Virtual disk drive system and method

A method of data progression in a disk drive system, comprising:

• classifying each of a plurality of storage devices based on the cost;
• checking data on the storage devices to determine whether there is data to be moved from one classification of storage device to another;
• and
• moving data stored on one or more storage devices of one classification to one or more storage devices of another classification;
• wherein data is moved to a lower cost storage device if the data has not been recently accessed.

A method of data progression in a disk drive system, comprising:

• classifying each of a plurality of storage devices based on the cost;
• checking data on the storage devices to determine whether there is data to be moved from one classification of storage device to another;
• and
• moving data stored on one or more storage devices of one classification to one or more storage devices of another classification;
• wherein data is moved to a lower cost storage device if a substantial portion of the storage space on a higher cost storage device is used up.

A disk drive system manager, comprising:

• means for classifying each of a plurality of storage devices based on the cost;
• means for checking data on the storage devices to determine whether there is data to be moved from one classification of storage device to another;
• and
• means for moving data stored on one or more storage devices of one classification to one or more storage devices of another classification;
• wherein data is moved to a lower cost storage device if a substantial portion of the storage space on a higher cost storage device is used up.