Storage management for fine grained tiered storage with thin provisioning

A method for garbage collection of data for memory management, comprising:

• providing a first logical device;
• providing a second logical device having a table of information that maps sections of the first logical device to sections of at least two storage areas, the table of information being stored in the second logical device;
• evaluating characteristics of data associated with at least one of the sections of the first logical device;
• copying the data associated with the at least one of the sections of the first logical device between the at least two storage areas from a first location to a second location according to a policy and based on the characteristics of the data, wherein, after copying the data, a copy of the data is in the first location and a copy of the data is in the second location, wherein the table of information is stored independently of the data copied between the at least two storage areas, wherein the table of information identifies sections of the second logical device for which no corresponding physical space of the at least two storage areas has yet been allocated, and wherein the sections of the second logical device for which no corresponding physical space of the at least two storage areas has yet been allocated are identified as being available for use in response to a request for available space received at the second logical device;
• retaining the copy of the data in the first location;
• and
• maintaining, using the table of information, a delete list that identifies the copy of the data in the first location as a candidate for deletion.

A computer storage device, comprising:

• a plurality of interconnected directors, wherein at least some of the directors handle reading and writing data for the computer storage device;
• a plurality of disk drives, coupled to at least some of the directors, that store data for the computer storage device;
• and
• computer software, stored on a computer readable storage medium of at least one of the directors, having executable code that provides a first logical device;
• executable code that provides a second logical device having a table of information that maps sections of the first logical device to sections of at least two storage areas, the table of information being stored in the second logical device;
• executable code that evaluates characteristics of data associated with at least one of the sections of the first logical device;
• executable code that copies the data associated with the at least one of the sections of the first logical device between the at least two storage areas from a first location to a second location according to a policy and based on the characteristics of the data, wherein, after copying the data, a copy of the data is in the first location and a copy of the data is in the second location, wherein the table of information is stored independently of the data moved between the at least two storage areas, wherein the table of information identifies sections of the second logical device for which no corresponding physical space of the at least two storage areas has yet been allocated, and wherein the sections of the second logical device for which no corresponding physical space of the at least two storage areas has yet been allocated are identified as being available for use in response to a request for available space received at the second logical device;
• executable code that retains the copy of the data in the first location;
• and executable code that, using the table of information, maintains a list that identifies the copy of the data in the first location.