Stated on many SAN (storage area network) vendor brochures are the benefits of consolidating your enterprise"s existing DAS (direct attached storage) and NAS (network attached storage) into a single SAN. For many companies, it is still an ongoing battle to try out storage consolidation on SAN. A few, however, have gone on to implement SANs? and are now facing the problem of consolidating their SAN islands.

"Companies are looking at SAN consolidation to further improve their storage utilization and reduce the numbers of their SAN implementations," said Wendy Wang, business manager, Network Storage Solutions, Customer Solutions Group, HP Singapore. "SAN consolidation has an even greater impact on the overall business than direct ROI. Companies are using the increased availability, connectivity, and scalability features of SANs to create and improve their competitive advantage."

But, if implementing a SAN is supposed to consolidate storage, why have the silos of DAS and NAS turned into silos of SANs?

There are a couple of reasons why this has happened.

One of them, according to Lim Beng Lay, Product Marketing and Management Asia South, Hitachi Data Systems Corp. (HDS), is that there had been a lack of fine granularity in resource control.

"Looking back four to five years ago, the aim was to consolidate silos of data in various DAS into a SAN," observed Lim.

"However, what had happened was that the "consolidation" had resulted in the proliferation of a whole bunch of SANs in a single enterprise."

"Previously, when companies consolidated DAS, they managed to drive down cost through software consolidation and staff consolidation," said Lim. "However, what they found out was that, sometimes, the SAN has no fine control over the resources that are allocated to the various applications."

For example, within a SAN with mission-critical server A and test server B, the test server may actually eat up more resources such as I/O requests and cache than the mission-critical server. "This creates the need for companies to have different SANs for different levels of needs, based on mission-criticality or departmental divide," explained Lim. "This led to multiple tiers of SAN which led back to square one ? having multiple silos of storage."

Now, said Lim, the situation is different and there are ways to consolidate the various SANs into a single virtual SAN. For example, said Lim, Hitachi has the capability to allocate the right resources to the right applications. And this can be done not just on a Hitachi array but on non-Hitachi storage as well, such as the Sun Microsystems storage systems.

Another reason is that for many companies, it might make sense initially for businesses to deploy smaller autonomous SANs, said Ajit Nair, technology solutions director, EMC South Asia. However, doing so can limit their overall IT and business benefits, cautioned Nair.

The downside of not doing consolidating is that if the company uses multiple vendors" products, it will need to use multiple software to manage the products, said Lim of Hitachi Data Systems. This directly impacts the company"s operational costs. By consolidating, it reduces complexity and training efforts. If training can be reduced, that is cost saving already.

"For instance, each SAN requires its own management and maintenance, requiring IT staff to perform separate iterations of the same tasks ? an inefficient use of staff resources that increases overall IT costs," explained Nair. "In addition, deploying multiple SANs isolates resources, thereby reducing the number of resources that users can access and share across the enterprise. As a result, many organizations have yet to realize the full range of benefits that their SANs are actually capable of providing."

The virtualisation allows consolidation to be done without different application impacting one another. "And this consolidation can be done with an hour or two by remapping the volumes," said Lim of HDS. And it is not just savings through better utilization, for applications with lower requirements, they can actually be managed at a cheaper cost by moving them onto another cheaper box.

"Many organizations with multiple SAN islands are discovering that they could benefit from more efficient management and better resource utilization," said Nair. "To simplify their IT environments, many of these organizations are beginning to consolidate multiple SAN islands into single, large SAN infrastructures."

According to Nair, consolidating SAN islands can generate a wide variety of operational efficiencies. This can range from IT specific efficiencies such as provisioning server and storage capacity more quickly, utilizing existing resources more efficiently; and centralizing fabric management to reduce complexity and lower demand for highly specialized staffing. Consolidating SAN islands can also help reducing capital and operating expenses, as well as the total cost of storage and synchronizing business initiatives, such as service level agreements, throughout an enterprise IT environment. There is no downside to implementing SAN islands consolidation, he said.