Archives ||  About Us ||  Advertise ||  Feedback ||  Subscribe-
Issue of May 2003 
[an error occurred while processing this directive]
 Home > Case Study
 Print Friendly Page ||  Email this story
Case Study: Citibank's SAN Implementation
A SAN for that competitive advantage

Citibank's DAS infrastructure couldn't keep pace with its growing customer base. It wanted a platform that would let it reduce cycle time for loan processing and beat the competition in terms of online response times. A SAN was the logical solution for this. by Prashant L. Rao

A century after it commenced operations in the country, Citigroup provides banking and investment services to two million customers—both consumer and corporate. The company is also one of India's top credit card issuers with close to three million card members.

The Technology Operations team at Citibank India manages the company's financial applications and related transactions. Its mission extends to managing the bank's website ( that lets its Indian customers apply for loans, open accounts, view statements, and pay their bills.

In a nutshell

The company
Citibank India provides banking and investment services to two million customers—both consumer and corporate. The company is also one of India's top credit card issuers with close to three million card members.

The need
The company needed to build a storage infrastructure that would cost-effectively manage its growing storage requirements, improve network performance, reduce management costs and improve system availability. The existing DAS set-up couldn't scale adequately and was becoming increasingly difficult to manage.

The solution
A Storage Area Network (SAN) based on 2 Gbps Brocade SilkWorm 3800 fabric switches and 1 Gbps SilkWorm 2800 fabric switches, connecting a network of Sun and HP servers with an EMC Symmetrix 8530 disk array and a StorageTek L7000 tape library.

The benefits
Competitive advantage as a result of 20 to 30 percent faster back-end processing. End-to-end network fault tolerance has increased system availability. Hardware consolidation and centralised SAN management have led to improved resource utilization. Cost-effective scalability helps handle Citibank's rapid business growth. Faster applications lead to faster business growth.

The need for a SAN

Citibank India pioneered the electronic banking industry in the country by introducing e-banking and its website offers a bouquet of services ranging from online statements of bank accounts or credit card history to loan applications and online bill payment. With the goal of leading the industry in response time on its Internet banking site, and for credit card transaction processing at merchant locations, Citibank India knew that it would need to transform its IT infrastructure. In particular, the company wanted to implement larger servers, additional storage capacity and a more reliable network to streamline application processing.

Over time, the technology team realised that its traditional Direct Attached Storage (DAS) environment was not flexible enough to keep pace with the company's anticipated business growth. In the existing DAS environment, each host server was directly attached to a storage device and data on that device could only be accessed via the LAN through the operating system of the attached server. As the bank's demand for data storage grew, it was forced to add more server-storage pairs, each with its own operating system dependent backup and recovery software.

Somnath Sarkar, Vice President of Technology Operations at Citibank India (Consumer Bank) says, "In the next year we plan to open at least 100 more bank branches and expect an almost 200 to 300 percent increase in transaction volume. We are growing very fast, so network scalability is critical."

Citibank understands that an IT project is only as good as the technology that powers it. Sarkar collaborated with Citibank's local IT partner, EMC India, and designed the SAN. "When it comes to SAN infrastructure we looked for a vendor who could provide quality products, advance features, interoperability with any server or storage vendor; better ROI and ease of implementation and management," adds Sarkar.


To meet its new business objectives, Citibank India decided to migrate from a DAS environment to a high-performance, scalable SAN. The rollout began in April/May of 2002 and was finished by August that year. A pilot was done to test the functionality and capacity. The testing was satisfactory and the stress test revealed the capacity of the switches. EMC conducted the training with consultant help from Brocade.

Today, the SAN environment features a heterogeneous network of Sun and HP servers. The server pool includes a Sun Fire 15000 server, two HP-UX servers, and several Tru64 Unix servers. Citibank India's storage set-up is made up of an EMC Symmetrix 8530 disk array and a StorageTek L7000 tape library—the company has a mammoth storage capacity of 14 terabytes. The core of the SAN consists of the SAN fabric—a redundant dual-fabric configuration of Brocade SilkWorm Fibre Channel switches connects all the servers and storage devices. The switches include two 2 Gbps 16-port SilkWorm 3800 switches and two 1 Gbps 16-port SilkWorm 2800 switches.


By implementing a SAN, Citibank India has derived some immediate advantages, not the least of which is a 10 to 20 percent improvement in performance while processing online customer transactions. The bank has also seen a 20 to 30 percent improvement in handling back-end processing jobs. These performance gains are directly impacting the company's market competitiveness and its bottom line for the better.

Sarkar says, "Reducing cycle time for loan processing and beating the competition in terms of online response times will definitely help us grow our business volume. We have also seen performance gains for credit card transactions at merchant locations. If the merchants are able to process our credit cards faster on Citibank terminals, which saves us from paying service fees to other banks. In fact, we should even be able to process other banks' credit transactions, so we can charge them service fees to increase our revenues."

Through the SAN, Citibank India has succeeded in consolidating its server and storage devices thereby boosting resource utilization. That said, the bank hasn't wasted its old infrastructure. Its existing DAS devices displaced by the larger servers and storage systems have already been re-deployed to a development environment. Not only has the SAN implementation led to improvements in scalability, performance, and resource utilisation, it has also addressed the objective of increasing system availability, which is a must for providing a foundation for end-to-end fault-tolerance throughout the network.

Indirect benefits include skipping a database generation. Sarkar says, "The SAN has definitely increased our ability to keep applications running in the event of a failure. We also are using Oracle 9i Real Applications Cluster (RAC), which makes data movement from one domain to another transparent. Initially, our plan was to migrate from Oracle 7 to Oracle 8, but the SAN enabled us to move to Oracle 9i RAC and all its advanced availability features."

"We have seen excellent stability, even though it's a very new environment," Sarkar adds. "The SAN has been a very cost-effective way to help our business continue to scale up."

Backup windows, which are troublesome, have been dramatically shortened. "Before the SAN implementation, we used to backup a 10-terabyte database every other day. With the SAN, we have seen almost a 100 percent improvement in our backup windows, so we can now back up most of our databases on a daily basis," concludes Sarkar.

Future plans

Future additions to the SAN will depend on Citibank India's capacity planning requirements needed to support its business growth that is expected to be in the range of 30 to 40 percent in 2003. The company plans to extend the SAN for disaster recovery.

Prashant L. Rao. can be reached at

- <Back to Top>-  

© Copyright 2001: Indian Express Newspapers (Bombay) Limited (Mumbai, India). All rights reserved throughout the world.
This entire site is compiled in Mumbai by the Business Publications Division (BPD) of the Indian Express Newspapers (Bombay) Limited. Site managed by BPD.