Whether it's for performance or capacity improvements, the goal of tiered storage is simply to get data on the appropriate storage system. For SMBs, three tiers typically suffice: primary, which is generally a midrange
Having different "types" of storage does not mean there are different "tiers." A company that does a disk-to-disk-to-tape backup will often back up their data from their fast-access disk to a high-capacity, less-expensive disk, and then copy it to tape. This is just simply using different storage types to get a job done.
When referring to tiers of storage, each of the different storage types is integrated together, and data exists on each storage tier based on policies established by the business. The data is then stored to/accessed from the tier automatically through software that supports the policies.
A time-based file system archiving solution exemplifies how these tiers work together. When data is saved, the file system may immediately make multiple copies of the file on the different tiers. The policy set could be that after 30 days of a file not being touched, its space is to be freed up from the top storage tier. After 90 days of it not being accessed, its space is to be freed up from the second tier. Then, after seven years (or whatever retention time a company may have for their data) the file is to be removed from the third tier.
During this time, the file name still exists in the file system, but its physical space is only where the policy allows it to be. If someone wants to access the file on the 45th day, it will come from the second tier of storage. It may be a little slower, but it is on a less-expensive tier of storage, which is more in line with the value of the data. Policies can often be set based on file owner, name, size and even type.
Tiered storage solutions fit well for email applications. Employees may get a lot of personal emails sent to them, but if the employees are saving large PowerPoint files and other attachments, those may very well eat up a lot of the space on the most expensive tier of storage. A policy stating that all PowerPoint files greater than 2 MB will be saved to the second or third tier of storage will still keep them available, but will not consume the space of the fastest and most expensive storage tier, which is most likely needed for mission-critical application data.
Because most hardware vendors can provide systems with different drive types, the difficulties related to storage tiering aren't usually associated with the physical components. The challenge exists in prioritizing the data based on business needs, then implementing those with the right software solution to have an automated solution that takes advantage of the cost benefits of the different tiers. This can often involve months of meetings with different department heads and their superiors. Then, finding and evaluating the right software that can implement those policies once this is completed, will also take time.
When done properly, a tiered data storage solution can help SMBs keep their data growth in check and acquire the right type of storage based on their needs. Businesses with one tier of storage for everything often find themselves running out of space and buying expensive disk solutions because non-business-critical data is taking up all of the space.
Buying different storage types is easy. Implementing a tiered storage solution takes not only the storage types, but planning and prioritizing based on the needs of the company. SMBs that want to lower the cost of managing storage assets should seriously look at a tiered storage solution. Before discussing price and a provider, IT management and other department heads should determine what data is critical, what data needs the fastest access possible, and what data, though still available, can stand to be accessed a little slower. Once this is determined and there is buy in all around, implementation will be much easier.
About this author: Enterprise Management Associates (EMA) Senior Storage Analyst, and Ask Mr. Storage writer, Curtis Breville is a storage industry veteran with over two decades of experience ranging from technical roles with small businesses to consulting, architecting solutions for, and selling to some of the largest and most complex data centers in the world.
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This was first published in April 2009