Evaluation of I/O technologies on a flash-based I/O sub-system for HPC

To meet the growing demand for high performance computing systems that are capable of processing large datasets, the San Diego Supercomputer Center is deploying Gordon. This system was specifically designed for data intensive workloads and uses flash memory to fill the large latency gap in the memory hierarchy between DRAM and hard disk. In preparation for the deployment of Gordon, we evaluated the performance of multiple remote storage technologies and file systems for use with the flash memory. We find that OCFS and XFS are both superior to PVFS at delivering fast random access to flash. In addition, our tests indicate that the Linux SCSI target framework (TGT) can export flash storage devices with minimal overhead and achieve a large fraction of the theoretical peak I/O performance. Despite the difficulties in fairly comparing I/O solutions due to the many differences in file systems and service implementations, we conclude that OCFS on TGT is a viable option for our system as it provides both excellent performance and a user-friendly shared file system interface. In those instances where a parallel file system is not required, XFS on TGT is a better alternative.