Hyper-Convergence/Server SAN Solutions
In today’s world, the hyper-converged/server SAN solutions come in two flavors:
- Hyper-converged appliances
- Software-only solutions
A hyper-converged solution is an appliance type of solution where a single box provides a platform for VMs. This box typically contains multiple commodity x86 servers on which a hypervisor is installed. Local storage is aggregated into a large shared pool by leveraging a virtual storage appliance or a kernel-based storage stack. Typical examples of hyper-converged appliances that are out there today include Nutanix, Scale Computing, SimpliVity, and Pivot3. Figure 1-1 shows what these appliances usually look like: a 2U form factor with four hosts.
Figure 1-1 Commonly used hardware by hyper-converged storage vendors
You might ask, “If these are generic x86 servers with hypervisors installed and a virtual storage appliance, what are the benefits over a traditional storage system?” The benefits of a hyper-converged platform are as follows:
- Time to market is short, less than 4 hours to install and deploy
- Ease of management and integration
- Able to scale out, both capacity and performance-wise
- Lower total costs of acquisition compared to traditional environments
These solutions are sold as a single stock keeping unit (SKU), and typically a single point of contact for support is provided. This can make support discussions much easier. However, a hurdle for many companies is the fact that these solutions are tied to hardware and specific configurations. The hardware used by hyper-converged vendors is often not the same as from the preferred hardware supplier you may already have. This can lead to operational challenges when it comes to updating/patching or even cabling and racking. In addition, a trust issue exists. Some people swear by server Vendor X and would never want to touch any other brand, whereas others won’t come close to server Vendor X. This is where the software-based storage solutions come in to play.
Software-only storage solutions come in two flavors. The most common solution today is the virtual storage appliance (VSA). VSA solutions are deployed as a VM on top of a hypervisor installed on physical hardware. VSAs allow you to pool underlying physical resources into a shared storage device. Examples of VSAs include VMware vSphere Storage Appliance, Maxta, HP’s StoreVirtual VSA, and EMC Scale IO. The big advantage of software-only solutions is that you can usually leverage existing hardware as long as it is on the hardware compatibility list (HCL). In the majority of cases, the HCL is similar to what the used hypervisor supports, except for key components like disk controllers and flash devices.
VSAN is also a software-only solution, but VSAN differs significantly from the VSAs listed. VSAN sits in a different layer and is not a VSA-based solution.