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Where should storage intelligence reside?

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Where is the best place to embed storage intelligence into the network? The following guidelines will help you decide:

On The Switch. For environments with heterogeneous storage arrays and servers, minimal anticipated growth and a small team of administrators, placing storage intelligence on the switch makes sense. Products from smaller companies may be acceptable, but more established shops will probably want to consider products from EMC, IBM and Veritas as they become widely available.
On an Appliance. Appliances make sense for heterogeneous array, server and switch environments where growth is dynamic and unpredictable. Appliances can fit into existing deployments without forklift upgrades. Larger shops new to this space may want to experiment with products from Candera, DataCore, FalconStor, Softek and Troika Networks. Once familiar with the technology, consider solutions from EMC, IBM or Veritas as they're more likely to fit into existing infrastructures with less disruption.
No intelligence in the network. There are good arguments for keeping switches stupid. With switches prices as low as $200 per port, keeping intelligence on the host and storage arrays is a cost-effective option for relatively small environments with just one storage array or servers with the same operating system.
Growing and merging storage area networks (SANs) create levels of complexity that many of today's baseline Fibre Channel (FC) switches were never designed to handle. Deployed to referee connectivity between servers and storage, switches need more intelligence to manage the multifaceted performance, storage and security issues that large fabrics increasingly need to address.

Simply put, switches bear the brunt of the changes in storage networks. They must simultaneously monitor and prioritize bandwidth for critical applications, handle storage management functions and secure access for all devices attached to the SAN. Putting these services in switches gives users multiple benefits:

  • A central point of administration for storage, performance and security management functions
  • Simpler storage management
  • Stronger security
  • Better performance and availability of critical applications
Yet as switches take on these responsibilities, users also need to consider the following:
  • Are switches the best choice to house storage and security functions? Or are customized appliances better suited?
  • How will these technologies impact the performance of your critical applications?
  • How compatible are these vendors' advanced switch technologies with your storage environment?
Answering these questions will be complicated by the intangible factors that also come into play. For example, who will manage functions within the switch and under what circumstances? Not everyone understands the benefits of moving these technologies to the switch, so incorrectly configuring any of these functions can create its own set of problems. Even if policies are defined, enforcing them will be difficult because implementing networking, security and storage functions on a single switch may cross existing departmental and political lines.

Users must also assess if they should use existing technologies or deploy new ones. For example, Brocade Communications Systems Inc., Cisco Systems Inc. and McData Corp. switches integrate security and volume management technologies from companies such as EMC Corp., IBM Corp. and Veritas Software Corp. However, a new switch vendor like Maxxan Systems Inc. ships its own storage and security products.

Magnifying the problem, the capabilities that smart switches offer vary significantly from vendor to vendor. For example, Sandial Systems' Shadow 14000 FC switch offers users the ability to monitor performance and then dynamically allocate bandwidth based upon predefined QoS policies. Both Maxxan's MXV320 and Cisco's MDS 9000 family of switches can incorporate virtualization blades into their switches from third-party providers like FalconStor Software Inc., IBM and Veritas. Still others like Computer Network Technology Corp.'s UltraNet Multi-service Director (UMD) offer users the ability to turn on RADIUS authentication that enables switches to verify the authenticity of servers logging onto the FC SAN. What follows is a look at who offers what, how the features work and which ones you need and when.

This was first published in August 2004

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