Dynamic clusters differentiate themselves from other VxRail cluster types with the resource selected for primary storage. With other cluster types, there is a dependency on the local vSAN datastore as the primary storage resource. With a dynamic cluster, the nodes used to build the cluster do not have local disk drives. Therefore, an external storage resource is required to support workload and applications.
A dynamic cluster may be preferable to other cluster types in these situations:
If a dynamic cluster is the best fit for your business and operational requirements, be aware of the following:
One of the external storage resources supported with dynamic clusters is Fibre Channel storage. With this option, a compatible Fibre Channel storage array can be configured to supply a single VMFS datastore or multiple datastores to a VxRail dynamic cluster.
Figure 16. Dynamic cluster using FC-connected VMFS for primary storage
This option has the following prerequisites:
Another option to use for primary storage with dynamic clusters is an existing vSphere or VxRail cluster with a local vSAN datastore in your data center. The virtual machines running on the dynamic cluster will use the free storage resource on the vSAN datastore, and the compute resources on the local nodes.
Figure 17. Dynamic cluster using a remote vSAN datastore for primary storage
If you choose to pursue this option, ensure that the following guidelines are understood:
PowerFlex is a Dell storage product that is supported with VxRail dynamic cluster. PowerFlex systems provide IP-based storage to VxRail dynamic clusters that can be configured as primary storage for virtual machine workload.
Figure 18. VxRail dynamic cluster storage provided by PowerFlex virtual volume
The PowerFlex system configures pools of storage through a virtualization process and manages the allocation of virtual volumes to connected clients. Virtual volumes can be configured to meet certain capacity, performance, and scalability characteristics to align with the workload requirements planned for the VxRail dynamic cluster.
The PowerFlex architecture combines both the compute and storage in a fabric connected network architecture, with Dell PowerEdge servers serving as the hardware foundation for block storage capacity.
Figure 19. PowerFlex system interconnected with VxRail dynamic cluster
If you plan to leverage virtual volumes provided by a PowerFlex system to serve as the primary storage for your VxRail dynamic cluster, ensure that best practices are followed to ensure a successful deployment:
If the data center does not support Fibre Channel storage or shared vSAN resources, or if it does not have a PowerFlex storage array deployed, storage based on either iSCSI or NFS over an IP network can be used as primary storage.
Figure 20. External storage based on iSCSI or NFS supporting VxRail dynamic clusters
With the iSCSI option, block-level storage is presented to the VxRail cluster over an IP network. iSCSI is standard feature in VMware vSphere and is enabled by configuring a software adapter on a NIC on the VxRail nodes. The adapter serves as an iSCSI initiator by targeting external storage arrays to present LUNs back to the initiators. These LUNs are then configured as VMFS datastores to support virtual machine workload.
The NFS option also works over an IP network, except the storage presented back to the VxRail cluster is from a compatible file server, and the storage format is file-based instead of block-based. With this option, the external file system is mounted by the VxRail nodes to enable access over the IP network and configured to serve as a datastore.
As with the other storage options for dynamic clusters, verify that the storage resource in your data center you planned to support VxRail dynamic clusters, consult the VxRail E-Lab Navigator to verify compatibility.