What's the Best Way to Set Up Tiered Storage?

Start with the basic questions that drive storage infrastructure development: What are the true requirements of the business and their applications?

Setting clear application requirements for performance, availability, and recoverability will determine the appropriate tiered storage environment whether it is “tiering in a box” or a more traditional approach. For instance, you want to keep important transactional information on high-end storage and less frequently accessed information on cheaper but lower performance storage. You also need to take into account retention rules governed by compliance regulations.

Once you define your requirements, you can take inventory of your current storage assets and determine which tiers you already have and which need to be developed. The resulting architecture will define your new "tiered storage reference architecture."

This architecture needs to be validated with application stakeholders and other infrastructure stakeholders to confirm its compatibility and support in the current environment.

Examples of tiers would be Fibre Channel disk for Tier 1 or highest performance storage; high-capacity SATA drives for less frequently accessed Tier 2 storage; and perhaps content addressable storage (CAS) or tape for long-term archived data. You may need more tiers depending on your data requirements.The next step for the storage administrator is to determine how and when the new architecture will be deployed and how data that resides on current arrays will be migrated to the new infrastructure.

After deciding on implementation and migration, the next critical step is to develop clearly defined policies that drive the allocation of new data to the appropriate storage tier. These policies must address how the information is stored and on what medium, how the data is protected (through backup or replication), and how long it shall be retained.

The final and perhaps most important step in the process is implementing a mechanism to collect, track, and report key performance indicators that support your new data allocation strategy. This may require you to evaluate and test new applications to carry out these tasks. These applications can view file systems, find old and infrequently accessed files, and produce reports on access patterns, file types, and duplicated files.

— Tim Arland, Principal Consultant for Storage Solutions, Forsythe Solutions Group Inc.