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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 does not boot or is not available for network connection, boot it in one of the recovery and diagnostic modes. After booting, you can perform server diagnostics and correct errors in the OS configuration.

If the server becomes unavailable some time after a reboot, check if hibernation mode is enabled in the OS. Hibernation may be enabled automatically when installing some analytics packages (anaconda, cudatoolkit, nvidiautils, etc.). Example of diagnosing and disabling hibernation in Selectel blog article How to disable sleep mode in Ubuntu.

When there are problems with Mac Mini M1 and Raspberry Pi servers file a ticket.

  1. Select the recovery and diagnostic mode.
  2. Change the server load template.
  3. Connect to the server.
  4. Bring back the old server loading template.

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. It runs in the server's RAM. It is used for diagnostics, recovery and installation of Windows OS. Read more in the official Windows PE documentation.

To connect to the server in WinPE you can on VNC or through KVM console.

Rescue⁠

Rescue — recovery mode, loads the operating system in RAM without using local disks of the server. Contains pre-installed tools for system diagnostics and recovery. Install additional tools you can do it yourself using the pacman package manager.

To connect to a server in Rescue, you can over SSH or through KVM console.

The first time you authorize to the server via SSH, the SSH key is stored in the ~/.ssh/known_hosts file. If the server has been rebooted, an error may occur during re-authorization REMOTE HOST IDENTIFICATION HAS CHANGED. 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 → tab Operating system → field Login;
  • <ip_address> — the public IP address of the server. You can look in control panel under Servers and hardware → Servers → server page → tab Operating system → field IP.

Selectel Boot menu⁠

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

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

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

change the server loading template⁠

  1. In control panel go to Servers and hardware → Servers.

  2. Open the server page → tab Operating system.

  3. Click Change the upload template.

  4. In the field Upload template select to boot in one of the recovery and diagnostic modes:

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

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

Connect to the server⁠

The password for connecting to the server in recovery and diagnostic mode can be found in the control panel on the server page → tab Operating system. It is generated automatically when changing the server load pattern.

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

  • in all modes — through KVM console. An additional service can be ordered for Chipcore Line servers 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.

Return the previous server loading pattern⁠

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

  1. In control panel go to Servers and hardware → Servers.
  2. Open the server page → tab Operating system.
  3. Click Change the upload template.
  4. In the field Upload template select the previous upload template.
  5. Click Save and reboot.