Traditional SAN Technology vs. VMware vSAN

Storage Area Networks

The most comprehensive centralized storage solution, SANs facilitate true storage sharing since data is stored at the block level. SAN is a form of centralized storage that is composed of a network of shared storage devices.

It facilitates data transfer between computer systems (as well as other endpoints) and storage devices, usually a tape drive, library, or disk array. SANs provide an architectural framework that enables IT managers to connect remote storage devices to servers in such a way that the devices seem to be locally attached.

Benefits of SAN Technology

A major advantage of using a SAN is its improved disk utilization. Since storage is centralized, everything can be managed as a single entity. IT managers can call up several pools of resources for storage placed at network levels and assign such storage to any and all server applications. SANs also offer businesses increased security of critical data by enabling disaster recovery via replication.

Although SANs were mostly used by large enterprises, SMBs can also benefit from such storage architecture. Small and growing businesses usually find it cost-effective to use direct attach storage (where storage disks are connected to a single server); however, overall costs quickly mount up with an increase in storage demands and data.

This means that direct-attach storage is no longer advisable for enterprises, especially in the face of mission-critical systems, strict privacy laws, and the explosive growth of digital data. With the exponential growth of digital information flowing through business entities in today’s globalized marketplace, enterprises would do well to consider a centralized storage network that can meet their current and future needs.

Virtualized Storage or vSAN

Simply put, virtualized storage refers to the abstraction of storage. A software layer sits between the server (usually a virtual machine), providing an abstracted version of the underlying physical storage. This allows for the partitioning or combination of the full storage capacity as needed.

vSAN is software-defined storage that enables organizations to pool storage capabilities and automatically provision virtual machine storage. They can dynamically scale performance and storage capacity as needed and render underlying physical storage accessible to virtual machines through a policy-driven control pane. Unlike conventional networks that are resized switch-by-switch, virtualized storage can be resized port-by-port.

vSAN logically partitions physical storage area networks and allows the isolation of traffic within specific portions of the network. If there is an issue with a logical partition, it can be discreetly handled without disrupting the rest of the network.

Some of the benefits of virtualized storage include:

Nondisruptive data migration

Before the development of virtual storage technology, it was difficult for organizations to migrate to another storage platform. Since such migrations entailed application outages, lots of resources and were extremely difficult to coordinate across business units and teams, most organizations kept their storage arrays even when the technology became obsolete and vendors no longer supported them.

With the advent of virtualized storage, storage managers could execute disk array swap-outs without affecting other teams and business units. With vSAN facilitating easier and nondisruptive data migration, organizations can now take advantage of the declining cost of storage to migrate to better architectures.

Information lifecycle management (ILM)

Business databases and applications often have certain regions of data that are frequently accessed. Such data regions require high-performance storage while other rarely accessed regions can be relegated to more cost-effective storage. Since vSAN sits between the storage hardware and the server, it is aware of the organization’s data access patterns.

By analyzing such data access information, virtualization engines can relocate frequently accessed data to high-performance storage and push other rarely accessed data regions to less expensive storage, thus enabling true ILM.

Differences Between SAN and vSAN

Although traditional SAN and vSAN technology share many characteristics, vSAN doesn’t require external networked storage to remotely store virtual machine files. vSAN only work with ESXi hosts, while SAN leverages storage protocols such as FCP and iSCSI.

With a traditional SAN, storage administrators are required to pre-allocate storage on different systems, while vSAN automatically converts local storage resources into a single storage pool.

Lastly, organizations use SANs to interconnect shared pools of storage devices to different servers. vSAN extends this local storage to a shareable storage in each server, enabling other servers to access data over the LAN without a traditional shared storage device.