Design And Implementation Of File System In Object Storage Device

With the exploding incensement of digital information, Storage devices have been separated from the server as an independent storage carrier. As the information resource of intelligent storage management unit, Object-based storage device (OSD) is a platform that is based on object-based storage system (OBS). The storage object can be managed intelligently and the external object access interface is provided in the OSD.The local file system is the core in the software system of OSD. Nowadays distributed storage file systems of Lustre are usually implemented by Ext3. With the increasing workload of OSD, the disadvantage of Ext3 in disk allocation and object lookup would show different degrees of deficiency. The limitation appears more and more outstanding in the management of OSD using Ext3.Aiming at the shortage of Ext3 and combining with the workload characteristics of OSD, this thesis desgins and implements a kind of object-based storage file system-OBSFS on object management for the OSD. First, applying the policy of divided disk space based on size, the system throughput can be improved while the utilization of the disk can be also enhanced; Second, by using the B+ tree and the extent technology to manage free space, different workload of space can use the different allocation strategies to ensure that the objects are continuously stored, which overcomes performance degradation caused by the large object indirect indexing and the disk space can be fast and reasonably allocated; Third, with B+ tree organizing the namespaces, the object metadata can be embedded in the object data block, which achieves that the object being looked-up quickly and object data being accessed directly; Finally, object metadata is stored in the onode that realizes the object metadata and object data to be stored continuously. It helps reducing the overhead of disk seeking.At last, this thesis analyzes the test result of the performance of OBSFS. Through testing, the result shows the performance of OBSFS are both better than Ext3, which is more suitable to be used as the local file system in OSD.