Patent ID: 7870172
Filing Date: 2011-01-11
Classification: G06F

Abstract:
1. A system comprising: a storage subsystem having a plurality of mass storage devices, each of the plurality of mass storage devices having a first contiguous region and a second contiguous region, the storage subsystem including a single hybrid file system to store data in a log-structured file system format, in which a data block is written to a new physical location when it is modified, in the first contiguous region of a mass storage device of the storage subsystem and to store a replica of the data in an extent-based file system format, in which a data block is written to a physical location on which it was previously stored when it is modified, in the second contiguous region of the mass storage device, wherein the hybrid file system assigns a single file block number to the data, the file block number having a mapping to a first volume block number dictated by the log-structured file system format and a mapping to a second volume block number dictated by the extent-based file system format, and wherein the hybrid file system uses the mappings to determine whether to access the first volume block number or the second volume block number to fulfill a read request; a memory including instructions for a hybrid file system manager; and a processor, connected with the memory, to execute the instructions for the hybrid file system manager, wherein the instructions cause the processor to store the replica subsequent to changes in the data stored in the log-structured file system format in response to detecting that the data stored in the log-structured file system format exceeds a threshold of potential fragmentation, the instructions further to cause the processor to receive a read request for the data, to make a determination to read the data in the log-structured file system format if the replica is not stored in the extent-based file system format, and to make a determination to read the replica of the data in the extent-based file system format if the replica of the data is stored in the extent-based file system format.