How to activate the rescue mode

Overview Rescue Boot

In case of server failure (configuration error, hard disk errors), the rescue mode restarts your server via the network on a minimal operating system. You can use rescue mode to debug your server and recover your system data.

The rescue mode creates a ramdisk with the content of a downloaded rootfs. You will have access to all your disks and will be able to perform debug and rescue actions. After disabling rescue mode, you will have to reboot your server. In addition, your server needs to be running to switch to rescue mode.

Requirements

Activating Rescue Mode

1 . In the Compute section, select a running server

2 . Click on the Advanced Settings tab

3 . Click on Use rescue image in the Boot Mode section

5 . Click on Save to update the boot configuration

6 . Click on Reboot in the top right corner of the page

7 . A pop-up appears to confirm the reboot of your server, click on Reboot this server to initiate the reboot

Your server is being rebooted into rescue mode.

Disabling Rescue Mode

1 . In the Compute section, select a running server

2 . Click on the Advanced Settings tab

3 . Several options are available in the Boot Mode section to reboot the server:

  • A virtual Cloud Instance can either boot from the local configuration by selecting Use local boot or from a bootscript in the Use bootscript section

  • A BareMetal Cloud Instance can boot in normal mode by selecting bootscript in the Use bootscript section

5 . Click on Save to update the bootscript Settings

6 . Click on Reboot in the top right corner of the page

7 . A pop-up appears to confirm the reboot of your server, click on Reboot this server to initiate the reboot

Your server is being rebooted into normal mode.

Mounting Volumes Requiring Debugging

Your server is now running and you have to mount the volumes that require debug/rescue actions.

The devices of your instance are named, depending on the instance type you use. You can retrieve a list of all available devices on your instance by running the command lsblk:

NAME    MAJ:MIN RM  SIZE RO TYPE MOUNTPOINT
vda     253:0    0 18.6G  0 disk
├─vda1  253:1    0 18.5G  0 part
└─vda15 253:15   0  100M  0 part

To mount the device vda1 manually as /mnt/volume0, run the following commands:

root@scw-thirsty-ellis:~# mkdir -p /mnt/volume0
root@scw-thirsty-ellis:~# mount /dev/vda1 /mnt/volume0

You can verify the if the device has been mounted correctly, by running the lsblk command again:

NAME    MAJ:MIN RM  SIZE RO TYPE MOUNTPOINT
vda     253:0    0 18.6G  0 disk
├─vda1  253:1    0 18.5G  0 part /mnt/volume0
└─vda15 253:15   0  100M  0 part

The server is now running in rescue mode, the volume that requires debug/rescue action is mounted in the /mnt/volume0. You are now be able to perform debug/rescue actions on this volume editing files in the /mnt/volume0 folder.

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