This mode allows to restore the server's operation if the server is unable to start after reboot, or no remote connection is available. One of the templates is loaded from the location to the server when recovery starts. Template is a LiveCD image of the operating system SystemRescueCD. This OS is intended for maintenance, diagnostics and debugging of the server. Read more about SystemRescueCD in the official documentation.

Preparing the server for recovery


Server can be recovered if:

  • a Linux family OS is installed;
  • network boot function via iPXE or PXE is configured.

We recommend configuring the server connection to a BMC (Intel AMT) or PDU. If the connection is not configured, the server will need to be rebooted manually to start the operation.

Make sure that the recovered server is in the same L2 network segment with the location server, and DHCP, TFTP and HTTP traffic is allowed on this segment.

Prior to starting the recovery, install recovery templates onto the server's location. Read more in How to add a location.

Recovery mode start


To run server recovery mode:

  1. Go to Servers → select server → Run recovery.
  2. Select the Recovery template:
    • Sysrescd6-x86_64 a recommended template based on SystemRescue CD 6;
    • FreeBSD-rescue-amd64 — for FreeBSD OS;
  3. Select Server boot mode. If the server supports only one of the network boot modes, select a required one: PXE or iPXE. If both variants are supported, we recommend that you use the one set by the operation template per default.
  4. Press Run.
  5. Enter Server administrator password.
  6. If the server is not configured to connect to a PDU, BMC or Intel AMT, reboot the server manually.

After the start of operation, DCImanager will proceed to load the selected recovery template to the server. The template loading process is displayed at Servers page in Status column. After completion of loading, you can connect to the server via SSH with superuser permissions using the password you have created.

Recovery mode canceling


To exit recovery mode, go to Servers → select the server → Cancel the current operation → Cancel recovery. The server will reboot automatically. If the server is not configured to connect to a PDU, BMC or Intel AMT, reboot the server manually.

Example of the superuser password recovery on the server


  1. Connect to the server, loaded with the recovery template via SSH.
  2. Specify the drives connection method. For instance wit the command:

    lsblk
    BASH
  3. Define the root directory.
  4. Create the directory:

    mkdir /true_root
    BASH
  5. Mount the root directory:

    mount /dev/device /true_root
    BASH

    Where:

    • device — device of a root directory

  6. Change the root directory:

    chroot /true_root
    BASH
  7. To change the superuser password, run:

    passwd root
    BASH
  8. Insert the new password twice and exit the chroot with:

    exit
    BASH
  9. Unmount the directory:

    umount /true_root
    BASH