关键词: 透明计算, 虚拟磁盘镜像, 写时重定向（ROW）, 位图索引

Abstract: The existing virtual disk image storage models are not suitable for the data sharing of large number of users in transparent computing platform due to the excessive redundant data. To solve the shortcoming, this paper proposes a tree virtual disk storage model (TVDSM) based on ROW (redirect-on-write). In the TVDSM, the virtual disk data resources are divided into multiple layers according to sharing degree, and different end-users share system resources and application software resources which are located in the upper layers, the model only stores self-rewritten data, thus greatly reduces the redundant data in virtual disk storage system. Then, this paper designs and implements a linking virtual disk storage structure based on bitmap index technology. The structure can not only well support the virtual disk storage model presented in the paper, but also support ROW and query location operation to realize separately with different granularity, which enables the system to obtain higher query efficiency in a smaller sharing granularity.

Key words: transparent computing, virtual disk image, redirect-on-write (ROW), bitmap