Research Of File-Backed Xen Virtual Disk

With the development of the internet, the requirement of software compatibility and migration increased. It comes with a period of virtual machine technology, which becomes one of the fastest developed technology within the computer science field. According to the differences of virtual machine monitor framework or whether to modify guest operating system, we can classify virtualization technology as para-virtualization and full-virtualization. At first, Xen was a para-virtualized machine developed by Cambridge research group.I/O performance is always a weak aspect of the whole virtualization technology. In this thesis, we research deeply on disk virtualization of Xen, amply analyse the architecture and implementation theory of virtual disk access, discuss the effect of I/O performance through different access module and different virtual disk format. At last, we focus on the Qcow format virtual disk, add simulated tlb, cache, readahead technology on it. Via these measures, we translate original direct disk access into memory access and improve the virtual disk I/O performance.Finally, with the experiment analysis, we validate the feasibility of the improved virtual disk module and find out that the performance of the modified virtual model is excellent. Also this kind of improvement measure can also be implemented in other virtual disk format and other I/O virtualization technique. So the method has strong use value and wide application scale.