VMware vSAN: A New Era of Software Defined Data Centers
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VMware vSAN: A New Era of Software Defined Data Centers

By CIOReview | Wednesday, August 30, 2017

The era of technology is impacting today's business initiatives and imperatives. And on most occasions every enterprise is involved in one or more IT projects. Due to this rapid digital transformation, IT organizations are forced to revamp their data center infrastructure in a way that eliminates the need for new training and skills.

vSAN, the only vSphere-native software-defined storage platform, assists organizations move towards hyper-converged infrastructure (HCI). And this step reduces IT cost, provides agile future-ready hardware and cloud applications. vSAN comes with flash-optimized secure storage feature that ingrains industry's first HCI encryption at a lower cost than its traditional counterparts. Server attached storage is stitched with vSAN to provide highly resilient shared data-store for any virtualized workload such as business-critical applications, virtual desktops, remote IT, DR, and DevOps infrastructure.

Quality of Service (QoS) in vSAN Environment

vSAN is architected to provide quality of service. This is achieved by limiting the number IOPS that an object may consume. Underutilized machine may or may not require such limits as it might have the sufficient resources to meet workload requirement. While having more than the resource is intriguing, it also is accompanied by cost. Efficiently sized configuration offers the best mix of cost and convenience. The quantification of appropriate resources for a workload changes over time especially when utilization grows or new workloads are added.

There are many scenarios where limiting IOPS of one or more virtual machines might prove advantageous. Noisy neighbor, term used to describe a situation where workload monopolizes available I/O or other resources, has negative impact on workloads on the same platform. For mixed environments - high and low utilization - this can have detrimental effect on virtual machines with low utilizations. Moreover, it will also coerce such machines to change its working pattern and consume massive resources. At large, such a scenario will adversely affect business units, tenants, and customers.

With the quality of service feature embedded in vSAN, such a scenario can be averted. QoS for vSAN is a Storage Policy Based Management (SPMB) rule. As QoS is applied to vSAN via a storage policy, it can be either applied to individual component or the entire virtual machine without interrupting its operation.

What hardware best suits vSAN environment?

Usually vSANs are flexible with any hardware. The modicum hardware requirement for building vSAN is three clustered hosts that run ESXi 5.5 update 1 or higher. In addition, these hosts must have one network interface card (NIC), which runs at a minimum of 1 GB per second. VMware, however, recommends the use of 10 GB NIC for a better all-round performance.

Speaking from storage requirement point of view, each server that accounts for storage will require a SATA or SAS host bus adaptor or alternatively a RAID controller. Furthermore, one hard drive disk (HDD) and one solid state drive (SSD) is a must for each capacity-contributing node.

These requirement, although seems simple, it is to be noted that VMware provides all the information at one place. VMware's hardware compatibility list provides detailed information of all hardware that will work best with vSAN. As a best practice, organizations should avoid using hardware not mentioned in the list. The non-certified hardware might work but its use is not officially supported.


The key element of software defined data center is storage, and VMware's vSAN is tailored specifically to meet this prerequisite. While its relatively new feature has arrested the attention of many administrators and C-suite executive, further innovations awaits vSAN framework.

The next version of VMware vSAN, as announced in VMWorld, will embed SSD capabilities in the capacity layer. This will not only change the perception about significance of flash usage in data center, but will pave the way for a better performing vSAN infrastructure as well.