Host standby mode

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Starting PowerVC 2.2.0, you can move a host to standby mode. A Standby host is also referred to as a reserve-on-purpose host.

Before placing a host in standby mode, these conditions must be met.
  • The host's hypervisor must be in an “operating” state.
  • No virtual machine (VM) must be present in the host.
  • If soft pinned VMs are associated with the host, that host cannot be placed into a standby mode.
Hosts in standby mode can be associated with one of the three tags based on the requirement of the administrator.
  • Provisioning - A standby host that is tagged as provisioning can be used for virtual machine deployments if there are no other viable hosts available in the host group. The standby hosts with this tag can also be used to remote restart the virtual machines if there is an unplanned maintenance activity, for example, an automated remote restart activity.
  • Planned Maintenance - A standby host that is tagged for planned maintenance can only be used to migrate virtual machines from a host that is moved to the host maintenance mode for performing maintenance activity.
  • Unplanned Maintenance - A standby host that is tagged for unplanned maintenance can only be used to perform evacuation of virtual machines from a failed host.
Note: Both active and inactive migrations of VMs to a standby host are restricted. Any targeted mobility operation of the VM to the standby host fails.
A host in standby mode exits the standby mode automatically in these instances.
  • When the standby host is selected by the scheduler for performing the activity based on the standby tag.
  • If VMs are deployed out of band on to the standby host.
  • If VMs are migrated out of band to the standby host.
Administrators can perform these tasks.
  • Unset the standby host to ‘Available’.
  • Define the standby mode during the registration of the new host.
  • Define any number of hosts as standby hosts and these hosts will not be considered as viable hosts for any policy set at the host group level, for example, Packing, Striping, CPU or Memory balance, and so on.
  • Administrators can also add a host to standby mode in any host group of their choice based on the business needs.

Moving a host to standby mode in the PowerVC GUI

To move a host to standby mode in PowerVC GUI, perform these steps.
  1. In the Hosts menu, click Add hosts to open the Add hosts page.
  2. Select HMC as the Host management type, then the HMC name.
  3. In the host list table, select the host and in the new Standby column, and then change the toggle option to On to move the selected host to standby mode.
  4. Tag the host to standby mode by selecting any of these operations from the drop-down.
    • Provisioning
    • Planned Maintenance
    • Unplanned Maintenance
      Note:
      • The default selection is Unplanned Maintenance
      • If there is a standby host that is tagged for unplanned maintenance in the host group, it is selected for the automated remote restart (ARR) of VMs even if there is capacity available on the hosts that are not in standby mode.
  5. Click Add Host.

    In the Host List page, the State column displays the 'Standby On' status and the new Standby tag column displays the operation that is selected for the standby host.

  6. Click the host to open the host edit page. The new Standby tag drop-down provides you with an option to make changes to your initial operation in the host edit page.
    Note: The Standby tag drop-down only displays when the host is selected to standby mode.
  7. Alternatively, you can also change the standby tag in the Enter standby window by using these steps.
    1. In the Host list page, select the host, then click Enter standby mode.
    2. In the Enter Standby window, select the operation in the Standby tag drop-down.
    3. Select the host radio button, then click Enter standby.
Hosts that are placed in standby mode do not display in the following pages in the GUI.
  • Host drop-down in the Deploy VM page.
  • Destination drop-down in the Enter Maintenance window in the Host list page. If the host that is placed in standby mode is tagged as planned maintenance, the host displays in the Destination drop-down.
  • Destination drop-down in the Remote restart VMs page. If the host that is placed in standby mode is tagged as unplanned maintenance or provisioning, the host displays in the Destination drop-down.

The host standby mode API allows to enable or disable the host standby mode for a specific host. For details, see Host standby mode.