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Virtual Ad Hoc Network (VAN) testbed aims at achieving large scale application testing for ad hoc networks by integrating host virtualization and network simulation. Efficient use of storage space is essential for such testbeds. Storage redundancy resulting from duplicated files and application installations across the virtual machines in a large scale testbed (> a few hundred VMs) can be significantly reduced by using storage sharing techniques. Although Content Addressable Storage (CAS) along with Copyon-write can remove storage redundancy at block-level, it requires hash computation for every write operation that incurs considerable online computation overhead.To address the unique problems where the virtual machines on the testbed would have identical or very similar file system structure, we propose File-level Block Sharing (FBS) that identifies redundant blocks by only comparing the blocks belonging to the files with same or similar filenames across virtual machines. FBS is applicable to both SAN storage systems and cluster file systems. Our proof-of-concept prototype on iSCSI and Linux LVM showed only 1.78% lost in throughput.

Failing network links are usually disabled, and packets are routed around them until the links are repaired. While it is often possible to utilize some of a failing link's capacity, losing what remains of a link's capacity is typically deemed preferable to the erratic effect that unreliable links can have on application-level behavior. We describe a new network function that relies on in-network computing to limit the erratic effect of failing network links, to enable the continued use of those links until they can be repaired. We explore the design space using ns-3, and evaluate our implementation on a physical test-bed that includes programmable switches and reconfigurable hardware. Our current hardware prototype can almost saturate a 10GbE link while using around 10% of our FPGA's resources.