Adapting Storage Protocol Stack Using Custom File Metadata to Commodity Linux Servers

It has been a challenge for storage vendors to adapt their proprietary protocol stacks to commodity servers. Despite large development effort, many proprietary protocol stacks are available only on the specialized storage appliances because of the dependency on the hardware or software modules. Most of these protocol stacks use original filesystems to store custom file metadata to be compliant with the protocol specifications. In this paper, we propose the protocol metadata module (PMM) which enables the capability of the custom file metadata on Linux filesystems. PMM allows the protocol stacks using the custom file metadata to offer the protocol functions in a protocol compliant manner on Linux servers. We applied PMM to our proprietary protocol stack to confirm that PMM can achieve higher protocol function coverage and reasonable performance. Our evaluations show that PMM increases the protocol function coverage from 75.0% to 96.7% on Linux servers while suppressing the access performance degradation to at most 8% in the typical file server workloads.