A Case Study on Large-Scale Disk System Concatenating Free Space

The cost of a conventional centralized file server, suitable for use in a learning environment such as a school, is high. However, in PC labs, there are normally several hundreds PCs, with plenty of free disk space. The total size of the unused capacity of the HDDs is almost equivalent to the capacity of a file server. In this paper, we propose constructing a virtual large-scale storage system by concatenating free disk space. We develop the VLSD (virtual large-scale disk) toolkit to aid the construction of such a system. This toolkit is implemented in Java and consists of RAID (redundant arrays of inexpensive/independent disks) and NBDs (network block device). In this paper, we describe how to use VLSD to implement a large-scale storage system.