Storage virtualisation

Server virtualisation places significant new demands on traditional storage, says Terri McClure, senior analyst at Enterprise Strategy Group. “The standard storage architecture was originally designed for monolithic mainframes — not the abstraction and pooling of resources.”

Consequently, having virtualised their servers, many enterprises are now looking at virtualising their storage systems as well, to ensure the cost savings and efficiencies gains are not throttled elsewhere in the infrastructure. One major benefit of storage virtualisation is that it eliminates dependencies between the data and its storage location, and gives enterprises an opportunity to unify storage environments made up of disparate types and brands of storage.

However, the move to storage virtualisation necessitates a new strategy, one that coordinates server, storage and network resources to support virtual machines (VMs) in an efficient way. It also requires the implementation of management tools that can unify and coordinate storage pools across the entire system, and present a single view to infrastructure managers.

The London Clinic has done just this, and is a heavy user of virtualised storage. Storage virtualisation has helped relieve storage pressures caused by the clinic’s burgeoning Electronic Health Records (EHA) and Picture Archiving & Communication Systems.

The software system, BridgeHead’s Healthcare Storage Virtualization (HSV), creates common pools of shareable storage hardware that can be accessed as required, regardless of the application or data type, or its location (e.g. tape, disk, Cloud, or virtual tape library). HSV uses meta-data and full-text indexing, and ‘federated search’ tools to locate patient information across the storage pool. “The suite of products provides a comprehensive platform for clinical and administrative data and storage management,” comments Mike Roberts, IT director at The London Clinic.

Forrester Research principal analyst Richard Fichera concurs that over the past two years there has been a rapid expansion in converged infrastructure technologies that facilitate storage virtualisation. “Forrester expects this pace to continue in 2012,” he says.

Fichera adds that vendors will focus on improving the integration of storage and network virtualisation, while enhancing systems-level virtualisation capabilities with higher-level management software. Three suppliers will lead the charge with a combination of blade servers and virtualisation software, says Fichera: Cisco Systems, HP, and IBM.

One of the big attractions of these server platforms will be ‘converged infrastructure’ features that can present components such as servers, network, storage, and security policies, as abstracted ‘application services’.

However, Fichera warns that infrastructure managers will need to come to terms with the new complexities that converged infrastructure brings. There will also be an inherent lack of standardisation above the basic VM layer, which may lead to vendor lock-in. “This isn’t necessarily bad as long as the tradeoffs for lack of vendor choice are mitigated by tangible benefits from the solution,” he says.

Storage tiering

For many organisations wanting to unify their storage estates, automated storage tiering is a common approach, which uses policies to make most efficient use of existing resources.

“In-house automated tiering can be extremely beneficial,” comments Nathan Pearce, product manager EMEA at IT infrastructure firm F5. “These solutions enable use of local storage pools based on Solid State Drives (SSDs) and Hard Disk Drives (HDDs), but they also include the ability to automatically move older, less frequently accessed data and backup copies to a ‘Cloud storage tier’ from major service providers.”

He adds that, given typical usage patterns for file data, this approach can provide excellent performance for critical data, such as new files and VM images, while seamlessly migrating inactive and archive data to a highly elastic and remote cloud tier.

Pearce said: “Cloud storage promises almost limitless scalability and a pay-as-you-consume format, particularly appealing for lower-tier and archive storage. Clouds are physically remote, enabling organisations to get their data off-site for disaster recovery protection. Being an outsourced service, they can also reduce storage management and the logistics of housing storage infrastructure.”

Storage tiering can be implemented in a number of ways. It could be as simple as using an archiving package, which moves files to an archive tier or library, leaving a stub file behind. However, working with a large number of stub files can cause delays in file retrieval. Working with a completely virtualised file system can be much more efficient, experts argue.

Many storage arrays include optional software that can identify data appropriate for each tier, and move it based on predetermined usage policies.

Access problems

However, one issue with virtual storage infrastructure is that there may be problems accessing data where virtual servers are spread across geographical locations, comments Jeff Aaron, WANop consultant at Silver Peak, a WAN appliance supplier.

He says that the benefits of virtualised storage, such as efficiency and storage costs consolidation, can be lost to access and latency issues. This may drive enterprises to spend money on buying more WAN capacity or upgrading servers.

“The emergence of cloud computing and virtualisation only exacerbate these challenges, resulting in hidden costs and a widening vulnerability gap that can seriously compromise business continuity plans,” Aaron says.

Storage virtualisation looks set to deliver the sorts of benefits that server virtualisation brought to many enterprises, such as hardware consolidation and unification, and data efficiency. However, introducing converged infrastructure into the organisation will require re-architecting the whole IT system, servers, network, storage and all, in order to experience the gains.

Nevertheless, Forrester’s Fichera concludes that for 52% of infrastructure professionals surveyed by Forrester, IT infrastructure and data centre consolidation through virtualisation or server consolidation is a ‘high priority’ for this year, and a ‘critical priority’ for 29%.

“The pace of infrastructure transformation, as part of the process of providing new capabilities, continues. Infrastructure and operations professionals are carrying on with consolidation projects including server as well as network, storage, and entire data centres. This effort continues alongside and as part of continued efforts to virtualise and standardise the data centre environment,” says Fichera.

Copyright © 2012 IDG Communications, Inc.

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