Research On Data Management Policy Of Object-based Storage System

With the increasing demand of high data throughput, highly parallel data transfer and highly scalable storage system, especially in the field of super computing, the traditional storage system cannot meet the requirements any longer. With the driven needs of applications, storage system must have changes. A new storage model, Object-based Storage System, OBS for short, comes up. The file system used in the OBS, is a distributed file system. The storage management model down to the intelligent devices, which is different from the traditional one. The Object-based Storage Device, OSD for short, which is the core part of the OBS, carries the data in the OBS and also takes charge of the management of space in the physical disc.The performance of the single OSD can be improved via two methods. The first one is to design a new Object-based Storage Device Controller, OSC for short. OSC is based on the switch fabric architecture. And two CPUs with Xscale architecture are included in OSC. The switch fabric breaks through the bottle-neck of I/O system, and implements the parallel I/O access in the hardware level. The second one is the management of disc space. XOBFS, which stands for eXtensible hashing Object-based Storage File System, uses the fixed-block allocation policy and manages the free space with the bitmap method. And XOBFS organizes the metadata in extensible hashing structure. All of this cannot make fragmentation after long term running. The performance does not degenerate as the file system ages.By collecting blocks of same size into regions, XOBFS can avoid the system fragmentation as the system ages. However, on the worst condition, there would be a waste of about 10 percent of total disc space. For organizing and managing data effectively, the object attributes are included in XOBFS. Compared with the traditional file systems, the throughput of XOBFS is the best one. XOBFS provides an effective method for storage management in OSD.