Host Operations

You can perform the following operations on a host:
  • Add host: Add a new host.
  • Enable: Enable the host that you selected.
  • Disable: Disable the host that you selected.
    Note: After you disabled a host successfully, the existing resources on the host will not be affected, but the host cannot serve as a candidate host to apply for new resources.
  • Reconnect: Reconnect the host that you selected.
    Note:
    • Generally, the reconnect operation is performed after you update the configurations of the host.
    • For example, after you update the memory or hard disk of the host, you can reconnect the host to update your database.
  • Bind tag: Bind a tag to the host.
    Note:
    • Hosts can only bind admin tags.
    • One resource can bind 50 tags at most, while a single tag can bind the unlimited number of resources.
    • Many-to-many bindings between tags and resources are supported. That is, you can bind multiple tags to multiple resources.
    • Tags that were created by a tenant can only be bound to resources owned by the tenant, while admin tags can be bound to all resources.
    • An administrator can unbind or delete tenant tags.
    • Resource tags can be sorted in order according to the creation time or tag names (priority: characters > numbers > Chinese characters > English characters). To change the sort order, choose Settings > Global Settings > Advanced, locate Tag sorting field, and click the Edit icon. By default, the tags are sorted in order by the tag name.
  • Unbind tag: Unbind a tag from the host.
    Note:
    • Multiple tags on a single resource can be unbound simultaneously. In addition, multiple resources on a single tag can also be unbound simultaneously.
    • A tenant can only unbind tags from the resources owned by the tenant itself, while an administrator can unbind tags from all resources.
  • Enter maintenance mode: Place the host in maintenance mode. In this mode, you can stop and repair the host.
    • If a host is running on a local storage primary storage, VM instances that are running on the host will be stopped after the host enters maintenance mode.
    • If a host is running on a shared storage, VM instances that are running on the host will be migrated automatically after the host enters maintenance mode.
    Note:
    • Under the shared storage scenario, after the host enters maintenance mode, you can set the VM migration policy in case of migration failure.
    • Method:
      Go to Settings > Global Settings > Advanced, locate host.maintenance.policy, and click the Edit icon.
      • If you select Stop Vm On Migration Failure, VM instances that are running on a shared storage will be automatically migrated to other hosts after the host where the VM instances reside enters maintenance mode. In addition, VM instances that fail to be migrated will be forced to stop.
      • If you select Just Migrate, VM instances that are running on a shared storage will be automatically migrated to other hosts after the host where the VM instances reside enters maintenance mode. If some VM instances are still running on the host, the host will fail to enter maintenance mode.
  • Delete: Delete the host that you selected.
    Note:
    • If you delete a host, all VM instances that are running on the host will be stopped.
    • Local storage primary storage scenario:
      • If the cluster where the host belongs is attached to a LocalStorage primary storage, all VM instances and volumes on this host will be deleted as well. Please exercise caution.
      • Even if you add a deleted host to the cloud again, the system will deploy this host again. If the previous database resource is not backed up, associated business data will not be recovered.
    • Shared storage scenario:
      • Assume that the HA Level on VM instances is set to None.

        After you delete the host where the VM instances belong, the corresponding VM instances will be stopped.

      • Assume that the HA Level on VM instances is set to NeverStop.
        If resources of other hosts permit, the VM instances with the NeverStop HA level and running on this host will be stopped firstly after you delete the host. Next, these VM instances will be migrated to other hosts and then automatically start without affecting your data security. If resources on these hosts are insufficient, the corresponding VM instances will be stopped.
        Note: Under this circumstance, a portion of VM instances might be migrated to other hosts with sufficient resources, while another portion of VM instances might be stopped due to a shortage of host resources.
      • If you delete the host, data volumes on the shared storage will not be affected.
    • Assume that you have installed the Migration Service module license. If the host is specified as a conversion host, the corresponding conversion host will be deleted as well after the host is deleted. In addition, an on-going V2V migration job on this conversion host will be automatically canceled. Please exercise caution.