Last updated 04 April 2019
Rescue mode is a tool on your Dedicated Server. You can use it to boot into a temporary operating system, in order to diagnose and resolve issues.
This guide will show you how to activate and use your server's rescue mode.
- administrative (root) access to your Dedicated Server via SSH
You can activate rescue mode by logging into the OVH Control Panel. Select your server by going to the
Dedicated section, then
Dedicated Servers. Then go to
Server status >
General information >
... and click
Edit to change the boot mode.
On the next screen, select
Boot in rescue mode. If your server has a Linux-based OS, select
rescue64-pro from the dropdown list. If your server runs on Windows or FreeBSD, select
bsd-rescue-pro respectively. Lastly, enter your email address in the text field, then click
Confirm your options on the next screen, then reboot your server to apply your changes.
Your server will now reboot in rescue mode, and you will receive the credentials for logging in via the email address you provided. To exit rescue mode, simply change the boot mode back to
Boot on the hard disk, then reboot your server again.
Use the web interface.
Once your server has rebooted, you will receive an email with your rescue mode access credentials. The email will also contain a link to the rescue mode web interface, which you can use to perform the following tests:
- Hard disks. Checks their integrity with SMART tests.
- Processors. Checks that they are functioning normally. (This test takes a while.)
- Partitions (states). Checks the states of readers.
- Partitions (file systems). Checks the server’s file system.
- Partitions (explore). Launches a browser for exploring files. You cannot edit them with this tool, but you can back them up.
- Memory. Checks the RAM installed on the server. (This test takes a while.)
- Network. Checks the connection to an OVH-internal reference system as well as the connection to your browser.
Use SSH (command line).
If you are using an SSH key (also active in the OVH Control Panel), you will not be sent a password. Once the server is in rescue mode, you can connect directly via your SSH key.
Once your server has rebooted, you will receive an email with your rescue mode access credentials. You will then need to access your server via the usual command lines, using the root password for rescue mode rather than your own.
ssh root@your_server_IP root@your_server_password:
Your SSH-Client will likely block the connection due to a mismatch of the ECDSA fingerprint. This is normal because the rescue mode uses its own temporary ssh server.
One way around this, is commenting the fingerprint of your regular system by adding a
# in front of its line in the known_hosts file. And reverting that change when returning to normal boot.
For most changes you make to your server via SSH while in rescue mode, you will need to mount a partition. This mode has its own temporary file system, so any file system changes you make in rescue mode will be lost once you reboot the server back in normal mode.
You can mount partitions using the
mount command in SSH. Firstly, you will need to list your partitions, so that you can retrieve the name of the partition you would like to mount. You can refer to the following code examples:
rescue:~# fdisk -l Disk /dev/hda 40.0 GB, 40020664320 bytes 255 heads, 63 sectors/track, 4865 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Device Boot Start End Blocks Id System /dev/hda1 * 1 1305 10482381 83 Linux /dev/hda2 1306 4800 28073587+ 83 Linux /dev/hda3 4801 4865 522112+ 82 Linux swap / Solaris Disk /dev/sda 8254 MB, 8254390272 bytes 16 heads, 32 sectors/track, 31488 cylinders Units = cylinders of 512 * 512 = 262144 bytes Device Boot Start End Blocks Id System /dev/sda1 1 31488 8060912 c W95 FAT32 (LBA)
Once you have found the name of the partition you want to mount, use the command below:
rescue:~# mount /dev/hda1 /mnt/
Your partition will now be mounted. You can then carry out operations on the file system.
If your server uses a softRAID configuration, you will need to mount your RAID volume (generally
Once your server has rebooted, you will receive an email with your rescue mode access credentials. To use them, you will need to download and install a VNC console, or use the
IPMI module in the OVH Control Panel.
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