Planning for data tiering

Plan your data tiering implementation by understanding requirements, validation checks, and filesystem configuration options.

Before planning for data tiering, ensure you have:

  • IBM Storage Scale 6.0.1.0 or later installed
  • Understanding of storage pool concepts
  • Fast storage devices available (NVMe, SSD)
  • Knowledge of your workload access patterns

Before implementing data tiering, you must plan your storage pool configuration and understand the requirements and limitations. Proper planning ensures optimal performance and cost efficiency.

Requirements for the fast tier pool

The data tiering feature requires a fast tier pool in the file system.

The following requirements must be met:
  • Create the pool with the fastTierPool=yes attribute.
  • Define the pool during file system creation or while adding disks.
  • Use high-performance devices such as NVMe or SSD drives.
  • Configure the pool as either dataOnly or dataAndMetadata.
  • Ensure that only one fast tier pool exists in the file system.

Requirements for the file system

A file system that uses data tiering must contain the following storage components:
  • System pool:

    Required for metadata storage. The system pool can also act as the fast tier pool if it is configured as dataAndMetadata.

  • Regular data pool

    Required to store blocks that are outside the configured fast tier range. This can be the system pool or a separate data pool.

  • Fast tier pool

    Required for data tiering. Stores the initial file blocks that fall within the configured threshold.

Validation and limitations

These are the operational limitations:
  • Existing pools cannot be modified into fast tier pools after creation.
  • A fast tier pool designation cannot be modified.
  • Only one fast tier pool is allowed per file system.
  • Migration policy rules that use fast tier ranges fail validation if no fast tier pool exists.
  • Data tiering settings apply only to regular files, not directories.
  • File systems that use both the fastTierPool and performance pool are not supported.
  • If the fast tier range changes after a snapshot is created, a file might be placed incorrectly when it is restored from the snapshot by using the mmrestorefs command. If you do not need to restore the fast tier range, specify the --suppress-external-attributes option when you run the mmrestorefs command.