Understanding the Basics of VMware vSAN

In the realm of virtualization and cloud computing, VMware vSAN stands out as a robust and innovative solution for storage management. As organizations increasingly rely on virtualized environments to power their IT infrastructure, understanding the basics of VMware vSAN becomes essential for IT professionals and businesses alike. In this blog post, we'll explore what VMware vSAN is, how it works, its key benefits and considerations, as well as its implementation and configuration options.

​What is VMware vSAN?

VMware vSAN uses a software-defined approach that creates shared storage for virtual machines. It virtualizes the local physical storage resources of ESXi hosts and turns them into pools of storage that can be divided and assigned to virtual machines and applications according to their quality-of-service requirements. vSAN is implemented directly in the ESXi hypervisor.

How Does VMware vSAN Work?

At its core, VMware vSAN leverages the direct-attached storage (DAS) available in each ESXi host to create a distributed, shared data store across the entire vSphere cluster. This architecture enables vSAN to deliver high-performance, scalable, and resilient storage without the complexity and cost associated with traditional SAN or NAS solutions.
​
You can configure vSAN to work as either a hybrid or all-flash cluster. In hybrid clusters, flash devices are used for the cache layer and magnetic disks are used for the storage capacity layer. In all-flash clusters, flash devices are used for both cache and capacity.

​Implementation and Configuration Options

You can activate vSAN on your existing host clusters and when you create new clusters. vSAN aggregates all local capacity devices into a single datastore shared by all hosts in the vSAN cluster. You can expand the datastore by adding capacity devices or hosts with capacity devices to the cluster. vSAN works best when all ESXi hosts in the cluster share similar or identical configurations across all cluster members, including similar or identical storage configurations. This consistent configuration balances virtual machine storage components across all devices and hosts in the cluster. Hosts without any local devices also can participate and run their virtual machines on the vSAN datastore.

If a host contributes its local storage devices to the vSAN datastore, it must provide at least one device for flash cache and at least one device for capacity. Capacity devices are also called data disks.

The devices on the contributing host form one or more disk groups. Each disk group contains one flash cache device, and one or multiple capacity devices for persistent storage. Each host can be configured to use multiple disk groups.
​
For best practices, capacity considerations, and general recommendations about designing and sizing a vSAN cluster, see the VMware vSAN Design and Sizing Guide.

​Considerations for Deploying VMware vSAN:

1. Hardware Compatibility: Ensure that the hardware components (e.g., servers, disks, network adapters) in your vSphere cluster are certified and compatible with VMware vSAN.
2. Network Requirements: VMware vSAN relies on high-speed networking for efficient data replication and communication between hosts. Consider deploying high-bandwidth network infrastructure to maximize vSAN performance.
3. Data Services and Licensing: Explore the various data services and licensing options available for VMware vSAN, including features like deduplication, compression, and encryption, to meet your specific requirements.
4. Capacity Planning: Properly size your vSAN cluster based on your current storage requirements and anticipated growth, considering factors such as usable capacity, performance goals, and redundancy levels.
5. Training and Expertise: Invest in training and expertise to effectively design, deploy, and manage VMware vSAN in your environment, ensuring optimal performance, reliability, and data protection.

​Key Differences Between vSAN and Traditional Storage

Although vSAN shares many characteristics with traditional storage arrays, the overall behavior and function of vSAN is different. For example, vSAN can manage and work only with ESXi hosts, and a single vSAN instance can support only one cluster.

vSAN and traditional storage also differ in the following key ways:

• vSAN does not require external networked storage for storing virtual machine files remotely, such as on a Fibre Channel (FC) or Storage Area Network (SAN).
• Using traditional storage, the storage administrator pre-allocates storage space on different storage systems. vSAN automatically turns the local physical storage resources of the ESXi hosts into a single pool of storage. These pools can be divided and assigned to virtual machines and applications according to their quality-of-service requirements.
• vSAN does not behave like traditional storage volumes based on LUNs or NFS shares. The iSCSI target service uses LUNs to enable an initiator on a remote host to transport block-level data to a storage device in the vSAN cluster.
• Some standard storage protocols, such as FCP, do not apply to vSAN.
• vSAN is highly integrated with vSphere. You do not need dedicated plug-ins or a storage console for vSAN, compared to traditional storage. You can deploy, manage, and monitor vSAN by using the vSphere Client.
• A dedicated storage administrator does not need to manage vSAN. Instead, a vSphere administrator can manage a vSAN environment.
• With vSAN, VM storage policies are automatically assigned when you deploy new VMs. The storage policies can be changed dynamically as needed.

​Key Benefits of VMware vSAN:

1. Simplicity: VMware vSAN simplifies storage management by seamlessly integrating with VMware vSphere, allowing administrators to manage compute and storage resources from a single interface.
   
2. Scalability: With its distributed architecture, VMware vSAN can easily scale storage capacity and performance by adding additional hosts to the cluster or expanding existing hosts with more disks.
   
3. Performance: By leveraging flash-based storage and intelligent caching algorithms, vSAN delivers high-performance storage with low latency, ideal for demanding enterprise workloads.
   
4. Resilience: VMware vSAN provides built-in data protection features such as RAID-like mirroring and erasure coding, ensuring data integrity and availability in the event of hardware failures.
   
5. Cost-Effectiveness: By utilizing commodity hardware and eliminating the need for expensive storage arrays, VMware vSAN offers a cost-effective storage solution for virtualized environments.
   

​VMware vSAN offers a powerful and flexible storage solution for virtualized environments, enabling organizations to achieve high performance, scalability, and resilience while simplifying storage management and reducing costs. By understanding the basics of VMware vSAN and carefully planning its deployment, businesses can unlock the full potential of virtualized infrastructure to support their evolving IT needs.

References:

• VMware vSAN Design Guide