any issues.

Instructions

Activating rescue mode

Log in to the OVHcloud Control Panel, go to the Bare Metal Cloud section and select your server from Virtual Private Servers.

On the Home tab, click on ... next to "Boot" in the section Your VPS.

Rescue

Select Reboot in rescue mode from the menu and click Confirm in the popup window.

Using rescue mode

After initiating the reboot, a progress bar will indicate the duration of the task. Note that this can take several minutes.

You will receive an automated email with the SSH credentials for rescue mode access. Please wait for the email to arrive before taking any further action. This email can also be viewed in your OVHcloud Control Panel: Click on the name associated with your NIC handle (Customer ID) in the menu bar in the top right-hand corner, then select Service emails.

Please note that if you are no longer the technical contact of the server, your will not receive the email. For more information, refer to our guide on Managing contacts for your services.

You will then need to access your server via SSH, using the temporary password generated for the rescue mode.

Example:

ssh root@vps-x11x11xyy.vps.ovh.net
root@vps-x11x11xyy.vps.ovh.net's password:

Your SSH client will normally block the connection at first due to a mismatch of the ECDSA fingerprint. This is because the rescue mode uses its own temporary SSH server. To resolve this, you need to edit the file known_hosts of your local .ssh folder.
You have two options:

  • Delete the fingerprint from the file. Your SSH client will then add a new fingerprint entry for the server when you are no longer using rescue mode. For a detailed explanation, refer to the section "Login and fingerprint" in our SSH introduction guide.

  • Temporarily disable the fingerprint. Open the file known_hosts with a text editor and identify the fingerprint string of your server by its IP address. Add the character # at the start of the line. As a result, this line is now a "comment" and will be ignored by applications reading the file. Remember to revert this change before rebooting the VPS.

For most changes you make to your server via SSH while in rescue mode, you will need to mount the system partition.

Once you are connected, verify the attached disks with this command:

lsblk

The result will look similar to the following example output:

NAME    MAJ:MIN RM   SIZE RO TYPE MOUNTPOINTS
sda       8:0    0   2.9G  0 disk
└─sda1    8:1    0   2.9G  0 part /
sdb       8:16   0   160G  0 disk
├─sdb1    8:17   0 159.9G  0 part
├─sdb14   8:30   0     4M  0 part
└─sdb15   8:31   0   106M  0 part

In rescue mode, sda is the rescue mode disk and sda1 is the primary rescue partition mounted on /.

In this example, the primary disk of the VPS is sdb and the system partition is sdb1 (indicated by the size).

Mount this partition with the following command:

mount /dev/sdb1 /mnt/

Your files are now accessible from the mount point /mnt:

cd /mnt
ls

You should then see your file system displayed:

bin  boot  dev  etc  home  lib  lib32  lib64  libx32  lost+found  media  mnt  opt  proc  root  run  sbin  snap  srv  sys  tmp  usr  var

Before you can manipulate this partition however, you need to open it for write access which you can do with the following command:

chroot /mnt

You can now apply changes to your system, for example reset user passwords and SSH keys.

Once you have completed your actions in rescue mode, reboot the VPS again in the regular mode from the OVHcloud Control Panel.

rescue mode control panel

Troubleshooting boot issues

If you encounter errors when rebooting a VPS, use the following procedure:

  • Check the KVM in the OVHcloud Control Panel for relevant information as to why the VPS is unable to start. Consult our KVM guide for help with this feature.
  • If the KVM shows that the VPS is stuck in boot or unable to find the disk, ensure you have boot logs enabled. Relay the pertinent logs to our support teams for further investigations by creating a support request.

Go further

Getting started with SSH

Recovering server access if your user password is lost

How to replace an SSH key pair

Checking the file system on a VPS

Join our community of users.

Zugehörige Artikel