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Boot the server in recovery and diagnostic mode

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If the server does not boot or is unreachable over the network, boot it in one of the recovery and diagnostic modes. After booting, you can perform server diagnostics and fix OS configuration errors.

If the server becomes unreachable after some time following a reboot, check if hibernation is enabled in the OS. Hibernation can be enabled automatically when installing certain analytics packages (anaconda, cudatoolkit, nvidiautils, etc.). An example of how to diagnose and disable hibernation is in the Selectel blog article How to disable hibernation in Ubuntu.

For issues with Mac Mini M1 and Raspberry Pi servers, create a ticket.

  1. Select a recovery and diagnostic mode.
  2. Change the server boot template.
  3. Connect to the server.
  4. Return to the previous server boot template.

1. Select a recovery and diagnostic mode

Recovery and diagnostic modes provide full access to the server file system.

We recommend using a recovery and diagnostic mode based on your tasks and server OS:

  • Rescue — for Linux servers;
  • WinPE — for Windows servers;
  • Boot menu — for any server OS;
  • Veeam Recovery Media 13 for Windows — for restoring a server from a backup;
  • Talos — for working with Kubernetes.

Rescue is a recovery mode that loads the operating system into RAM without using the server's local disks. It contains pre-installed system diagnostics and recovery tools. You can install additional tools yourself via the pacman package manager.

You can connect to a server in Rescue mode via SSH or a KVM console.

When you first authenticate on the server, the SSH key is saved to the ~/.ssh/known_hosts file. If the server has been rebooted, the error REMOTE HOST IDENTIFICATION HAS CHANGED may occur upon re-authentication. To fix it, delete the host information for the IP address:

ssh-keygen -f "/home/<username>/.ssh/known_hosts" -R "<ip_address>"

Specify:

  • <username> — username (login). You can view it in the control panel: in the top menu, click ProductsDedicated ServersServers → server page → Operating System tab → Login;
  • <ip_address> — public IP address of the server. You can view it in the control panel: in the top menu, click ProductsDedicated ServersServers → server page → Operating System tab → IP.

2. Change the server boot template

  1. In the control panel, on the top menu, click Products and select Dedicated Servers.

  2. In the Servers section, open the server page → Operating System.

  3. Click Change boot template.

  4. Select a boot template:

    • Boot to Rescue;
    • Boot to WinPE;
    • Boot to Boot menu;
    • Boot to Veeam Recovery Media 13 for Windows;
    • Boot to Talos.
  5. In the New password field, click . A new password will be generated; it is used only for connecting to the server in recovery and diagnostics mode.

  6. Click Save and reboot. The server will be rebooted, and all data on it will be preserved.

3. Connect to the server

The password for connecting to the server in recovery and diagnostics mode can be viewed in the control panel in the ProductsDedicated ServersServers → server page → Operating System tab. This password was generated when changing the server boot template in step 5.

The connection process depends on the selected recovery and diagnostics mode:

  • in all modes — via the KVM console. For Chipcore Line servers, you can order the additional IP-KVM access for 3 hours service;
  • in Rescue — via SSH — to protect servers from attacks, the number of authorization attempts when connecting to a server in Rescue mode is limited. If there are 10 failed connection attempts from one IP address within an hour, this IP address will be blocked for 24 hours. To unblock the IP address earlier, reboot the server;
  • in WinPE — via VNC;
  • in Veeam Recovery Media 13 for Windows — VNC;
  • in Talos — VNC.

4. Return to the previous server boot template

When rebooting the server from the OS, the boot template will automatically change to the one that was set before changing the server boot template.

  1. In the control panel, on the top menu, click Products and select Dedicated Servers.
  2. In the Servers section, open the server page → Operating System.
  3. Click Change boot template.
  4. In the Boot template field, select the previous boot template.
  5. Click Save and reboot.