What you need to know to tune your SAN
Like any other storage system, a SAN benefits from being tuned. However because a SAN is more complex than, say, a RAID array, tuning a SAN is more complex as well. The key to tuning a SAN is information on specific areas of performance. This allows you to identify hot spots and take action on them.
Among the things you need to know to tune a SAN effectively are the throughput rates by device, the average daily throughput, the average hourly throughput and the effect of object size on throughput. Good SAN management software should provide all this information and more.
Two particular parameters, Object size effects, and throughput rate by device, are particularly important. Typically a SAN is optimized to move data in fairly large blocks, which is one of the reasons using another channel for control information improves SAN performance. However the size of the objects being moved over the SAN can vary significantly with the application. In some cases performance falls off quickly when the design object size and the actual object size differ. Knowing the throughput rate on devices is the first step in locating underperforming or misconfigured devices that are slowing down the SAN. It is a basic diagnostic for SAN tuning.
IBM discusses the subject in its red book on "Storage Networking Virtualization: What's It All About", which is available at
Rick Cook has been writing about mass storage since the days when the term meant an 80K floppy disk. The computers he learned on used ferrite cores and magnetic drums. For the last twenty years he has been a freelance writer specializing in storage and other computer issues.
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Storage Area Networks: Designing and Implementing a Mass Storage System, 1/e
Author : Ralph Thornburgh and Barry Schoenborn
Publisher : Prentice Hall
Published : Sep 2000
Every month, enterprises require more information, delivered faster, with greater reliability--and traditional data storage methods no longer suffice. Enter the Storage Area Network (SAN), which can store enormous amounts of data, serve it at lightning speed, scale to meet accelerating growth, and deliver unprecedented reliability. Now, there's a complete guide to SAN technology for every IT professional and decision-maker. Storage Area Networks covers it all: key concepts, components, applications, implementation examples, management, and much more.
This was first published in July 2001