Use cases for capacity saving

The results of enabling the capacity saving functions of deduplication and compression depend on the properties and access patterns of the stored data. In addition, when capacity saving is enabled, some storage behaviors are different from conventional behaviors because of the increase in load of storage controller processing caused by data scanning and garbage collection by data update. Before implementing capacity saving, you need to confirm whether it should be applied to your specific storage environment.

The following table lists several storage use cases and describes the application of capacity saving to each use case.

Use case

Settings

Description

Office

Deduplication and compression

Because there are many identical file copies, deduplication is effective.

VDI

Deduplication and compression

Deduplication is very effective because of OS area cloning.

Database (TPC-H)

Compression

Deduplication is not effective because the database has unique information for each block.

For a database that has many data updates, garbage data is increased, so it is not suitable.

Database (TPC-C)

Compression

Image/video

Not suitable (Disable)

Compressed by application.

Backup/archive

Deduplication and compression

Deduplication is effective between backups.

Caution
  • I/O performance to data with compression and deduplication is degraded. Verify the performance by utilizing best practices or Cache Optimization Tool (COT) tool before using the capacity saving function.
  • Because approximately 10% is used for metadata and garbage data, capacity saving should be applied only when the result is expected to be 20% or higher.
  • In deduplication and compression, processing is performed per 8 KB. Therefore, if the block size of the file system is an integral multiple of 8 KB, capacity saving is likely to be effective.
  • The capacity saving function is not a good fit for high-write workloads. If the write workload rate is higher than garbage collection throughput, Cache Write Pending increases, causing performance degradation. Contact Hitachi Solution Support Center to determine the garbage collection throughput for your configuration.
Parent Topic
  • Capacity saving function: data deduplication and compression

    When the capacity saving function is in use, the controller of the storage system performs data deduplication and compression to reduce the size of data to be stored. Capacity saving can be enabled on DP-VOLs in Dynamic Provisioning pools. You can use the capacity saving function on all drive types, including data stored on encrypted flash drives and external storage.