Knowledgebase / FAQ - ip-connect GmbH

1. (Zuletzt geändert von rsch an 26.12.2010 16:52:31)

Tech Support Mode for Emergency Support

Details

This article provides information about ESXi 3.5 or 4.0 Tech Support Mode.

For information about ESXi 4.1 Tech Support Mode, see Using Tech Support Mode in ESXi 4.1 (1017910).

Solution

Tech Support Mode provides a command-line interface that can be used to diagnose and repair VMware ESXi hosts.

Warning: Tech Support Mode should only be used at the request of VMware technical support.

Tech Support Mode is:

Enabled in ESXi 3.5 and ESXi 4.0 for default VMware ESXi installations
Only usable with physical access to the server console and root privileges
Unsupported unless used in consultation with VMware Tech Support.

For example, VMware technical support might instruct a customer to use Tech Support Mode to restart management agents when these agents cannot be restarted through the Direct Console UI (DCUI). After completing any tasks that require the use of Tech Support Mode, all subsequent diagnostics would then be performed through the remote interfaces. Use of Tech Support Mode can be controlled by restricting physical access to servers, limiting access to the root password or disabling the feature entirely.

Customers should be aware of current limitations of Tech Support Mode that may violate corporate security policies or best practices:

The interface is not audited, so commands issued at this interface are not logged.
Commands that can be issued from this interface can result in an unusable system.
The interface only supports logging in as root. No other user account or role can use this management interface.

It is for these reasons that VMware only supports the use of Tech Support Mode as a last resort to troubleshooting an ESXi host. As a result, customers should expect to use the Direct Console UI (DCUI), Remote Command Line Interface (RCLI), or the VI Client as available alternatives to accessing the host through the Tech Support Mode.

ESXi 3.5 or 4.0

To use Tech Support Mode:

Log in to your ESXi host at the console.
Press Alt+F1 to switch to the console window.
Enter unsupported to start the Tech Support Mode login process. Note that no text will appear on the console window.
Enter the password for the root user. Tech Support Mode is now active.
Complete tasks in Tech Support Mode.
Enter the command clear to clear the screen of any residual data from step 5. This may be required by your local security policies.
Enter the command exit to exit Tech Support Mode.
Press Alt+F2 to return the server to DCUI mode.

Enabling Tech Support Mode and attempting to log in to Tech Support Mode, whether successful or unsuccessful, is logged in the syslog. Activity performed within Tech Support Mode is not logged.

Tech Support Mode is one of the many tools that VMware provides to diagnose and repair problems with ESXi hosts without incurring virtual machine downtime in most cases.

Administrators can disable or re-enable Tech Support Mode on each host by modifying advanced configuration parameters. Each time the setting for supporting Tech Support Mode is changed, you must reboot the host before the setting takes effect.

To disable Tech Support Mode:

Connect VMware Infrastructure Client (VI Client) to an ESXi host or a VirtualCenter Server.
Browse to a host in the inventory list.
Click the Configuration tab.
Click the Advanced Settings link.
Click VMkernel in the left-hand pane.
In the list of parameters, deselect VMkernel.Boot.techSupportMode.
Restart the ESXi host. Before restarting the host, you should shut down virtual machines on that host or migrate them to another host using vMotion or cold migration.

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