| 摘要 |
A system and method for improving communication between a storage area network ("SAN") and a network attached storage ("NAS"). The NAS, implementing a file system, may be configured to create a message to inform an underlying SAN utilizing a list of freed blocks in response to a file and/or directory deletion by a client. The NAS outputs the freed block message to the SAN. The SAN may be configured to maintain a current free block table (or current free block list). The SAN may be further configured to update the current free block table in response to receiving the freed block message from the NAS. As a result, any block listed on the current free block table may be flushed from the SAN, marked as unused by the data storage system or may be marked as allocated but unused. If the SAN marks blocks as unused, the unused blocks are eligible for migration to relatively less expensive storage within the SAN. The sending of the freed block messages from the NAS to the SAN can be done in an "out of band" fashion, without changing the native interface between the NAS and the SAN. These messages do not affect the correctness of the data sent from the SAN to the NAS, only the performance of the responses from the SAN to the NAS.
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