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The law of unintended storage consequences

Recent implementation and subsequent withdrawal of part of VMware's VAAI feature set illustrate the risks in the growing complexity of modern storage

The increasing complexity of modern storage arrays seems to know no bounds. While all of us are understandably excited when hot, new storage features arrive on the scene, it's important to remember that all of them come at a price. Their complexity tends to make these systems harder to troubleshoot -- and harder for storage vendors to test fully before they hit the market.

Each customer has its own way of using a new storage product to meet specific needs, so expanding the feature set multiplies the number of scenarios the vendor needs to test against. It's almost inevitable that something will slip past the folks in QA. That's precisely what happened after the release of vSphere 5.0's new INCITS T10-based VAAI implementation, resulting in VMware hastily telling customers to manually disable the offending feature before it could cause problems.

There's a lot we can learn from this particular case. Storage is no longer an amorphous bucket you pour your data into -- it's a living, breathing entity that can have as much of an impact on your environment as your users or the applications you run. Heavier integration with hypervisors and other software not only enhances the storage's ability to solve problems, but also to create them.