Storage Capacity KPIs

When I first started working with Distributed Storage for many years I worked with Asset Management and various other departments to answer the question, “How much storage do we have available and how much is used?”. The problem was depending upon how the numbers were sumarized and presented various impressions were left with management that didn’t communicate a complete picture. This invariably led to inaccurate assumptions that required many subsequent explanations. If we are to overcome these problems and communicate a clear picture of storage capacity we must address several issues.

The first issue to be addressed is whether to report storage capacities as raw capacity or usable capacity. The simplest method is to report raw but since these numbers do not take into account protection and management overhead service delivery management is tempted to think that more storage is available then what is available in reality. If these overheads aren’t taken into account when projecting future demand the projected supply may be overstated. For this reason it is probably best to provide facilities for reporting both raw numbers which will be used more in the day to day support and usable numbers for planning and estimation purposes.

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