In our white paper entitled, “Managing Your Data with Software Defined Storage,” we discussed the ideas of separating the control plane from the data plane and running services over commodity hardware rather than custom proprietary hardware. We then examined the benefits brought about by the convergence and implementation of these principles such as:
- The greater degree of elasticity and agility that SDS can incorporate into your data infrastructure
- Real cost savings as data centers are less dependent on hardware driven redundancy solutions such as external disk arrays
- The ability to treat storage as an expanded pool rather than a bunch of isolated storage silos
- Escaping the predicament of vendor lock-in and dependency on specialized data hardware employees
- Allowing the opportunity to transform unstructured data into connected data which increases value for the organization
So how does an organization go about implementing a SDS solution within their enterprise? The good news is that IT departments don’t have to transform the data center in its entirety overnight. The conversion process can occur in a well thought out gradual manner over time. Larger organizations are always contemplating a SAN end-of-line upgrade or the purchase of an additional SAN. Other organizations may be considering the purchase of lower cost data storage solutions to manage data that they previously had never considered valuable such as IoT data. There are also SMB’s who still feel left out of the high availability network storage market due to the high cost of hardware based SANs and the costs of retaining specialized IT talent to manage them.
In all these cases there are simple alternatives out there such as the Virtual Storage Appliance (VSA), which we covered at length in the article, “Get to Know VSA: An Overview of the Virtual Server Appliance” Another solution is the VSAN, or Virtual Storage Area Network, which is more expansive in its design and capabilities than the VSA. A VSAN is designed to offer network storage in similar fashion as a traditional external disk array but there are key differences:
- Like a VSA, a VSAN utilizes direct attached storage thus eliminating the need for a iSCSI or FCP based isolated networks so that zoning switches are a thing of the past
- Traditional storage volumes such as LUNS or NFS shares are not required
- There is no need for a dedicated storage admin as the VSAN simply integrates into the Hyper-visor, making the virtualization admin the storage manager and caretaker
A FOCUS ON VMWARE VSAN 6
Due to the infancy of the VSAN industry, there are currently fewer available solutions than those of the more traditional hardware driven SAN. For this reason, we will focus on VSAN 6 for the remainder of this article as it is the most prevalent VSAN solution available on the market today. VSAN 6.1 is completely hardware agnostic and is designed to abstract logical storage pools from multiple varied, and perhaps dissimilar, storage resources and manage it all through application-centric policy-based automation.
Like the VSA, the VSAN is a software bundle that resides on a virtual machine which is why the foray into virtualized storage makes so much sense for a company such as VMware. VSAN 6.1 integrates directly with vSphere, allowing a vSphere admin to manage both virtualized computers and storage within one pane of glass.1 Like any SDS solution, the VSAN will operate on any x86 server and doesn’t require any complex RAID configuration. LUNs are a thing of the past as it utilizes a concept VMware refers to as vVols. Although it is designed to operate with DAS, it does utilize a transport mechanism called Protocol Endpoints which enables communication between ESXi hosts and storage array systems. Protocol Endpoints are compatible with all SAN and NAS protocols including iSCSI, NFS, FC and FCoE. VSAN doesn’t require any sort of RAID.
If you want to take advantage of SDS through the implementation of a VSAN, you first must consider your desired architecture.
- Hybrid Architecture—a hardware storage configuration consisting of both flash storage disks such as SSD and traditional magnetic disks. In this scenario, you would designate the flash disks for read caching and write buffering before saving it to the magnetic devices, thus increasing performance.
- Flash Architecture—although a flash disk can still be designated as a caching disk, all data storage exclusively resides on flash storage. This provides the optimum level of performance at an astounding obtainable rate of 100,000 IOPS per host.
VSAN 6 requires VMware vCenter Server 6.0 and a clustered environment of ESXi 6.0 hosts. It has a storage capacity of 14 PB and its high degree of scalability supports up to 64 nodes. VSAN is policy driven and requires that every VM placed within the VSAN data store be assigned at least one policy. These assigned policies manage attributes such as disk capacity, performance and availability. Fault tolerance policies can enforce data replication amongst multiple drives or hosts to provide varying degrees of fault tolerance.
A complete storage system needs to offer more service capabilities than just the aspect of storing data. VSAN 6 can vastly increase your storage capacity and maximize infrastructure resources through added services such as deduplication, compression and thin provisioning. Snapshotting can also be implemented which can be used for archival purposes, application testing or rollback environments. All of these features can be easily configured and managed in the vSphere Web Client. This centralization of intelligence and management within the design framework makes it ideal for organizations with branch and remote offices as all data management and implementation processes of those sites can be handled by the central office.
As mentioned earlier, VSAN technology gives SMBs the opportunity to achieve levels of fault tolerance and high availability within the data center that traditionally have been only available with the use of expensive and complex external disk arrays. Even more than that however, is the fact that the notion of disaster recovery has been a pipe dream to so many organizations. VSAN 6 can make this dream come true at a much lower price point through its “Stretch Cluster” feature. Stretched Clustering enables enterprise level availability by offering synchronous replication between data centers that reside at different site locations. Even in the loss of an entire site due to a power outage or natural disaster, data loss can be at or near zero.
Whether it’s working with multiple sites, multiple storage devices or multiple disk technologies, a VSAN provides the granular managerial capabilities to maximize resource efficiencies, performance and redundancy, all without expensive proprietary hardware that requires over provisioning which will allow organizations of all sizes to leverage their greatest asset—information.
Sources:
1. What’s New with VMware Virtual SAN 6.2, Technical White Paper Released by VMware, February 2016
