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If it ain't broke ...
Users may resist a tiered storage infrastructure. Storage admins may be enthusiastic about the new tiers of storage and the possible infrastructure improvements, but to application owners, new storage means change and change means risk. If an app has been running on tier-one storage for years, why would a user want to move it? The good corporate citizenship argument can go only so far, and the outages required for data migration, along with the ensuing risks of disruption and possible performance degradation, are deal killers. Therefore, their attitude is likely to be "If it ain't broke, don't break it!"
Another consideration is the increased complexity introduced by having to manage a new set of devices. Unfortunately, common storage management tools are still not available, so it's necessary to manage each technology to some degree with its own set of tools. Understaffed storage teams may be taxed by the demands of developing sufficient skill levels to effectively leverage the new technology.
The operational cost impact of additional tiers isn't often properly factored in. Of the various components making up total cost of ownership, ongoing management and operations can dwarf the capital component. So, hardware savings might be erased by increased operational expenses. At the very least, the hardware cost delta between tiers must be substantial enough to make it worth the additional complexity. If not, you're spinning your wheels.
A successful business case for tiered storage needs to consider user acceptance, operational impact and significant, achievable cost savings. Too often, the tiered storage decision is predicated on a Field of Dreams mentality--if you build it, they will come. The truth is that revenue-producing business units often trump IT, a functional cost center. While some IT organizations may be able to dictate standards, in many cases they're the ones who are dictated to and therefore need to provide a more compelling business justification.
This was first published in May 2006