Understanding hierarchical data storage management

Data storage management is a complex task that it involves a lot of hardware and software along with some techniques to improve the efficiency of the system as a whole in an organization. If we consider the hardware alone there are many types of storage that we can think of, like, hard disk drive, optical disks, and magnetic tape drives. Of these the hard disk is faster than the other two. So you have to decide which of these should be used for storage of your organization data. There comes hierarchical data storage management.

Having all your data in a hard disk would be costly on ‘per byte stored’ basis. Not all the organizations can afford to this kind of storage. Moreover it is not necessary to store all the data in a hard disk. Instead you can opt for low cost storage like optical discs and magnetic tapes. In most of the organization the bulk of data is stored in such low cost devices and then later on moved to faster devices when needed.

In hierarchical storage management, the system monitors for the usage pattern of the data. The data which are frequently accessed are stored in hard disks. If the system finds any data that is not accessed for a certain period of time then that data is moved to slower storage devices. Such movement of data to different levels of storage is managed by the hierarchical storage management systems.

If a user accesses the data stored in a slower device, then that data is moved to the hard disk. The user would not find any difference in the way the system works, since only data that is rarely used are in the slower devices. One of the other advantages of such systems is that you can store data more than the capacity of the disk drive since multiple storage devices are there. Since data is stored in different tiers this type of data storage management is also called as the tiered data storage management.