Chapter 10. Advanced features for storage efficiency 429
Figure 10-17   Selecting capacity setting
After the copies are fully synchronized, the original volume copy is deleted automatically.
As a result, compressed data is on the volume. This process is nondisruptive, so the data 
remains online and accessible by applications and users.
This capability enables clients to regain space from the storage pool, which can then be 
reused for other applications.
With the virtualization of external storage systems, the ability to compress stored data 
significantly enhances and accelerates the benefit to users. This capability enables them to 
see a tremendous return on their Storwize V7000 investment. 
On the initial purchase of an Storwize V7000 with Real-time Compression, clients can defer 
their purchase of new storage. When storage is needed, IT purchases a lower amount of the 
required storage before compression.
For more information about volume migration for compressed volumes on standard pools to 
DRPs, see “Migrating to and from DRP” on page 425.
10.6  Saving estimation for compression and deduplication
This section provides information about the tools that are used for sizing the environment for 
compression and deduplication. 
10.6.1  Evaluate compression savings by using IBM Comprestimator
IBM Comprestimator is an integrated GUI and CLI host-based utility that estimates the space 
savings that are achieved when compressed volumes are used for block devices. This utility 
provides a quick and easy view of showing the benefits of the use of compression. The utility 
performs read-only operations and therefore, does not affect the data that is being stored on 
device. 
If the compression savings prove to be beneficial in your environment, volume mirroring can 
be used to convert volumes to compressed volumes in the data reduction pools.