Telescope 2007

Storage: Getting the most from your SAN

Three-tier architectures with a Web-based front-end, an application server and a database server are commonplace. With an increase in the number of users, more data being stored at the back-end, and a consequent rise in the number of requests that a database server has to address, it is harder than ever to figure out where a bottleneck lies in this tangled mess. But solutions are available in the market that help CIOs optimise application performance. Vendors also suggest certain best practices which can help squash the speed bumps in an enterprise data centre. By Rishiraj Verma and Aishwarya Ramani

A company’s growth is almost always the reason for bottle-necks. Along with organisational growth, the data that is accessed daily by its employees also grows. This translates into more users concurrently trying to access data. One way out is to adding devices to the storage sub-system. However, in a traditional file server environment, adding storage devices may increase an administrator’s burdens and may have an adverse impact on performance and device availability.

Says Manish Bapat, National Manager, NAS and CAS, EMC India and Saarc, “As requirements grew, companies bought more devices.” Data in such cases tends to be accessed from each device separately. The picture changed when the concept of networked storage was introduced, i.e. SAN and NAS. This wasn’t however a final solution to these problems. Data growth did not stop and the need for innovation was felt again.

Ketan Parekh

It is this constantly growing data that may be a cause of further concern. According to Ketan Parekh, CTO, Sharekhan, “One of the critical problems while dealing with networked storage is accurately estimating the growth or throughput of data.” He is of the opinion that a correct estimate here can help in getting the right number and size of the discs that need to be used as part of the SAN.

Neeraj Matiyani, Business Manager, StorageWorks Division, HP India, concurs with Parekh’s view. “Improper planning of the network is a contributing factor to bottle-necks.” Most organisations face this problem because growth may exceed expectations. The first step is to understand how much data may be generated and accessed in the near term, and there is no room for miscalculation during this step.

Soumitra Agarwal

Improper classification of data in the earlier stages may be the cause of grief down the line. Says Soumitra Agarwal, Marketing Director, NetApp India, “Unstructured data accounts for about 75 percent of an organisation’s storage capacity.” He insists therefore that issues of classifying, indexing and moving unstructured data to lower-cost tiers must be addressed well in time.

There might also be a sudden increase in the volume of data being accessed over the network. An increase in the number of users, or again, the growth of the organisation, could be the probable causes of this condition. Says Shailesh Agarwal, Country Manager, Storage, IBM India, “If the data is old and is no longer being used, then archiving it to tapes would be the most viable option. However, in the case of critical data, transferring it to lower-cost SATA discs with the use of technologies such as storage virtualisation would be ideal.”

A potential answer

Once the CIO has identified the storage needs, he needs to look at ways of ensuring that the infrastructure is used optimally, without the need for further expenses and increasing efficiency.

Virtualisation, in one form or the other, has always been considered key to reducing IT-related costs and increasing efficiency. In the case of SANs too, virtualisation can help cut down on an administrator’s list of problems. It can also help drastically reduce the complexity involved in creating, editing and deleting files and applications over a network.

With regard to SAN optimisation, Global Namespace (GNS) seems to be something of an answer to a CIO’s troubles. GNS is a logical layer that is inserted between clients and the file systems so that users can access data independent of where a physical file is located.

GNS uses a set of paths and file names (in the form of URLs) that help access specific data. Clients can use the same path for the data, regardless of its geographical location. However, the use of the same path to access data does not mean that the same caches are used to route all requests. As Soumitra Agarwal explains, “A GNS is separated from the actual components—clients, caches and servers that it is built from. It is a one-to-one mapping between a piece of data and the path to it.”

CIOs seem to be welcoming this idea. Parekh feels that GNS is a good concept because “it shields the end-user from the changes taking place in the storage set-up where data resides.” In effect, GNS does much the same thing for storage that DNS does for networking. Clients are able to access data without knowing where it is in the same manner that users access a Web site without knowing its IP address. Apart from helping users, this also helps administrators add, change, move, and reconfigure physical file storage without affecting how users view and access the same.

Vivekanand Venugopal

Vivekanand Venugopal, Director, Software Solutions, APAC, Hitachi Data Systems, is upbeat about it: “It (GNS) is an optimisation technique and will prove to be the future of file management.”

On the other hand, Sumit Mukhija, Business Development Manager, Cisco Systems India & Saarc, takes the concept with a pinch of salt. “It’s a great concept, but it’s still a concept.” According to him, there is not much happening in the market as far as GNS offerings are concerned.

GNS aims to change the way files are managed over a network. Its other goals are to raise data utilisation, cut down on over-provisioning, and resolve bottlenecks without necessarily having to add discs and arrays to a SAN. GNS helps administrators support heterogeneous storage environments. The concept also aims at optimising networked storage across different vendor platforms and storage tiers.