Reservation host

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In PowerVC 2.3.0, customers can allocate an entire host exclusively to a single tenant by reserving the host. In addition to the existing host group support, additional support is introduced for a reservation host group through which the hosts can be reserved. Before placing a host for reservation, make sure that the host is added to the default reservation group (Reservation > Host > Default reservation group).

Hosts that are part of the default group are considered as a viable host for reservation. You can also directly add hosts to the default reservation group during host registration.

Make sure that these conditions are met before adding a host to the default reservation group.
  • No virtual machines (VM) must be present in the host.
  • The host hypervisor must be in an 'Operating' state.
  • The host must not be in maintenance mode.
  • Custom shared processor pool (SPP) should not be present in the host.
  • If soft-pinned VMs are associated with the host, then the host cannot be used for reservation.

Considerations

Be aware of these considerations when working with reservation host.
  • Hosts present in the default reservation host group are considered as the reservation candidate.
  • Renaming and deletion of the default reservation group is not supported.
  • The default reservation group is only used for managing all the reservable hosts and does not support VM deploys.
  • A host in the reservation host group cannot be moved to 'standby mode'.
Note: To allow hosts in standby mode as reservation candidates, users can enable the show_hosts_in_standby_mode parameter in blazar.conf file. By default, the parameter is set to False. After the parameter is enabled, standby hosts that are present in the default group or custom group can be considered for host reservation.
Users with an admin role can perform these tasks.
  • Add or remove hosts to and from the default reservation group. This activity is generally performed by the project admins.
  • Create a reservation from the list of hosts in the default reservation group.
  • Add or remove hosts to or from an existing reservation.
  • Share and unshare the reservation with a secondary project.
  • Delete an existing reservation.
Note: Only admins can perform these tasks. Users with "admin-assistant" or "project-manager" roles cannot perform these tasks.

Dedicated host group

You can now reserve hosts that are available in the default reservation group. When a host is reserved, PowerVC creates a new dedicated host group, and the host is part of the new dedicated group. This host group is no different from the existing host groups that are already supported in PowerVC. Just that, these host groups and the hosts that are part of this host group are accessible only to the project in which it is created. Once a dedicated host group is created, any user in that project can perform VM deploys by using the host group ID. The dedicated host group can be viewed under the Reservation section in the PowerVC GUI. Also, users can add or remove hosts to and from an existing reservation after a dedicated host group is created

When deleting the reservation, users must make sure that all resources deployed on the hosts in the dedicated host group are cleaned up properly. Once a reservation is deleted, all hosts that are associated with the dedicated host group moves back to the default reservation group. After the last host is removed in the dedicated host group, the reservation is automatically deleted.

Considerations

Be aware of these considerations when working with dedicated host groups.
  • Dedicated hosts must be fully reserved as there is no option for partial reservation of a host.
  • Newly created dedicated host groups have 'Packing' as the default placement policy configured. After the dedicated host group is created, you can change the default placement policy to any of the supported policies from the PowerVC GUI.
  • The time at which the reservation is created is considered as the start date of the reservation. You cannot specify a future date as the start date.
  • PowerVC automatically configures the reservation end date at the time of creating the reservation. However, this can be changed later according to user specifications.
  • PowerVC supports sharing of a reservation to other projects that have users. After the reservation is shared, all the hosts that are part of the reservation becomes available to the users in the shared project.
  • Though PowerVC ensures that there are no VMs present on a host at the time of adding the host to the default reservation group, in the case of a co-managed HMC host, if there is a VM in 'shutoff' state, PowerVC assumes the VM to be a NovaLink VM and skips further validations. Users must make sure that there are no user VMs on the host before making it a reservation candidate.

Creating a reservation

To create a reservation from the available host in the PowerVC GUI, perform these steps.
  1. In the new Reservation menu, click Host, then click the Reservations tab.
  2. To create a new reservation, click Create Reservation.
  3. In the Create reservation host group page, enter a name of the reservation in the Name field, then click Next.
  4. In the Choose the host page, select the host that you want to reserve from the list of hosts that are available for reservation.

    Optionally, you can add a custom name in the Label column.

  5. In the Choose to share across the projects page, select one or more projects if you want to share the reservation with other projects. This is an optional selection. Then, click Next.
    Note: Only the owner of the host reservation can share the projects.
  6. Verify the details in the Summary page, then click Create.

    The host group is created and displays in the Reservation host groups page.

Sharing and unsharing the reservation

Administrators of a project in which a reservation is created can share and unshare the reservation with other projects.

Be aware of these considerations when sharing or unsparing reservation with other projects or a secondary project.
  • All hosts present in the reservation host group are shared with the other project or the secondary project.
  • After the reservation is shared, users from the secondary project can deploy on any host in the reservation.
  • Users from the secondary project cannot add or remove hosts from the reservation. They can neither share the reservation further to another project. They can however deploy and delete VMs.
  • Only the admins from the primary project are allowed to modify the reservation group.
  • If a reservation is shared, the user from the primary project is not allowed to delete the reservation until the resources from the shared project are cleaned up. Because the delete operation deletes the reservation and automatically cleans up the association with the secondary project.
  • There is no limit to share a particular reservation host group from the primary project.
  • The owner of the reservation is allowed to unshare the reservation from the secondary project. If the secondary project has VMs deployed, the reservation can be unshared by using the force option. This enables the users in the secondary project to continue using the VMs that they have deployed, but they will not be allowed to provision new VMs. However, deletion of the reservation from the primary project is allowed only after all resources are cleaned up, including the ones deployed from the secondary project.
  • The secondary owner of the reservation cannot unshare the reservation.
  • The primary owner can delete a shared reservation from the secondary project.

Planned and unplanned maintenance in a dedicated host group

Only project admins can perform planned or unplanned maintenance activities in a dedicated host group.

Hosts present in the default reservation group, standby hosts in the default group, and any custom host groups, irrespective of the show_hosts_in_standby_mode parameter in the blazar.conf file, can be considered as a viable host for maintenance.

If a host that is part of a dedicated host group needs to undergo planned maintenance or goes down unexpectedly, admins can choose to move the VMs to any other host in the dedicated host group or add a new host by enabling the "Maintenance Host" flag just to differentiate the host being used for maintenance against the user-reserved hosts. This attribute can be enabled or disabled from the GUI. After the maintenance is complete, admins can choose to remove the maintenance host or make the host available for users by disabling the maintenance attribute.
Note:
  • If a host that is in standby mode is added to an existing reservation as a maintenance host, the host remains in the standby mode in the reservation too.
  • Hosts that are only in the default reservation group are considered as viable hosts for maintenance in the GUI.
After the maintenance is completed, project admins can perform any of these tasks.
  • Remove the newly added host from the reservation.
    • Again migrate the VMs from the newly added host to the original host.
    • After migration, remove the host from the dedicated host group, which then automatically moves the host back to the default reservation group.
  • Make the newly added host as the primary host and remove the failed host from the reservation.
  • Remove the failed host from the reservation.

You can perform host reservation by using the Blazar service APIs. For details, see Reservation host APIs.