File-based hybrid file storage scheme supporting multiple file switches

摘要

In an aggregated file system, a file may begin with a set of stripe fragments all in the RAID-5 scheme in order to take advantage of the RAID-5 scheme's storage efficiency. After that, when one of the fragments is accessed by a file switch, it will be duplicated into the data mirroring scheme. The file's corresponding metadata server maintains a data structure, e.g., a bitmap, indicating which fragments have been duplicated into the data mirroring scheme. In other words, the file, at this moment, exists in a hybrid scheme. A file consolidator running on the metadata server is triggered at a predefined time to copy the fragments from the data mirroring scheme back to the RAID-5 scheme, This file consolidator also updates the bitmap to reflect the changes to the file's scheme change. This hybrid scheme is expected to increase the I/O capacity of the conventional RAID-5 scheme and the storage usage of the conventional mirroring scheme.