Going the distance for business continuity

Proof of concept No switch required An alternative to tape Distance assistance

Typical of any company in the financial industry, Euronext.liffe puts a premium on business continuity. After a number of acquisitions, the derivatives trading exchange spent the last year building a high-speed network and setting up dual data centers, one in London, the other in Paris. The company's "dual-site live" strategy means neither data center is a backup to the other. Rather, the two constantly share the load, although the entire business can run from just one, if necessary.

To accomplish dual-site live, the company's IT arm, Euronext.liffe Market Solutions, replicates data between storage-area networks (SAN) located at the two data centers. While such an application might connote a synchronous link using optical technology, Market Solutions is instead using Fibre Channel over IP (FCIP), implemented on its four Cisco MDS 9509 SAN switches. FCIP supports an asynchronous connection over an IP network between Fibre Channel-based storage equipment, which effectively eliminates the distance limitation that has relegated synchronous replication to metropolitan-area applications. That makes FCIP a boon for any company looking to replicate data out of region.

"Any natural disaster or terrorist action is unlikely to lead to losing two data centers in two different countries," says Mark Hemsley, managing director of Euronext.liffe Market Solutions.

FCIP isn't the only technology for asynchronous replication between Fibre Channel-based systems. The Internet Fibre Channel Protocol (IFCP), touted mainly by Nishan Systems (which was recently acquired by storage switch vendor McData), accomplishes the same thing, albeit in a somewhat different fashion.

FCIP and IFCP are implemented in SAN switches that take in a Fibre Channel feed and encapsulate the data in IP. The other part of the equation is software that handles the replication, ensuring data is the same on both sides. All the big storage system vendors have some sort of remote copy software that works at the block or disk level, such as Hitachi Data Systems' TrueCopy and EMC's Symmetrix Remote Data Facility (SRDF) and the recently announced asynchronous version, SRDF/A. Software-only replication from NSI Software, Topio, XOsoft and Veritas Software works at the file-system level, looking for changes as they are written. These offerings work with standard Windows, Unix or Linux servers and require no special switches or transport protocols - just a plain old IP connection.

"The thing that FCIP and IFCP are built for is to have identical storage at both ends, where you mirror data from one site to another," says Marc Farley, president of Building Storage, a storage consulting firm. Products such as NSI Software's Double-Take, on the other hand, replicate data from one server to another, but the two databases might not necessarily be mirror images of one another in terms of data structure, and the data might not be instantaneously available. Yet customers who are using the products say the process works in near real time, certainly fast enough to provide for business continuity, if not instant access to data after an event.