What is tiered storage?
Tiered storage is a data storage method or system that consists of two or more types of storage media, e.g. B. CDs, DVDs, hard drives, optical discs, hard drive arrays and magnetic tape drives. The type of media used to store a category of data is determined by several factors including media cost, data availability requirements, data recoverability, etc.
Tiered storage and hierarchical storage management (HSM) are sometimes referred to as interchangeable. Typically, however, HSM refers to an automatic system of data transfer on a number of media types depending on the frequency of use. For example, data stored on drives can be automatically transferred to magnetic tape when it has not been used for a period of months.
Tiered storage can be two tiers when the media types available are just hard drives and tapes; Each of these levels includes differences in four main attributes, namely price, performance, capacity and function.
New technologies and old technologies can represent the types of media available. This would prescribe two levels as each would involve differences in all four attributes. Similarly, high-performance storage devices and slower, low-performance devices can also impose two tiers.
Tiered storage requirements are also determined by functional differences, such as: For example, the need for replication for security purposes and the rapid recovery of data through hard disk drive arrays. In this case, data is stored for two different functions; Therefore, at least two levels would be appropriate. Two very widespread levels, which are substantially separated from one another by the access speed, are the levels of magnetic disks and tapes; Another common two-stage system is a magnetic disk and an optical disk.
Depending on company-specific data storage guidelines, some manufacturers' products can blur the differences between tiered storage and HSM. They provide software to implement the policy by automatically allocating or transferring data stores depending on changing data, frequency of use, and available storage media.