What is vSAN HCI Mesh and its Policy?
Definition:
HCI Mesh is a particular method 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 permits the mounting of datastores from different vSAN clusters (servers) within the vCenter stock, with out basically altering the present 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.
Policy:
According to the coverage, a digital machine (VM) can solely be positioned fully 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 following combos are usually not supported for finding digital machine recordsdata:
- VMFS + distant vSAN
- distant vSAN DS 1 + distant vSAN DS 2
- native vSAN + distant vSAN
Problem Statement
Prior to VMware Cloud Director 10.4.2, if a VMware Cloud Director storage coverage included a mixture of various kinds of datastores, resembling native VMFS, shared VMFS, native vSAN, or distant vSAN, the VMware Cloud Director placement engine might choose any datastore inside the coverage to position the digital machine recordsdata and disk. However, this posed a problem if the position engine selected a distant vSAN datastore, VMware Cloud Director didn’t essentially adhere to the vSAN HCI Mesh Policy (distant vSAN) of holding all digital machine recordsdata in the identical datastore, leading to scattered VM recordsdata that went towards the distant vSAN insurance policies.
Apart from violating the distant vSAN coverage, one other downside 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 might result in important IOPS or latency issues with sure disks.
How the Problem Statement has been Resolved?
From VMware Cloud Director 10.4.2 onwards, the VMware Cloud Director VM placement engine has been enhanced to have in mind the vSAN HCI Mesh Placement Policy (distant vSAN) when putting VMs and their recordsdata. If the position engine selects a distant vSAN datastore inside the storage coverage, VMware Cloud Director will assure that each one VM recordsdata are saved on the identical distant vSAN datastore in accordance with the vSAN HCI Mesh placement coverage.
To accommodate completely different situations when utilizing vSAN Remote 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 position Virtual Machine recordsdata.
- material.storage.placement.want.non.distant.vsan
- When the worth of material.storage.placement.want.non.distant.vsan is ready to true, it signifies that the administrator has instructed VMware Cloud Director to prioritize non-remote vSAN datastores throughout VM placement. In 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 ready to false, VMware Cloud Director is not going to decrease the precedence of distant vSAN datastores and can deal with them the identical as different datastores.
- It is vital to notice that this flag is ready to false by default.
- CMT instructions to manage this function in VMware Cloud Director:
./cell-management-tool manage-config -n material.storage.placement.want.non.distant.vsan -v true
- material.storage.placement.maintain.vmdks.collectively.on.distant.vsan
- When the worth of material.storage.placement.maintain.vmdks.collectively.on.distant.vsan is ready to true, VMware Cloud Director will make an effort to position 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 all the VM on that distant vSAN datastore.
- On the opposite hand, if this worth is ready to false, it implies that VMware Cloud Director is not going to adjust to the vSAN HCI Mesh VM placement coverage.
- Please take notice that this flag is ready to true by default. Additionally, if a storage coverage that features a distant vSAN is getting used, this flag should at all times be set to true.
- CMT instructions to manage this function in VMware Cloud Director:
./cell-management-tool manage-config -n material.storage.placement.maintain.vmdks.collectively.on.distant.vsan-v true
In this fashion, 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 Policies.
Please be suggested that this report is meant for informational functions solely and represents our greatest effort to supply correct and helpful insights.