You can configure low disk space thresholds on a storage container to receive an email from VMware Cloud Director when the datastore reaches a specific threshold of available capacity. These warnings alert you to a low disk situation before it becomes a problem.

There are two datastore thresholds in VMware Cloud Director.
  • Red threshold - the amount of free space on a datastore, below which, VMware Cloud Director filters out the datastore during the placement of any entity such as a VM, a template, or a disk.

    When a datastore reaches its red threshold, the workload placement engine stops placing new VMs on the datastore except while importing VMs from vCenter Server. In the case of VM import, if the vCenter Server VM is already present on the red threshold datastore, the placement engine prefers the existing datastore.

    The workload placement engine uses the red threshold for all workflows. When making a request for any new placement, the placement engine first filters out any datastores or storage pods which have breached the red threshold. When making a placement request for an existing entity, if the disks are residing on the datastores that are breaching the red threshold, VMware Cloud Director relocates the disks to other available datastores. Then, the engine selects a datastore out of the remaining datastores or storage pods, either through the selector logic of VMware Cloud Director or from the vSphere Storage DRS recommendations.

  • Yellow threshold - the amount of free space on the datastore, below which VMware Cloud Director filters out the datastore during the placement of shadow VMs from which VMware Cloud Director creates fast-provisioned VMs. For more information on shadow VMs, see Fast Provisioning of Virtual Machines.

    The yellow threshold does not apply to the linked clones that VMware Cloud Director uses for fast provisioning of VMs. When the placement engine selects a datastore for a linked clone, if the selected datastore is missing a shadow VM, VMware Cloud Director creates a shadow VM on the datastore. The threshold does not apply to the shadow VM in this case.

    The yellow threshold applies only to the periodic background job creating shadow VMs. If activated, the job runs every 24 hours and uses eager VM creation on each datastore for a given hub and storage policy pair. To activate the job for eager provisioning of shadow VMs, you must set the following property to true. 
    valc.catalog.fastProvisioning=true
    Note: The periodic background job creates shadow VMs on all datastores for all templates. The job increases the storage consumption even when you are not using the datastores or shadow VMs.

When implementing the threshold logic, VMware Cloud Director does not evaluate the requirements of the current placement subject. For the workload placement engine to place a subject on a datastore, the available space in bytes must be more than the threshold in bytes. For example, for a datastore with available capacity of 5 GB with a red threshold set at 4 GB, the placement engine can place a VM with a requirement for 2 GB. If the VM creation breaches the threshold, the placement engine filters out the datastore for further placements.

When you set thresholds on a stand-alone datastore, they apply only to that datastore. If you set thresholds on a datastore cluster, they apply to all datastores in the cluster. By default, VMware Cloud Director sets the red threshold to 15% and the yellow threshold to 25% of the stand-alone datastore or the datastore cluster's total capacity.

Because the default thresholds on a datastore cluster are based on the total cluster capacity, the thresholds might exceed the capacity of individual datastores within the cluster. When setting thresholds on a datastore cluster, consider the capacity of each datastore in the cluster and set thresholds manually rather than accepting the default threshold configurations.

Procedure

  1. From the top navigation bar, select Resources and click Cloud Resources.
  2. In the left panel, select Provider VDCs, and click the name of the target provider virtual data center.
  3. Select the Storage Containers tab.
  4. Click the name of a storage container and click Edit.
  5. Select the disk space thresholds for the storage container.
  6. Click Save.

Results

VMware Cloud Director sets the thresholds for all provider virtual data centers that use the datastore. VMware Cloud Director sends an email alert when the datastore crosses the threshold. When a datastore reaches its red threshold, the virtual machine placement engine stops placing new virtual machines on the datastore except for already-placed imported VMs.