Migrating data from conventional storage systems to a SAN is a major undertaking. To do the job efficiently and with the maximum benefit it is important to decide what data you will migrate and in what order you will move it to the SAN.
The first step is simply to decide which categories of data -- applications, databases or transactional data, etc. -- will be moved first. This is usually a business-strategic decision made in close cooperation with the user communities. The next step is to set priorities for moving the data in each category.
One common way of setting priorities within a category is to move the most active data first since this is the data that will benefit most from the SAN's increased reliability and ease of backup and management. In this approach, the first step is to collect metrics on how often the data is modified using storage resource management tools. Once that is done, the information is mapped backwards onto the logical devices and then the physical devices where the data is stored. With that information, the SAN administrator can decide which file systems and servers' data will be moved to the SAN first.
Sun Microsystems illustrates this process in a white paper titled "Storage Resource Management: A Practitioner's Approach" which is available on the company web site at www.sun.com.
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.
