Abstract: An alignment data structure is used to map a logical data block start address to a physical data block start address dynamically, to service a client data access request. A separate alignment data structure can be provided for each data object managed by the storage system. Each such alignment data structure can be stored in, or referenced by a pointer in, the inode of the corresponding data object. A consequence of the mapping is that certain physical storage medium regions are not mapped to any logical data blocks. These unmapped regions may be visible only to the file system layer and layers that reside between the file system layer and the mass storage subsystem. They can be used, if desired, to store system information, i.e., information that is not visible to any storage client.

Abstract: I/O bandwidth reduction using storage-level common page information is implemented by a storage server, in response to receiving a request from a client for a page stored at a first virtual address, determining that the first virtual address maps to a page that is a duplicate of a page stored at a second virtual address or that the first and second virtual addresses map to a deduplicated page within a storage system, and transmitting metadata to the client mapping the first virtual address to a second virtual address that also maps to the deduplicated page. For one embodiment, the metadata is transmitted in anticipation of a request for the redundant/deduplicated page via the second virtual address. For an alternate embodiment, the metadata is sent in response to a determination that a page that maps to the second virtual address was previously sent to the client.