Capacity sprawl, in a storage context, is a situation in which multiple, under-utilized or badly managed storage media occupy more overall space than can be justified by actual need.
Capacity sprawl may be confined to a single physical site, but sometimes it is spread across multiple facilities in diverse geographical locations, especially when companies merge or acquire other companies. Over time, administrators lose track of how much storage exists, where it exists, what it contains, and in some cases even who is using it.
Common causes of capacity sprawl are similar to those of server sprawl, such as the purchase and accumulation of servers and computers with high-capacity hard disks, the practice of dedicating servers to single applications, overestimating or overanticipating the actual need for storage, and a natural human tendency to leave data in storage long after it has become obsolete.
Storage and servers are not the only commodities that can develop sprawl issues. The ease with which resources can be acquired, coupled with reluctance to discard them when they have outlived their usefulness, can generate sprawl with e-mail, databases and VMs (virtual machines) that can grow beyond the control, or even the full knowledge, of system administrators without a responsible long-term resource-management policy.