Method for coupling sub-lun load measuring metadata size to storage tier utilization in dynamic storage tiering

A method for metadata management in a storage system, the storage system configured for supporting sub-LUN tiering, the method comprising:

• providing a metadata queue of a specific size, the metadata queue configured for caching metadata for a specific number of sub-LUNs;
• determining whether the metadata for a particular sub-LUN is cached in the metadata queue when the particular sub-LUN is being accessed;
• updating the metadata for the particular sub-LUN when the metadata for the particular sub-LUN is cached in the metadata queue;
• inserting the metadata for the particular sub-LUN to the metadata queue when the metadata queue is not full and the metadata for the particular sub-LUN is not cached in the metadata queue;
• replacing an entry in the metadata queue with the metadata for the particular sub-LUN when the metadata queue is full and the metadata for the particular sub-LUN is not cached in the metadata queue;
• and
• identifying at least one frequently accessed sub-LUN for moving to a higher performing tier in the storage system, the at least one frequently accessed sub-LUN being identified based on the metadata cached in the metadata queue.

A storage system configured for supporting sub-LUN tiering, comprising:

• a higher performing tier;
• a lower performing tier;
• a metadata queue of a specific size for caching metadata for a specific number of sub-LUNs;
• a metadata queue controller configured for managing the metadata cached in the metadata queue and identifying at least one frequently accessed sub-LUN for moving to the higher performing tier, wherein the at least one frequently accessed sub-LUN being identified based on the metadata cached in the metadata queue;
• and
• a metadata queue adjustment module configured for determining a performance level of the higher performing tier and adjusting the size of the metadata queue based on the performance level determined.