Hierarchical defragmentation of resources in data centers

One or more non-transitory computer-readable storage media storing instructions that, when executed by a processor, cause the processor to:

• at a device in a cloud computing system, the cloud computing system comprising a plurality of servers deployed in a plurality of respective racks, wherein the respective racks are deployed in a pod of a data center, determine for each server in the plurality of servers a number of free resource slots available thereon and a number of resource slots in an idle state by adding to a free pool free resource slots and adding to a move pool resource slots that are in the idle state;
• determine whether the number of free resource slots in the free pool for a first server in the plurality of servers is greater than a predetermined threshold, the predetermined threshold being indicative that the first server is a candidate to be powered down;
• when the number of free resource slots in the free pool for the first server is greater than the predetermined threshold, identify a second server in the plurality of servers with sufficient resource slots thereon to accommodate the number of resource slots in the idle state that are in the move pool for the first server;
• and
• cause the resource slots in the idle state on the first server to be migrated to the second server,
• wherein the second server is selected based on a round robin technique such that each server among the plurality of servers is a candidate to be selected as the second server for a predetermined amount of time.

An apparatus comprising:

• a network interface unit configured to perform communications over a network;
• a processor configured to be coupled to the network interface unit, wherein the processor is configured to:
• determine for each server in a plurality of servers a number of free resource slots available thereon and a number of resource slots in an idle state by adding to a free pool free resource slots and adding to a move pool resource slots that are in the idle state;
• determine whether the number of free resource slots in the free pool for a first server in the plurality of servers is greater than a predetermined threshold, the predetermined threshold being indicative that the first server is a candidate to be powered down;
• when the number of free resource slots in the free pool for the first server is greater than the predetermined threshold, identify a second server in the plurality of servers with sufficient resource slots thereon to accommodate the number of resource slots in the idle state that are in the move pool for the first server;
• and
• cause the resource slots in the idle state on the first server to be migrated to the second server,
• wherein the second server is selected based on a round robin technique such that each server among the plurality of servers is a candidate to be selected as the second server for a predetermined amount of time.