What Is Virtual SAN?
VSAN is a new storage solution from VMware, released as a beta in 2013 and made generally available to the public in March 2014. VSAN is fully integrated with vSphere. It is an object-based storage system and a platform for VM storage policies that aims to simplify VM storage placement decisions for vSphere administrators. It fully supports and is integrated with core vSphere features such as vSphere High Availability (HA), vSphere Distributed Resource Scheduler (DRS), and vMotion, as illustrated in Figure 1-2.
Figure 1-2 Simple overview of a VSAN cluster
VSAN’s goal is to provide both resiliency and scale-out storage functionality. It can also be thought of in the context of QoS in so far as VM storage policies can be created that define the level of performance and availability required on a per-VM, or even virtual disk, basis.
VSAN is a software-based distributed storage solution that is built directly in the hyper-visor. Although not a virtual appliance like many of the other solutions out there, a VSAN can best be thought of as a kernel-based solution that is included with the hypervisor. Technically, however, this is not completely accurate because components critical for performance and responsiveness such as the data path and clustering are in the kernel, while other components that collectively can be considered part of the “control plane” are implemented as native user-space agents. Nevertheless, with VSAN there is no need to install anything other than the software you are already familiar with: VMware vSphere.
VSAN is about simplicity, and when we say simplicity, we do mean simplicity. Want to try out VSAN? It is truly as simple as creating a VMkernel network interface card (NIC) for VSAN traffic and enabling it on a cluster level, as shown in Figure 1-3. Of course, there are certain recommendations and requirements to optimize your experience, as described in further detail in Chapter 2, “VSAN Prerequisites and Requirements for Deployment.”
Figure 1-3 Two-click enablement
Now that you know it is easy to use and simple to configure, what are the benefits of a solution like VSAN? What are the key selling points?
- Software defined: Use industry standard hardware
- Flexible: Scale as needed and when needed, both scale up and scale out
- Simple: Ridiculously easy to manage and operate
- Automated: Per-VM and disk policy-based management
- Converged: Enables you to create dense/building-block-style solutions
That sounds compelling, doesn’t it? Of course, there is a time and place for everything; Virtual SAN 1.0 has specific use cases. For version 1.0, these use cases are as follows:
- Virtual desktops: Scale-out model using predictive and repeatable infrastructure blocks lowers costs and simplifies operations
- Test and dev: Avoids acquisition of expensive storage (lowers total cost of ownership [TCO]), fast time to provision
- Management or DMZ infrastructure: Fully isolated resulting in increased security and no dependencies on the resources it is potentially managing.
- Disaster recovery target: Inexpensive disaster recovery solution, enabled through a feature like vSphere Replication that allows you to replicate to any storage platform
Now that you know what VSAN is, it’s time to see what it looks like from an administrator’s point of view.