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Dell VxRail Network Planning Guide
Introduction Planning Your Data Center Network for VxRail VxRail Cluster Types
Introduction to cluster types
Cluster with vSAN storage
Dynamic cluster
vSAN stretched cluster
2-node cluster
Satellite nodes
VxRail Feature-Driven Decision Points VxRail Hardware and Switch Selection Decision Points Prepare Data Center for VxRail Implementation Planning the VxRail Cluster Implementation Planning vSAN Witness Networking Planning VxRail Satellite Nodes Networking Configure the Network for VxRail Preparing to Build the VxRail Cluster VxRail Network Considerations After Implementation Appendixes

Cluster with vSAN storage

Cluster with vSAN storage

  • Architecture options

    One type of VxRail cluster is one where the VxRail nodes provide all the physical compute and storage resources to support application workload, and the primary storage resource is vSphere vSAN. For this cluster type, the slots in the nodes are filled with disk drives that meet the performance and capacity requirements for the application workload and are then formed into a local vSAN datastore during the cluster initialization process.

    This cluster type is designed to handle most customer application workloads and covers the most common use cases.

    • With a local vSAN datastore, operational flexibility can be realized to address scalability and high availability requirements.
    • This cluster type is simple to deploy and operate. The initialization process performs all the work to pool all the node resources for ease of consumption
    • This cluster type is not dependent on external resources for storage, so all resources can be administered under a single point of management.
    • Additional compute and storage resources can be expanded easily to the cluster through automated node and disk drive addition.
    • External storage resources can be configured on the cluster as secondary storage capacity.

     However, this cluster type may not be a good fit for certain use cases:

    • This cluster type may be cost-prohibitive for smaller business requirements. Light workloads, such as those in a remote office, may be a better fit for a two-node cluster or a satellite node.
    • This cluster type is located in a single site. It offers support for continuous operations from a failure of components within the cluster but does not offer zero-downtime protection from a failure of a single data center or site. A stretched VxRail cluster is a better solution for very high availability requirements.

    Expansion of a cluster through node addition can potentially lead to stranded assets, where excess compute and storage resources cannot be shared outside of the cluster. For workloads that require a more precise balance of compute and storage resources, a dynamic cluster may be a better fit.

    VxRail supports two different vSAN architectures. The first architecture is known as the “Original vSAN Architecture” and the second architecture is referred to as the “Express vSAN Architecture.”

    The Original vSAN Architecture is a two-tier model built on the foundation of disk groups. A disk group consists of a single cache drive partnered with one or more capacity drives. A collection of disk groups is used to form a vSAN datastore.

    DiagramDescription automatically generated

    Figure 19.    Local vSAN OSA datastore deployed on a VxRail cluster

    The cluster initialization process performs an inventory of the disk drives on the nodes. It uses that discovery process to identify the number of disk groups on each node to be used as the foundation for the vSAN datastore. The high-endurance SSD drives discovered on each node serve as a cache for virtual machine I-O operations in each disk group, while the high-capacity drives discovered are the primary permanent storage resource for the virtual machines for each disk group. The vSAN build process partners the discovered cache drives with one or more capacity drives to form disk groups, with the resulting vSAN datastore consisting of this collection of disk groups.

    VxRail clusters with vSAN datastores based on the Original vSAN Architecture support solid-state and NVMe drives for both cache and capacity, and solid-state and hard drives for capacity only. This architecture supports network speeds of 10 GbE, 25 GbE, and 100 GbE.

    Express vSAN architecture

    The Express vSAN Architecture is a single-tier model that takes advantage of the adoption of high-performant NVMe drives and the continuous increase in CPU cores to support a datastore based on a single pool of storage instead of disk groups. With this architecture, every drive can serve both cache and capacity requirements.

    Graphical user interface, applicationDescription automatically generated

    Figure 20.    Local vSAN ESA datastore deployed on a VxRail cluster

    During the inventory process, VxRail queries the drive slots and verifies whether a datastore can be built with the Express vSAN Architecture. The datastore will only be built with this architecture if all the drive slots contain compatible NVMe drives.

    If this vSAN architecture option is selected, the network configured to support the datastore must be running at either 25 GbE or 100 GbE.