Planning for deduplicated volumes

A deduplicated volume or volume copy can be created in a data reduction pool (DRP). When you implement deduplication, you must consider specific requirements in the storage environment.

You can create deduplicated volumes in an I/O group when no compressed volumes or volume copies are in regular storage pools (that is, when real-time compression is in use on that I/O group). Data reduction pool compressed volumes can coexist with real-time compressed volumes in the same I/O group.

To use deduplication on the system, the hardware must have at least 32 GB of memory.

You can migrate any type of volume from a regular storage pool to a data reduction pool. You can also migrate any existing real-time compressed volume to a data reduction pool. You can use volume mirroring to migrate data from a volume in a regular storage pool to a deduplicated volume in a data reduction pool. You can use the Add Volume Copy page in the management GUI or use the addvdiskcopy command to create a deduplicated, volume copy of an existing volume in a standard pool in a data reduction pool .

The following software and hardware requirements are needed for deduplication. There are also update and performance considerations.
  • Nodes must have 32 GB memory to support deduplication.
  • Nodes that have more than 64 GB memory can use a bigger deduplication fingerprint database, which might lead to better deduplication.
  • You can use the Data Reduction Estimation Tool (DRET) to estimate how much capacity you might save if a standard volume that a host can access was a deduplicated volume. The tool scans target workloads on all attached storage arrays, consolidates these results, and generates an estimate of potential data reduction savings for the entire system.

    Go to https://www-945.ibm.com/support/fixcentral/ to search under IBM Spectrum Virtualize to find the tool and its readme.

    Note: The Data Reduction Estimation Tool also provides some analysis of potential compression savings for volumes; however, it is recommended that you also use the management GUI or the command-line interface to run the integrated Comprestimator Utility to gather data for potential compression savings for volumes in data reduction pools.

Real-time compression and deduplication are not supported in the same I/O group. However, data reduction compression and deduplication might be supported on certain platforms.

Table 1 details the features that are supported on each platform.
Table 1. Supported compression features
Product Platform Node/canister memory (GBs) Supported features
Real-time compression DRP Compression Deduplication
SAN Volume Controller 2145-SV1/ 64/128/192/256 Yes1 Yes Yes1 Yes
IBM Spectrum Virtualize Any Yes (dual CPU only) Yes Yes2 Yes (greater than 32 GB required)
32/64 Yes1 Yes Yes1 Yes
Note: Real-time compression and data reduction compression is assumed to be supported within the same I/O group at the same time, unless the platform does not support compression or the matrix indicates otherwise.
  • 1 - Requires compression hardware for new systems.
  • 2 - Compression in data reduction pools is supported by single or dual CPU. Dual CPU real-time compression restriction still applies. Does not support DRP compression and real-time compression in the same I/O group at the same time.