Storage area networks are making inroads into the New Zealand IT community, even among medium-sized organisations. They offer the enticing possibility of consolidating disk storage and backup in a single location, improving scalability, flexibility in assigning disk space, and centralised management. But users warn SAN is still a developing technology and not to be taken on without a good deal of planning. Stephen Bell investigates.
Most SAN users, as US-based IBM storage specialist Scott Drummond pointed out (see Computerworld, May 21), are still in the “early adopter” class. The majority of businesses that may benefit from SANs are hanging back, waiting for proven financial benefits or for standards to stabilise.
As Drummond says, SAN involves five components working together: servers; the SAN fabric (switches); storage media; software; and services.
There are still no unified standards, particularly in the switching component, and to approach it from a simplistic cost-cutting perspective of plugging together components from the cheapest or most readily available source is likely to lead to problems and disappointment.
SAN is firmly associated with fibre channel technology in the minds of many suppliers and prospective users, but there are other technologies emerging.
“Using gigabit ethernet and SCSI over TCP offers significant economic benefits,” says Alex Winokur, an engineering executive at SANgate Systems, a data storage management company in Massachusetts. “The vast number of ethernet equipment manufacturers, coupled with the technology’s maturity, means ethernet equipment will always be more readily available than fibre channel, and work to more clearly established standards. Management tools are more readily available — something seen as a gap in fibre channel SANs.
Issues such as security and quality of service have already been dealt with — and continue to be improved — in TCP/IP networks, while fibre channel vendors are just beginning to scratch the surface, Winokur says.
Fibre channel vendors argue that fibre channel is optimised for storage applications and provides much higher performance than the combination of TCP/IP and ethernet. TCP-ethernet supporters point to the development of TCP accelerators and TCP/IP stacks embedded in silicon.
Planning is needed in advance as to the amount of storage and likely growth rates (and other aspects), and the task is far from finished when the system is plugged together and working.
Management is key. The user not only needs to manage storage over the SAN, which means managing backup and disaster recovery (a facet difficult to provide in New Zealand) but also data movement and data sharing.
Drummond, however, says it is the software that should be chosen first — network management software and backup management — because that is the hardest thing to change once a complete interlocking system is in place.
There is also a need to administer the SAN infrastructure itself, including device management and resource management, despite the lack of industry standards. Many of the management tools provided by individual SAN vendors are still proprietary, working well with their components but less reliably with other vendors.
EMC, Legato, Tivoli and Veritas offer storage management targeted at SANs.
In addition to management over the SAN, the management of SAN infrastructure is also important. A management tool must alert to problems with any part of the SAN, often by drilling down to the storage and networking devices’ own management tools.
Computer Associates, perceiving no single standard in this area, provided an extension to its Unicenter TNG systems management platform so its customers could manage their SANs from the same console as their messaging networks and systems.
New Zealand organisations interviewed about their use of SANs were generally pleased with the results, though pointing to fishhooks in implementation.