Maintenance Mode for Xen/KVM Compute Resources

Compute resources provide hardware for virtual servers, ensuring highly efficient use of available hardware. Below you can find the solutions regarding compute resource maintenance.

If you need to take a compute resource out of service, fix or upgrade it, use the maintenance mode feature. The VSs will be migrated to another compute resource and you can easily maintain your hardware. Be aware that after maintenance, VSs will not be migrated back to your compute resource automatically. You should  manually bring VSs back to this compute resource.

If a compute resource is overloaded, but you do not want to take it out of service, you can enable or disable the ability to install/boot virtual servers on the compute resource by means of the Enabled slider while editing compute resource. VSs, which are already created on this compute resource, will not be migrated and will be running.

  • Maintenance mode is applicable to Xen/KVM compute resources only.
  • Maintenance mode is available only for Static compute resources.
  • Ensure that the Set maintenance mode for any compute resource  permission is on before managing maintenance mode. For more information refer to the List of all OnApp Permissions section of this guide.

On this page:

Enable maintenance mode



To enable maintenance mode for a particular compute resource:

  1. Go to your Control Panel's Settings menu.
  2. Click the Compute resources icon.
  3. Click the label of the compute resource you are interested in.
  4. Click Tools > Enable Maintenance Mode.
  5. On the screen that follows:
    • move the first slider to the right if you want to stop all virtual servers that cannot be migrated to another compute resource. This might happen because there are not enough resources on other compute resources in this zone for all VSs, or there is only one compute resource in a zone.  All VSs, which have hot migration option enabled, will try to migrate to another compute resource. Also remember that smart servers can only be cold migrated.
    • move the second slider to the right if you are sure you want to enable maintenance mode for this compute resource
  6. Click Confirm. The action will be confirmed only if both options are enabled.

 

VSs will be sequentially migrated to other compute resources within the compute zone, to which your compute resource is assigned. Compute resource will be marked as in maintenance mode and you will be able to fix or upgrade it. 

Be aware, that Xen-based VSs are migrated to Xen compute resources, and KVM- based VSs - to KVM compute resources respectively within one compute zone. If you want to enable maintenance mode for Xen compute resource, there must be at least one more Xen compute resource within compute zone, to which both of them are assigned. Otherwise you will not be able to activate maintenance mode for this compute resource.

 

Disable maintenance mode


 

To bring a compute resource back online, switch maintenance mode off:

  1. Go to your Control Panel's Settings menu.
  2. Click the Compute resources icon.
  3. Click the label of the compute resource you are interested in.
  4. Click Tools > Disable Maintenance Mode.

If you want to return VSs to the compute resource, from which they were migrated,  you should  manually bring VSs back to this compute resource.

Disabling maintenance mode initiates automatic compute resource reboot.


Maintenance mode and CPU flags


 

If the compute zone has already configured CPU flags, and then one of the compute resources of this compute zone goes to maintenance mode, there are several scenarios when it goes back online:

  • if the compute resource after maintenance has the same CPU flags as all other compute resources in a compute zone, the performance stays on the previous level and no problems should occur.
  • if the compute resource after maintenance has more flags than other compute resources in a compute zone, the additional flags will not be enabled for this compute zone.
  • if the compute resource after maintenance has less flags and worse performance than other compute resources in a compute zone, you will receive the email that there is an inconsistency with the flags and the warning that the current configuration of a compute zone is broken with the recommendation to fix that on CPU Flags page for a compute zone.