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Published byKaren Webb Modified over 9 years ago
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Direct Access File System (DAFS): Duke University Demo Source-release reference implementation of DAFS Broader research goal: Enabling efficient and transparently scalable Internet-based storage and content services Example applications built on TPIE framework –Merge –TerraFlow – GIS DAFS vs. NFS Participants: Jeff Chase, Richard Kisley, Andrew Gallatin, Rajiv Wickremesinghe, Darrell Anderson, Ken Yocum. Collaborators: Margo Seltzer, Norm Hutchinson. Funding provided by Network Appliance and by the National Science Foundation under grant EIA-9870724 (ESS), with infrastructure support from EIA-9972879 (RI).
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DAFS Demo Testbed DAFS / NFS Client 256MB SDRAM DAFS / NFS Server 512MB SDRAM cLAN GigEther 86 MB/s Testbed allows direct comparison of DAFS and NFS applications
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User Space OS Kernel PCI Bus NIC TPIE: One Application–Two File Systems DMA User Applications TPIE Library cLAN VIA Adapter DAFS Client cLAN VIA cLAN VIPL Library cLAN Device Driver DAFS Client Library copyin/out DMA User Applications TPIE Library VFS/VM Buffercache NFS TCP/IP Stack Ethernet Device Driver Alteon Gigabit Ethernet Adapter NFS Client Ethernet
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Benefits of DAFS Low I/O overhead –Copy-avoidance with RDMA –Improves application performance up to 2x depending on the I/O demands of the application –Benefits may be much higher since the NFS in our experiments is highly optimized User-level networking –Enabled by the Emulex/Giganet clan VI network –Reduced protocol overhead on the host –Reduced context switching on the host
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TPIE Merge Application Key component of external sort algorithm –Basic primitive of many external memory applications Sequential I/O: reads and writes Merge parameters control compute-I/O ratio –Merge order increases complexity of merge computation –Record density (records / MB) increases the number of merge computations that must be done between I/O’s
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