Using Maintenance Mode

If you need to take a compute module offline for service, you place it into maintenance mode.

Note: This topic discusses maintenance mode on a ztC Endurance system. Do not confuse it with maintenance mode on an ESXi host; they are unrelated operations. For information about placing an ESXi host into maintenance mode, read this discussion in the VMware documentation.

When you place a compute module into maintenance mode, it goes offline for service. While a compute module is in maintenance modeClosed A ztC Endurance state that takes a module offline so that it can be serviced., operations such as monitoring, recovery, automatic power-on, and so on cannot occur on that compute module.

If you place the active compute module into maintenance mode, the system automatically performs a Smart ExchangeClosed A proprietary process that maintains system availability and protects against data loss. If the ztC Endurance system detects a degradation or failure within the active compute module, Smart Exchange: 1) Automatically activates the standby compute module and copies over in-process data. 2) Reroutes all I/O and storage connected to the original active compute module to the newly activated compute module. Smart Exchange occurs while the system is running and, except for a very brief pause (usually less than one second), is undetectable to the operating system and customer applications.​.

Smart Exchange​ is a Stratus proprietary process that maintains system availability and protects against data loss. If the ztC Endurance system detects a degradation or failure within the active compute module, Smart Exchange​:

  • Automatically activates the standby compute module and copies over in-process data

  • Reroutes all I/O and storage connected to the original active compute module over to the newly activated compute module

Smart Exchange​ occurs while the system is running and except for a very brief pause (usually, less than one second), is undetectable to the operating system and customer applications.

You must manually remove the compute module from maintenance mode to return it to service.

Note that when the active compute module enters maintenance mode, the standby compute module becomes active after the Smart Exchange completes. During this operation, communications between the active and standby compute modules are disabled, and the operating system and VMs running on the original active compute module are migrated to the new active compute module. This protects the operating system and running VMs from any potential disruption caused by the operation.

Notices:  

  1. A compute module must be in maintenance mode before you shut it down. For information about shutting down a compute module, see Shutting Down and Restarting a Compute Module.

  2. The system is not fault tolerant when a compute module is in maintenance mode. For continuous uptime, finalize service as soon as possible so that the compute module can exit maintenance mode and go back online.

To place a compute module into maintenance mode

  1. From the Hardware page, select a compute module.

  2. Click Work On.

  3. Click Yes on the Confirm window.

    When the compute module is in maintenance mode, its state appears as Maintenance Mode, and its Activity displays as Running. At this point, it is safe to shut down the compute module if necessary.

To remove a compute module from maintenance mode

  1. From the Hardware page, select the compute module that is in maintenance mode.

  2. Click Finalize, which removes the compute module from maintenance mode.

    When the compute module exits maintenance mode, its state appears as Normal, and its Activity displays as Running.

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