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

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What is vSAN HCI Mesh and its Coverage?


HCI Mesh is a unique method that makes use of software to disaggregate compute and storage sources. By combining several autonomous vSAN clusters into a indigenous, cross-cluster architecture, HCI Mesh makes it possible for resources to be disaggregated and stranded ability to be utilized. In essence, vSAN permits the mounting of datastores from other vSAN clusters (servers) in the vCenter inventory, without having fundamentally altering the present HCI model or requiring specialized hardware. With HCI Mesh, a cluster with surplus compute assets can now accessibility additional storage capacity from a remote vSAN cluster.


In accordance to the coverage, a digital machine (VM) can only be found completely on both a remote vSAN datastore or other datastores. If the VM requires to be unfold throughout various datastores, the remote vSAN datastore cannot be involved, no matter of the other datastores made use of.

The pursuing combinations are not supported for finding virtual equipment information:

  1. VMFS + distant vSAN
  2. remote vSAN DS 1 + distant vSAN DS 2
  3. community vSAN + distant vSAN

Dilemma Assertion

Prior to VMware Cloud Director 10.4.2, if a VMware Cloud Director storage coverage provided a blend of unique styles of datastores, these as nearby VMFS, shared VMFS, area vSAN, or distant vSAN, the VMware Cloud Director placement engine could choose any datastore in the policy to place the digital machine information and disk. Even so, this posed a obstacle if the placement engine chose a distant vSAN datastore, VMware Cloud Director did not necessarily adhere to the vSAN HCI Mesh Policy (distant vSAN) of retaining all digital machine data files in the very same datastore, ensuing in scattered VM documents that went against the remote vSAN insurance policies.

Aside from violating the distant vSAN coverage, a different disadvantage was the probable efficiency concerns that could come up. If a digital machine’s disks had been scattered across several varieties of datastores, particularly on remote vSAN datastore, it could direct to substantial IOPS or latency troubles with sure disks.

How the Issue Statement has been Solved?

From VMware Cloud Director 10.4.2 onwards, the VMware Cloud Director VM placement engine has been improved to acquire into account the vSAN HCI Mesh Placement Coverage (distant vSAN) when putting VMs and their information. If the placement engine selects a remote vSAN datastore inside of the storage coverage, VMware Cloud Director will guarantee that all VM data files are stored on the similar remote vSAN datastore in accordance with the vSAN HCI Mesh placement coverage.

To accommodate unique scenarios when applying vSAN Remote Datastore with the storage coverage that adheres to the vSAN HCI Mesh placement plan, there are various sophisticated configurations out there. These configurations can change the conduct of the VMware Cloud Director VM placement motor when making conclusions about in which to position Virtual Machine documents.

  1. material.storage.placement.prefer.non.remote.vsan
    • When the price of material.storage.placement.prefer.non.distant.vsan is established to accurate, it suggests that the administrator has instructed VMware Cloud Director to prioritize non-remote vSAN datastores for the duration of VM placement. In this circumstance, VMware Cloud Director will only use remote vSAN datastores if all other datastores are possibly unavailable or totally utilized.
    • Conversely, when this value is set to untrue, VMware Cloud Director will not reduced the precedence of distant vSAN datastores and will treat them the exact as other datastores.
      • It is significant to observe that this flag is set to bogus by default.
    • CMT instructions to control this feature in VMware Cloud Director: ./cell-administration-instrument deal with-config -n material.storage.placement.prefer.non.remote.vsan -v correct
  2. cloth.storage.placement.continue to keep.vmdks.together.on.distant.vsan
    • When the benefit of fabric.storage.placement.preserve.vmdks.together.on.distant.vsan is established to accurate, VMware Cloud Director will make an work to position all of a virtual machine’s disks (vmdks) on a one container when using a remote vSAN datastore. For illustration, if a distant vSAN is preferred and in accordance with the vSAN HCI mesh policy, VMware Cloud Director will location the overall VM on that distant vSAN datastore.
    • On the other hand, if this worth is established to bogus, it suggests that VMware Cloud Director will not comply with the vSAN HCI Mesh VM placement plan.
      • Please just take observe that this flag is established to true by default. On top of that, if a storage coverage that features a remote vSAN is remaining utilized, this flag need to constantly be established to true.
    • CMT instructions to management this characteristic in VMware Cloud Director: ./mobile-management-resource handle-config -n material.storage.placement.hold.vmdks.jointly.on.distant.vsan-v true

In this manner, VMware Cloud Director 10.4.2 has been enhanced in phrases of how it utilizes distant vSAN datastores and how it can comply with the vSAN HCI Mesh Storage Placement Insurance policies.


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