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Boot the server in recovery and diagnostic mode
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Boot the server in recovery and diagnostic mode

If the server fails to boot, or is not available for network connectivity, boot it in one of the recovery and diagnostic modes. After booting, you can run server diagnostics and fix errors in the OS configuration.

If the server becomes unavailable some time after rebooting, check if hibernation mode is enabled in the OS. Hibernate can be enabled automatically when installing some analytics packages (anaconda, cudatoolkit, nvidiautils, etc.). An example of troubleshooting and disabling hibernation is in the Selectel blog article How to Disable Hibernation in Ubuntu.

For problems with Mac Mini M1 servers, create a ticket.

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

1. Select recovery and diagnostic mode⁠

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

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

WinPE⁠

WinPE is a minimal version of Windows with limited services. Runs in the server's RAM. Used to diagnose, repair, and install Windows operating systems. See official Windows PE documentation for more information.

You can connect to the server in WinPE via VNC or via KVM-console.

Rescue⁠

Rescue — recovery mode, loads the operating system in RAM without using the server's local disks. Contains pre-installed system diagnostic and recovery tools. Additional tools can be installed independently via the pacman package manager.

You can connect to the server in Rescue via SSH or via KVM-console.

When you first authorize to the server via SSH, the SSH key is stored in the ~/.ssh/known_hosts file. If the server has been rebooted, a REMOTE HOST IDENTIFICATION HAS CHANGED error may appear when re-authorizing. To fix it, remove the host information by IP address:

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

Specify:

  • <username> — user name (login). You can look in Control Panel under Servers and Hardware → Servers → Server page → Operating System tab → Login field;
  • <ip_address> is the public IP address of the server. You can look in Control Panel under Servers and Hardware → Servers → Server page → Operating System tab → IP field.

Selectel Boot menu⁠

Selectel Boot — menu for system diagnostics and recovery, booting the most common server operating systems. Diagnostic and recovery tools are available in the Tools and Utilities section:

  • GParted — disk creation and partitioning;
  • Clonezilla — creating backups. For UEFI servers, use an image mounted through a KVM console;
  • Memtest86 — RAM testing.

To use the Selectel Boot menu, connect to the server via KVM-console.

2. Change the server loading template⁠

  1. In Control Panel, go to Servers and Hardware → Servers.

  2. Open the server page → Operating System tab.

  3. Click Change Upload Template.

  4. In the Boot Template field, select boot in one of the recovery and diagnostic modes:

  5. In the New Password field, click . A new password will be generated. It is only used to connect to the server in recovery and diagnostic mode.

  6. Click Save and Reload. The server will be rebooted and all data on it will be saved.

3. Connect to the server⁠

The password for connecting to the server in recovery and diagnostic mode can be viewed in Control Panel on the server page → Operating System tab. It is generated automatically when change-server-boot-template.

The connection process depends on the selected recovery and diagnostic mode.

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

4. Bring back the old server loading template⁠

When the server is rebooted from the OS, the boot template will automatically change to the one that was set before change-server-boot-template.

  1. In Control Panel, go to Servers and Hardware → Servers.
  2. Open the server page → Operating System tab.
  3. Click Change Upload Template.
  4. In the Upload Template field, select the previous upload template.
  5. Click Save and Reload.