Exploring vSAN HCI Mesh Help in VMware Cloud Director (VCD)

What’s vSAN HCI Mesh and its Coverage?


HCI Mesh is a particular strategy that makes use of software program to disaggregate compute and storage sources. By combining a number of autonomous vSAN clusters right into a native, cross-cluster structure, HCI Mesh permits sources to be disaggregated and stranded capability to be utilized. In essence, vSAN allows the mounting of datastores from different vSAN clusters (servers) within the vCenter stock, with out basically altering the prevailing HCI mannequin or requiring specialised {hardware}. With HCI Mesh, a cluster with surplus compute sources can now entry extra storage capability from a distant vSAN cluster.


In keeping with the coverage, a digital machine (VM) can solely be situated completely on both a distant vSAN datastore or different datastores. If the VM must be unfold throughout a number of datastores, the distant vSAN datastore can’t be included, whatever the different datastores used.

The next mixtures are usually not supported for finding digital machine information:

  1. VMFS + distant vSAN
  2. distant vSAN DS 1 + distant vSAN DS 2
  3. native vSAN + distant vSAN

Drawback Assertion

Previous to VMware Cloud Director 10.4.2, if a VMware Cloud Director storage coverage included a mixture of several types of datastores, akin to native VMFS, shared VMFS, native vSAN, or distant vSAN, the VMware Cloud Director placement engine may choose any datastore throughout the coverage to put the digital machine information and disk. Nevertheless, this posed a problem if the location engine selected a distant vSAN datastore, VMware Cloud Director didn’t essentially adhere to the vSAN HCI Mesh Coverage (distant vSAN) of retaining all digital machine information in the identical datastore, leading to scattered VM information that went in opposition to the distant vSAN insurance policies.

Other than violating the distant vSAN coverage, one other disadvantage was the potential efficiency points that would come up. If a digital machine’s disks had been scattered throughout varied varieties of datastores, particularly on distant vSAN datastore, it may result in important IOPS or latency issues with sure disks.

How the Drawback Assertion has been Resolved?

From VMware Cloud Director 10.4.2 onwards, the VMware Cloud Director VM placement engine has been enhanced to take note of the vSAN HCI Mesh Placement Coverage (distant vSAN) when inserting VMs and their information. If the location engine selects a distant vSAN datastore throughout the storage coverage, VMware Cloud Director will assure that each one VM information are saved on the identical distant vSAN datastore in accordance with the vSAN HCI Mesh placement coverage.

To accommodate totally different situations when utilizing vSAN Distant Datastore with the storage coverage that adheres to the vSAN HCI Mesh placement coverage, there are a number of superior configurations accessible. These configurations can alter the behaviour of the VMware Cloud Director VM placement engine when making selections about the place to put Digital Machine information.

  1. material.storage.placement.choose.non.distant.vsan
    • When the worth of material.storage.placement.choose.non.distant.vsan is about to true, it signifies that the administrator has instructed VMware Cloud Director to prioritize non-remote vSAN datastores throughout VM placement. On this case, VMware Cloud Director will solely use distant vSAN datastores if all different datastores are both unavailable or totally utilized.
    • Conversely, when this worth is about to false, VMware Cloud Director won’t decrease the precedence of distant vSAN datastores and can deal with them the identical as different datastores.
      • You will need to word that this flag is about to false by default.
    • CMT instructions to manage this characteristic in VMware Cloud Director: ./cell-management-tool manage-config -n material.storage.placement.choose.non.distant.vsan -v true
  2. material.storage.placement.preserve.vmdks.collectively.on.distant.vsan
    • When the worth of material.storage.placement.preserve.vmdks.collectively.on.distant.vsan is about to true, VMware Cloud Director will make an effort to put all of a digital machine’s disks (vmdks) on a single container when utilizing a distant vSAN datastore. For instance, if a distant vSAN is most popular and in accordance with the vSAN HCI mesh coverage, VMware Cloud Director will place your entire VM on that distant vSAN datastore.
    • Then again, if this worth is about to false, it signifies that VMware Cloud Director won’t adjust to the vSAN HCI Mesh VM placement coverage.
      • Please take word that this flag is about to true by default. Moreover, if a storage coverage that features a distant vSAN is getting used, this flag should all the time be set to true.
    • CMT instructions to manage this characteristic in VMware Cloud Director: ./cell-management-tool manage-config -n material.storage.placement.preserve.vmdks.collectively.on.distant.vsan-v true

On this method, VMware Cloud Director 10.4.2 has been improved by way of the way it makes use of distant vSAN datastores and the way it can adjust to the vSAN HCI Mesh Storage Placement Insurance policies.

Please be suggested that this report is meant for informational functions solely and represents our greatest effort to supply correct and helpful insights.

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