Storage Deduplication and Management for Application Testing over a Virtual Network Testbed

With the virtual machine technologies, Virtual Ad hoc Network (VAN) testbed was designed to evaluate functional correctness and communication performance of Mobile Ad hoc Network (MANET) applications. When VAN is used for large-scale testing that requires hundreds of virtual machines, storage redundancy becomes an issue. Although Content Addressable Storage (CAS) techniques were designed to address the storage redundancy issue, it incurred online hash computation overhead for every write access to disk blocks, which affects testing accuracy. We present File-level Block Sharing (FBS) that achieves the same functionality of CAS while removing the online computation overhead. By getting file-to-block mappings through read-only mounting, FBS only needs to handle the blocks belonging to newly-installed files offline and thus incurs little online overhead. Our prototype showed no online overhead statistically and low offline overhead. The prototype was developed and its overhead with respect to block-level storage deduplication was analyzed under both Ext2/3/4 and NTFS file systems.