On providing an efficient and reliable virtual block storage service

[摘要] ENGLISH ABSTRACT:This thesis describes the design and implementation of a data storage service. Manyclients can be served simultaneously in an environment where processes execute ondifferent physical machines and communicate via message passing primitives. Theservice is provided by two separate servers: one that functions at the disk block leveland another that maintains files.A prototype system was developed first in the form of a simple file store. The prototypeserved two purposes: (1) it extended the single-user Oberon system to create a multiusersystem suitable to support group work in laboratories, and (2) it provided a systemthat could be measured to obtain useful data to design the final system. Clients accessthe service from Oberon workstations. The Oberon file system (known as the Ceres filesystem) normally stores files on a local disk. This system was modified to store files ona remote Unix machine. Heavily used files are cached to improve the efficiency of thesystem.In the final version of the system disk blocks are cached, not entire files. In this waythe disks used to store the data are unified and presented as a separate virtual blockservice to be used by file systems running on client workstations. The virtual blockserver runs on a separate machine and is accessed via a network. The simplicity of theblock server is appealing and should in itself improve reliability. The main concern isefficiency and the goal of the project was to determine whether such a design can bemade efficient enough to serve its purpose.

[发布机构] Stellenbosch University