What is vSAN
vSAN, or VMware vSAN, is a software-defined storage solution provided by VMware. It is designed to create a shared datastore across a cluster of servers using their local storage resources.
VMware Virtual SAN (vSAN) is an integrated software layer designed to operate seamlessly within the ESXi Hypervisor. Functioning as a distributed system, vSAN aggregates local storage capacity and direct hardware connections from a host cluster, establishing a unified and shared storage pool across all hosts within the vSAN cluster.
Explore a detailed guide on VMware vSAN, its installation, and requirements. Get insights into the hardware and software prerequisites and understand its usage and benefits.
vSAN 8 Requirements and Considerations
vSAN operates as a cluster feature, akin to other cluster functionalities like High Availability (HA) and Distributed Resource Scheduler (DRS), which are configured and activated at the cluster level. This implies that vSAN functions to collectively manage storage resources across all hosts within a given cluster. In essence, it operates as an integrated storage solution that spans the entire cluster infrastructure.
Activating vSAN at the cluster level allows the creation of a shared storage pool, utilizing the local storage devices from each host in the cluster. However, it’s essential to ensure that the cluster and environment meet all necessary prerequisites before enabling the vSAN feature. These prerequisites vary depending on the chosen architecture: Original Storage Architecture (OSA) or Express Storage Architecture (ESA). Moreover, the deployment type (Standard, Two-Node, Stretched) dictates specific requirements, varying in complexity and scale. This blog post will delve into vSAN 8 requirements, emphasizing different deployment types and their respective considerations.
The specified prerequisites apply universally to all three deployment types (Standard, Two-Node, Stretched), irrespective of the chosen configuration. Thus, it is imperative that the environment satisfies these conditions. The subsequent table delineates the requisites for both hybrid and all-flash clusters within the Original Storage Architecture (OSA).
The table provided delineates the prerequisites for an all-flash cluster within the Express Storage Architecture (ESA). It’s important to acknowledge that, within this architecture, exclusively an all-flash cluster option is accessible.
Maintaining a uniform ESXi version across all hosts within the vSAN cluster is crucial for ensuring compatibility and preventing potential complications that may arise from using mixed ESXi versions. This consistency promotes a stable and reliable environment.
- Consistent ESXi Version: Maintaining a uniform ESXi version across all hosts in the vSAN cluster is imperative. This uniformity guarantees compatibility and mitigates the risk of complications that may arise when dealing with mixed ESXi versions within the cluster.
- vCenter Compatibility: The vCenter server overseeing the vSAN cluster has the flexibility to be of a higher version than the ESXi hosts it manages. This arrangement enables the independent upgrading of vCenter, providing the advantage of enhancing its features or applying updates while ensuring the ongoing stability and functionality of the vSAN environment.
After meeting all specified prerequisites and successfully configuring a vSAN cluster, the next crucial step is to assign an appropriate vSAN license to the cluster. There are two primary types of vSAN licenses available for this purpose:
- Subscription Licensing: VMware vSAN is available for licensing based on a per-core metric and is provided in various editions, including Standard, Advanced, Enterprise, and vSAN+.
- Perpetual Licensing: VMware vSAN offers various licensing options tailored to specific deployment scenarios. Licensing can be based on a per-CPU model, a per-concurrent user model in 10 or 100 license packs for Virtual Desktop Infrastructure (VDI), or a per-virtual machine (VM) model in 25-VM license packs for Remote Office/Branch Office (ROBO) implementations. The vSAN Standard, Advanced, and Enterprise editions are available for licensing based on these metrics. However, it’s important to note that the vSAN Enterprise Plus edition is exclusively offered on a per-CPU license basis. These diverse licensing options provide flexibility for organizations to align their vSAN deployment with their specific needs and usage scenarios.
Now, I will explore various factors to consider when selecting the deployment types for your environments.
1- Standard vSAN Cluster
When preparing for a typical vSAN deployment, it is essential to consider various foundational prerequisites in addition to the requirements mentioned earlier.
- vSAN requires a minimum of three ESXi hosts in the cluster
- The network round-trip latency between the hosts should not exceed 1 millisecond.
- It is recommended to have a minimum of 10 Gbps dedicated network connectivity to achieve optimal performance.
2- Two-Node vSAN Cluster
In the context of deploying virtualization solutions in remote and branch offices (ROBO) where resources are constrained, VMware vSAN provides a specialized 2-node configuration. Certain considerations need to be taken into account when planning for such deployments:
- vSAN requires two ESXi hosts in the cluster
- The vSAN Witness Appliance serves the essential function of establishing quorum in a 2-node configuration. This component can be implemented either as a virtual machine or on a dedicated hardware appliance. While the optimal practice involves deploying the vSAN Witness Appliance in a secondary location, it is also a viable option to deploy it on an alternate host within the same site.
- The round-trip latency within the network connecting the hosts must be kept below 1 millisecond.
- The round-trip network latency between the hosts and the witness host must stay below 200 milliseconds.
3- vSAN Stretched Cluster
The vSAN stretched cluster feature enables organizations to attain high availability by extending their infrastructure across geographically dispersed locations. To deploy a Stretched Cluster, certain additional criteria and prerequisites need to be satisfied.
- In a stretched cluster configuration, a vSAN Witness Appliance is essential to establish the required quorum. This appliance, crucial for maintaining data consistency, has the flexibility of deployment either as a virtual machine or on a dedicated hardware appliance. It is imperative to deploy the vSAN Witness Appliance in a distinct third location, ensuring separation from both the primary and secondary sites while maintaining connectivity to both. This strategic placement enhances the resilience and reliability of the stretched cluster architecture.
- Keep the round-trip communication latency between the hosts under 1 millisecond.
- Ensuring that the network round-trip latency between sites does not surpass 5 milliseconds is essential. A network connection with low latency and high bandwidth is critical to uphold synchronous data replication effectively.
- It is essential to maintain a network round-trip latency of less than 200 milliseconds between the primary and secondary sites, as well as with the witness host.
What is difference between vSAN and SAN?
The hypervisor integrates VMware vSAN, a software-defined storage solution that pools local storage from multiple servers. It operates at the VM level in a hyper-converged model. A traditional SAN is a dedicated storage network using centralized storage arrays connected to servers through Fibre Channel or iSCSI. It involves specialized hardware and a separate management interface.
ESXi is a hypervisor for virtualization, managing compute resources. vSAN is a software-defined storage solution, pooling and utilizing local storage from multiple ESXi hosts for VM storage.
vSAN (Virtual SAN) is a software-defined storage solution. It is a software component that aggregates and utilizes local storage resources from multiple physical servers to create a shared storage infrastructure.
vSAN, often in conjunction with VMware’s ESXi hypervisor, operates within a virtualized environment, considering itself a software solution while relying on underlying hardware.
What is vSAN used for?
In virtualized environments, organizations use vSAN to create a shared storage infrastructure, offering high availability, scalability, and policy-based management for virtual machines.
Click on the link to start download the vCenter along with vSAN.