Definition

virtual storage area network (VSAN)

Contributor(s): John Edwards

A virtual storage area network (VSAN) is a logical partition in a physical storage area network (SAN). VSANs enable traffic to be isolated within specific portions of a storage area network, so if a problem occurs in one logical partition, it can be handled with a minimum of disruption to the rest of the network.

The use of multiple, isolated VSANs can also make a storage system easier to configure and scale out. Subscribers can be added or relocated without needing to change the physical layout.

How VSAN works

A virtual SAN appliance enables unused storage capacity on virtual servers to be pooled and accessed by virtual servers as needed. A virtual SAN appliance is most often downloaded as a software program that runs on a virtual machine, but some storage hardware vendors are beginning to incorporate virtual SAN appliances into their firmware. Depending on the vendor, a virtual SAN appliance might also be called a software-defined storage (SDS) appliance or, simply, a virtual storage appliance.

VSAN vendors and features

The acronym for virtual SAN is spelled differently by different vendors. When spelled with all capital letters, the acronym is usually associated with Cisco Systems and is talked about in conjunction with zoning, which splits a physical SAN into multiple, isolated subnetworks. When spelled with a lower-case v, the acronym is usually associated with VMware and Hyper-V features that allow available hard disk drive storage to be pooled from across clustered hosts.

SAN architecture
A physical storage area network consists of a fabric layer, host layer, SAN switches and a storage layer.

Benefits of virtual storage area networks

  • Nondisruptive data migration. A VSAN enables adopters to migrate data between drives easily and without any downtime.
  • Better information lifecycle management. Virtualization administrators can relocate frequently accessed data to high-performance storage, pushing rarely accessed data regions onto less expensive storage resources.
  • Improved manageability. Although it's relatively easy to manage identical drives, the task can become much more difficult if storage resources involve several vendors or even several models from the same vendor. A VSAN isn't only easy to set up, but straightforward to manage and provision.
  • Overall simplicity. Compared to the available alternatives, a VSAN is easy to provision and manage. This is because the VSAN is embedded directly within the hypervisor, enabling installation and configuration to be handled rapidly and
  • Reduced total cost of ownership. A VSAN can be deployed on inexpensive x86 servers, eliminating the need for large upfront investments.

Virtual storage area network use cases

  • Server virtualization
  • Cloud automation
  • Demilitarized zones and any test environments
  • Virtual desktop infrastructure (VDI) environments
  • Support edge network sites
  • Convert localized storage into virtual storage

This was last updated in September 2020

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