Channel takeaway: Scaling a storage area network (SAN) to meet the need of a customer isn't an uncommon task for a VAR supporting a growing enterprise. Making the addition as easy as possible is the responsibility of the VAR. Adding more hardware isn't going to address disaster recovery, migration or future growth. This tip takes into account all the challenges that a VAR faces when scaling a SAN.
Storage area networks (SANs) must scale to accommodate the added demands of more users along with a proliferation of more sophisticated enterprise applications. In the Fibre Channel world, scaling often means adding more and faster switch ports to extend the fabric's bandwidth and connectivity. For example, adding 4 Gb FC ports supports more interconnected storage devices and servers, while enhancing their performance and availability. But IP storage (mainly iSCSI) is a growing area of SAN expansion, using ubiquitous Ethernet network technology to pass storage data between storage devices. This requires the use of IP switches and routers, and can involve the deployment of iSCSI TOE host adapters to offload iSCSI traffic from the local server's CPU.
Consider the rate of storage growth. Storage growth rates will have a profound impact on the technology that is selected. Slow growth often favors traditional monolithic storage systems and fixed port switches where there is a single capital expense and only infrequent upgrades. Rapid growth needs typically favor modular storage systems or blade-based servers and switches which can be expanded quickly. Growth also influences bandwidth, and storage network growth should eventually include upgrades to switch port speeds.
Consider the time table of any expansion. Analysts note that overall storage costs (e.g., disk, port and HBA costs) are declining over time, and more features are always being added. This means a massive scaling project implemented in the near term may actually wind up costing more and offering fewer features than a systematic upgrade effort that takes place periodically over time. This can be true even when factoring in potential savings of upfront bulk purchases. Once you have an accurate knowledge of growth rates, compare product costs and see what makes more financial sense for your organization.
Other important storage scaling considerations for VARs:
- Migration in the scaling process.
- Backup and disaster recovery.
- Changes to management requirements and processes.
- Tracking performance.
Read the rest of Bigelow's article at SearchStorage.com.
This was first published in May 2007