Effect of biods on NFS Performance

About biods

• Biods (block I/O daemons) are used by NFS to allow more outstanding RPC requests per host
• Ecah biod is a seperate process
• The number of biods is a indication of the amount of concurrency

• Red lines represent the maximum and minimum of the sample set

Adding biods does not improve NFS performance

• Empirically, there is an upper bound on throughput around 40 Mb/sec
• CPU measurements show that 2 biods cause a CPU utilization of 90%+ on a client
• It appears that the cost of a seperate process per biod outweighs the increase in concurrency

Compare with AFS performance varying the number of afsds.

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Last modified August 2, 1995.