Deduplication and compression: assess capacity savings on your data

The same data in less physical space

Deduplication stores one copy of repeated blocks, while compression represents unique data more compactly. With suitable data, these technologies help accommodate more volume on existing drives and inform expansion planning. For procurement, the key question is the reduction ratio achieved by the intended workload.

Include virtual-machine images, databases, media files and already compressed copies in proportions representative of the operating environment. Evaluate each class separately. The stage at which encryption occurs also matters because the form of the data reaching the array affects reduction opportunities.

Conditions that make PoC results comparable

How to interpret the reduction ratio

In an illustrative calculation, 10 TiB of logical data occupies 4 TiB of physical space for the same dataset: 10/4 gives 2.5:1. Measure logical and physical space at the same time, using the same dataset boundary and units. This ties the result to a specific data class.

When comparing system metrics, check what each formula includes. Allocated but unused space and blocks shared by snapshots may appear in different accounting metrics. Separate those effects from deduplication and compression so that the same benefit is counted once.

From measurement to purchase and expansion planning

Follow the initial load with observation across the data-change and retention cycle. Results by data class support conservative, expected and favourable growth scenarios. These scenarios help size the initial drives, headroom and future expansion requirements.

Acceptance criteria include the sample, measurement method and required outcome. Licence quantities follow the product’s accounting rules and do not automatically change with a higher reduction ratio. If a guarantee programme is included, assess its written data and configuration eligibility conditions alongside the purchasing requirements.