VMware vSAN HCI Mesh

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VMware vSAN HCI Mesh

The Scale-out architecture of VMware vSAN enables powerful non-disruptive scale-up or scale-out capabilities. You can non-disruptively expand capacity and performance by adding hosts to a cluster (scale-out) or just grow capacity by adding disks to a host (scale-up). As application workloads organically grow, this enables performance to be right-sized at each expansion interval. Over time the ratio of storage and compute can be right-sized through vSAN. Despite this, inorganic scale events can prove challenging to any architecture. Examples include:

  • An application refactor requires significant storage to be added for logs.
  • A new line of business for analytics may consume excessive compute, potentially stranding storage assets.
  • M&A may result in new business units bringing unforeseen storage requirements to a cluster.
  • The deployment of Networking Virtualization, powered by NSX, has enabled the migration and consolidation of legacy stranded cluster resources.

Historically, when these scaling events happen it could cause an existing cluster to run out of storage or compute and potentially strand the lower demanded resource. While vMotion enables “Shared nothing migration” between clusters, this still forced storage and compute to move together between clusters.
Traditional storage have had methods of solving this challenge, but the results were often underwhelming. Array virtualization solved this problem by proxying storage through an additional array. This allowed for consolidation of stranded storage resources, but resulted in added latency, complexity, support costs as administrators were forced to use multiple user interfaces and tools for basic operational tasks and troubleshooting. For these reasons a different approach was chosen.

Fig.: vSAN HCI Mesh

How does VMware vSAN HCI Mesh work?

To solve these Challenges, VMware has introduced VMware HCI Mesh.

HCI Mesh is a unique, software-based approach for disaggregation of compute and storage resources. HCI Mesh brings together multiple independent vSAN clusters for a native, cross-cluster architecture that disaggregates resources and enables utilization of stranded capacity. Simply, vSAN allows one or more vSAN clusters to remotely mount datastores from other vSAN clusters (servers) within vCenter inventory. This approach maintains the essence and simplicity of HCI by not fundamentally changing the existing HCI model or requiring specialized hardware. Now, a cluster with excess compute can mount excess storage from a remote vSAN cluster.

Setup is easy, with built-in health checks to verify the configuration is healthy and supported.

The vSAN performance service has added a “Remote VM” tab to allow visibility end to end for virtual machines that are stored on a remote vSAN cluster.

VMware vSAN HCI Mesh

This connectivity brings increased storage efficiencies, while avoiding the support and operational complexities that are more commonly affiliated with storage virtualization. The built in vSAN health checks, performance monitoring services, and policy-based management remain intact to the VMware administrator.

What is it?

HCI Mesh works by using the existing vSAN VMkernel ports, and transport protocols end to end. Unique to VMware, HCI Mesh requires no specialized hardware. Customers can use any vSAN ReadyNode™ to share capacity across clusters. HCI Mesh is scalable. It can support up to 64 hosts across clusters in a mesh. A client cluster can mount up to five remote datastores. HCI Mesh will only be available with vSAN Enterprise and Enterprise Plus Editions.

Fig.: Set Up HCI Mesh

For additional information see the HCI Mesh Tech Note.

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