🛠️How to Change Root Files in Rescue Mode (OVH Public Cloud)

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This guide explains how to mount the root disk, edit system files, or change the root password when using Rescue Mode on an OVH Public Cloud instance.

🔐 When to Use Rescue Mode

Rescue mode is useful when:

  • You’ve lost access to the server (SSH key or password issues).
  • A misconfiguration prevents the system from booting correctly.
  • You need to repair, back up, or recover system files.

🛠️ Step-by-Step Instructions

1. Reboot into Rescue Mode

  1. Log in to the OVH Control Panel.
  2. Go to your Public Cloud Instance.
  3. Click the ⋮ menu (three dots) at the top right.
  4. Select “Reboot in rescue mode”.
  5. Choose the “rescue-pro” image.
  6. You’ll be provided with a temporary root password in the console. If you’ve added an SSH key previously, you’ll be logged in automatically via key-based authentication.

2. Access the Instance in Rescue Mode

Login via SSH:

ssh [email protected]

If no SSH key is installed, use the root password provided in the console.

3. Check Mounted Filesystems

Run:

df -h

Example output:

Filesystem      Size  Used Avail Use% Mounted on
/dev/sda1       2.4G  1.5G  784M  66% /
...

/dev/sda1 is the temporary rescue system — not your main system disk.

4. Identify Your Attached System Disk

Run:

lsblk

Example:

NAME   MAJ:MIN RM  SIZE RO TYPE MOUNTPOINT
sda      8:0    0  2.5G  0 disk
└─sda1   8:1    0  2.5G  0 part /
sdb      8:16   0   40G  0 disk
└─sdb1   8:17   0   40G  0 part

Here, /dev/sdb1 is the root partition of your actual system disk.

5. Mount the System Disk

mount /dev/sdb1 /mnt

Confirm it’s mounted:

df -h

You should see:

/dev/sdb1        40G  7.0G   31G  19% /mnt

6. Access System Files

Switch to the mounted disk:

cd /mnt

Check contents:

ls

You’ll see the standard root directory structure:

bin  boot  dev  etc  home  lib  media  mnt  opt  proc  root  sbin  tmp  usr  var

🔑 Example: View Authorized SSH Keys

cat /mnt/root/.ssh/authorized_keys

You can add your new key here if you’re locked out.

🔒 Change the Root Password

  1. Chroot into the mounted system:
chroot /mnt
  1. Change the root password:
passwd

Enter and confirm the new password.

  1. Exit chroot:
exit

🔁 Reboot Normally

Once you’ve finished your tasks:

  1. Go back to the OVH Control Panel.
  2. Click the menu and select “Exit rescue mode”.
  3. The instance will reboot normally using the updated configuration or password.

🖥️ Using OpenStack CLI (Optional)

If you prefer using OpenStack CLI tools:

  • Enter rescue mode:
nova rescue INSTANCE_ID
  • Exit rescue mode:
nova unrescue INSTANCE_ID

✅ Summary

TaskCommand/Action
Identify diskslsblk
Mount real system diskmount /dev/sdb1 /mnt
View root filesystemls /mnt/root/
Change root passwordchroot /mnt && passwd
Restore normal bootExit rescue mode via OVH panel

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