Published: 23 Oct 2013
With SMB 3.0 included in Microsoft Windows Server 2012, using Windows file sharing for virtual environments is much faster, safer and easier. Terri McClure outlines some features.
The ability to reduce both Capex and Opex, and the potential to deliver greater mobility and agility, has kept server virtualization atop IT priority lists: cited by 26% to 33% of respondents, ESG research has ranked server virtualization first on those lists for three of the past four years. The challenge for many organizations, however, has been implementing virtualization with mission-critical, tier-one workloads. IT organizations are concerned that the aggregation of multiple, dissimilar workloads -- often called the "I/O blender effect" -- will create unpredictable, and therefore unreliable, application performance. And while cost reduction has risen in importance, reducing costs seldom outweighs the need for keeping tier-one production applications at peak performance.
The benefits of server virtualization initially come from reducing equipment and energy costs by consolidating multiple application servers as virtual machines (VMs) on a single physical server. But to gain higher-level operational benefits, such as the ability to move workloads for load balancing, high availability and maximum resource utilization, networked storage is a requirement. For example, if you can move a VM from Server A to Server B non-disruptively, you can do maintenance on Server A and still retain data access and production uptime. Virtualization can make an organization more agile and able to respond quickly to both opportunities and threats, but only if networked storage is in play.
There has been increased interest in using network-attached storage (NAS) to support virtualized environments because it can be much easier to manage than SAN storage. At their core, VMs are files -- so they can be managed more easily with a file-based protocol, without the multiple layers of management that block storage needs. A file system exported to a VM travels with that VM among physical servers, maintaining its relationships, and capacity can be added on-the-fly without downtime. It's simple and fast. In contrast, SAN storage requires managing host bus adapters, LUNs and World Wide Names; carving out and assigning LUNs to each VM; establishing and managing switch ports and zones; configuring multi-pathing; cross-mounting LUNs to enable mobility … you get the picture. It's a complex, error-prone and time-consuming process, as well as a more expensive one. It's no wonder IT organizations are looking for an alternative.
What is SMB?
Server Message Block (SMB) is a network file-sharing protocol that allows applications and end users to access files or resources from a remote file server. Microsoft initially introduced SMB as a follow-on to the Common Internet File System (CIFS) with Windows Server 2008 and Vista. The latest version, SMB 3.0, is included with the Windows Server 2012 operating system and works with Windows 8 clients.
SMB 3.0 delivers significant improvements in performance, reliability and security. In particular, when combined with Windows Storage Spaces (a feature of Windows Server 2012 that virtualizes commodity disk into a high-performance, high-availability storage solution), SMB 3.0 can be used with cheap direct-attached storage (DAS), JBOD or RBOD to create a cost-effective alternative to purpose-built NAS appliances (and SAN arrays). As a result, IT organizations can gain enterprise-class features and simpler storage management without having to buy an expensive SAN. In addition, SMB 3.0 now supports applications such as Exchange and SQL Server that were formerly only supported with block storage.
It's worth noting some of the key features of SMB 3.0 and how they deliver better availability, resiliency and performance. All features are simple to manage and need no additional software or administrative expertise.
- SMB Transparent Failover. Enables clients to continue working despite a failure in an SMB file server cluster node. Information is preserved on the server side, with automatic client reconnection to the same shares and files on the surviving cluster nodes. Failover is transparent to the application.
- SMB Scale Out. Using Cluster Shared Volumes v2, SMB Scale Out enables an SMB share to be presented by all nodes in a cluster in an active-active configuration in a single namespace. Access to files is automatically and transparently load balanced across all available cluster nodes. No additional set up or management is required.
- SMB Multichannel. Allows servers to use multiple network connections simultaneously to increase both performance and availability. Data is transmitted across multiple network connections on high-speed network adapters or across multiple network adapters to aggregate performance.
- SMB Direct. Enables the use of network adapters with Remote Direct Memory Access (RDMA), which consumes fewer CPU cycles and lowers latency while increasing performance. Applications can access SMB storage shares at DAS-like speeds.
- SMB Encryption. Allows an administrator to encrypt data with a simple checkbox. SMB Encryption keys are derived from the existing session key, so no keys or certificates are transmitted over the network. No client-side activity is required, and the encryption method is designed to take advantage of built-in acceleration in Core i5 and Core i7 processors.
- Volume Shadow Copy Service for SMB Shares. Allows application-consistent snapshots of data volumes for backup and recovery. The same familiar interface that was previously available only for use with local block storage can now be leveraged for SMB file shares.
- SMB Directory Leasing. Improves application response times in branch offices by limiting the number of accesses required between server and client. The directory structure is cached on the client, and clients are notified when directory information on the server changes to maintain cache coherency.
So, what does this mean in general for the IT industry? With SMB 3.0, IT organizations can use file storage for mission-critical, virtualized applications and get enterprise-class availability, performance and resiliency. If this simple, cost-effective solution provides a viable option to expensive and hard-to-manage SANs, the potential for marketplace disruption is real. While EMC and NetApp partially support SMB 3.0, it will take some time for most of the NAS community to fully support the complete feature set. This leaves a great opportunity for emerging storage vendors to increase market share, particularly if they're certified by Microsoft.
The big question: What will customers think?
While this potential market disruption is intriguing, time and customer reactions will tell the tale. The stuff works -- ESG Lab has completed performance testing and cost analyses that confirm Microsoft's claims. But Microsoft faces a few challenges. SMB 3.0 must be enabled on both the server and client side, but it currently supports only Windows Server 2012 and Windows 8. Most organizations refresh Windows Servers according to a standard three-year lifecycle, and since the OS includes a slew of other benefits (such as improvements to Hyper-V), the upgrade is appealing. But it's common for organizations to have significant lag time before refreshing the client-side operating system, and since Windows 8 offers a substantial change in the user experience, they may be reluctant.
In addition, Microsoft has no reputation in the enterprise storage arena. This isn't insurmountable, but could contribute to a delay in implementation. Enterprise storage administrators are generally not inclined to risk the crown jewels on something new, especially if the vendor has no storage chops.
Businesses have little tolerance for slow application performance, and fear of aggregating workloads has kept many from virtualizing tier-one applications. Prior to Windows Server 2012, the primary option was an expensive, complex SAN infrastructure or NAS (albeit with some challenges when it comes to clustering and failover), or inexpensive storage with no features that limited the server virtualization benefits organizations could realize because of lags in storage functionality. Now, Microsoft is offering a way to get enterprise-class features on low-cost, easy-to-manage file storage. Windows Server 2012 with SMB 3.0 might just disrupt the status quo of the storage market -- and with native tiering and write-back caching in R2, the enterprise feature list expands. All that means storage pros should stay tuned, as things are getting interesting.
About the author:
Terri McClure is a senior storage analyst at Enterprise Strategy Group, Milford, Mass.
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