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:
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 21. 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 22. 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 23. 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.
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, shared vSAN resources or have a PowerFlex storage array deployed, storage over an IP network is supported for VxRail.
Figure 24. IP-based external storage supporting VxRail dynamic clusters
The supported storage resources can be either block-based or file system based. With block-level storage option, the LUN is presented to the VxRail cluster nodes over an IP network. vSphere is then used to configure a VMFS datastore from the LUN.
iSCSI is supported with VxRail, and is a standard feature in VMware vSphere. iSCSI is enabled by configuring a software adapter on a NIC on the VxRail nodes. The adapter then serves as an iSCSI initiator by targeting external storage arrays to present LUNs back to the initiators.
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.
Leveraging NVMe (Non-Volatile Memory Express) is supported with VxRail for connecting to block-based storage. NVMe can support local storage devices over PCIe, and storage devices over an FC network or an IP network. NVMe can serve as an alternative to FC or iSCSI storage for demanding workloads, as it is designed for usage with faster storage devices enabled with nonvolatile memory.
Figure 25. NVMe software stack in vSphere
With all the storage options for dynamic clusters, verify that the storage resource in the data center you plan for VxRail dynamic clusters is supported. See the VxRail E-Lab Navigator to verify compatibility.