Peter Radkov, Li Yin, Pawan Goyal, Prasenjit Sarkarand Prashant Shenoy
tabularccc Dept. of Computer Science& Storage Systems Research & Computer Science Division
University of Massachusetts & IBM Almaden Research Center & University of California
Amherst MA 01003 & San Jose CA 95120 & Berkeley CA 94720
Abstract:
IP-networked storage protocols such as NFS and iSCSI have become increasingly common in today's LAN environments. In this paper, we experimentally compare NFS and iSCSI performance for environments with no data sharing across machines. Our micro- and macro-benchmarking results on the Linux platform show that iSCSI and NFS are comparable for data-intensive workloads, while the former outperforms latter by a factor of two or more for meta-data intensive workloads. We identify aggressive meta-data caching and aggregation of meta-data updates in iSCSI to be the primary reasons for this performance difference and propose enhancements to NFS to overcome these limitations.
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Introduction
Background: NFS and iSCSI
NFS Overview
iSCSI Overview
Differences Between NFS and iSCSI
Setup and Methodology
System Setup
Experimental Methodology
Micro-benchmarking Experiments
Overhead of System Calls
Impact of Meta-data Caching and Update Aggregation
Impact of Directory Depth
Impact of Read and Write Operations
Impact of Sequential and Random I/O
Impact of Network Latency
Macro-benchmarking Experiments
PostMark Results
TPC-C and TPC-H Results
Other Benchmarks
CPU utilization
Discussion of Results
Data-intensive applications
Meta-data intensive applications
Applicability to Other File Protocols
Implications
Potential Enhancements for NFS
Related Work
Concluding Remarks
Bibliography
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