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Are you a Star Wars fan? Then, you probably already know what the dark side of the force is. But have you ever heard of the dark side of storage? Also called Dark Storage, this notion refers to allocated but unused storage capacity which often results in storage waste and useless spending on storage hardware. Dark storage would represent roughly 30% of storage resources. This growing plague strikes indiscriminately large, medium, or small-sized enterprises across the galaxy… well, at least the globe. It’s there around you and you may not even know it.

Jedi, let’s try to understand the nature of our enemy and let’s see how the Sentry Software’s connectors for BMC TrueSight Capacity Optimization can help you eliminate it. It’s time to take your lightsaber to defeat the dark side of storage!



Dark storage is synonym of storage inefficiency. The term was firstly introduced in 2008, and is yet today more relevant than ever. Indeed, Gartner has indicated that only 20% to 40% of storage capacity was being effectively used.

The dark storage menace arises in a subtle manner. Normally, the usual process is as follows: storage administrators configure storage volumes that are then mapped to a host server, recognized by the hardware, presented as volumes, and finally utilized by applications and users. But in reality, at each stage of this process, storage inefficiency can exist and prevent the available space to be optimally allocated resulting in dark storage.

Dark storage can frequently be attributed to human error: administrators who do not always follow all recommendations, or simply decommission their older storage hardware without afterwards doing the appropriate follow-up related to it. Sometimes, the administrators who are in charge of storage and those who are responsible for servers can be different people and a firewall may exist between them. Storage admins can consequently hardly know the actual available storage capacity in their data center and dark storage could be left undetected.

Other factors can contribute to making the detection of dark storage even more complex: capacity management made through thin provisioning on disk arrays, virtualization that can obfuscate capacity management by adding an abstraction layer to storage resources, compression, de-duplication, etc.

To put it briefly, available storage capacity often exists but remains invisible to users as well as admins. And therein lies the problem: companies may engage wasteful spending in ordering new storage equipment instead of making the most of their existing idle storage and maximizing storage utilization.

Small wonder then that storage admins and capacity planners wish to be able to detect dark storage and look for powerful tools in order to reduce the part of storage and money wasted due to inefficient capacity allocation. 


Jedi, the time has come to join the light side of the force…



Various capacity management tools that are capable of detecting dark storage and other utilization-related issues exist but, contrary to TrueSight Capacity Optimization used in conjunction with Sentry’s ETLs, these solutions rarely cover all existing storage systems.

Sentry’s ETLs for TrueSight CO are designed to help administrators detect unidentified dark storage and better assess their storage utilization for a wide range of platforms: EMC, NetApp, Hitachi, Dell, HP 3PAR, etc.

By default, several TrueSight CO dashboard views are available to let admins quickly monitor the overall capacity for all their storage systems and verify the resource utilization for volumes. IT admins can for example easily identify unmapped or unused volumes allocated to decommissioned servers and then take the necessary actions to reclaim unused storage capacity.


Reclaiming Unused Storage Capacity by Identifying Unmapped or Unused Volumes


In addition, Sentry’s Storage Capacity Views and Reports for TrueSight CO offers out-of-the-box reports integrating numerous analyses and models on storage allocation. These reports include valuable graphs displaying for example: Storage Capacity, Available Capacity, Consumed Capacity, and Subscribed Capacity metrics for each available storage pool.


Generating Reports with Storage Capacity Views and Reports for TrueSight CO.png

Generating Reports with Storage Capacity Views and Reports for TrueSight CO


But there is more, with Sentry’s Storage Capacity Optimization solution, administrators can:

  • Identify the capacity actually consumed per host and know which storage system or which storage pool this capacity has been allocated from.
  • Determine which storage pool from which storage system is best suited to host the storage capacity required.
  • Analyze storage capacity utilization at the storage systems and storage pools levels to better control storage costs.
  • Prevent oversubscription situations and unrecoverable data loss and corruption.
  • Guarantee enough remaining space to answer allocation requests as quickly as possible and know which disks can be used to extend the capacity of storage pools.

With all this information at hand, storage administrators and capacity planners will be able to achieve smooth storage administration and plan for additional storage capacity only when really needed.



By now, you should be more familiar with dark storage and know how to defeat it. Ensuring enough remaining storage space to answer allocation needs and guaranteeing that consumers use allocated storage efficiently is not an easy task. Nevertheless, the ability to recognize and report dark storage contributes to making Sentry’ ETLs for TrueSight Capacity Optimization the best existing solution to simplify any storage manager’s job. Recognized for its professional expertise and technical excellence, Sentry and its renowned Storage Capacity Optimization solution will ultimately help you:

  • Reduce waste in allocated but unused storage capacity
  • Lower storage costs by increasing utilization
  • Anticipate future storage requirements
  • Make more timely purchases


And remember that with Sentry and BMC, the Force will be with you… always.