Performance Analysis of Network File Systems

In a local area network, the efficiency of the network file system is a key perfor-mance issue. This paper compares several different classes of network file systems with respect to number of file transfers and auxiliary messages processed by each node. The file system classes compared are: (a) remote file access, (b) polling (each node may create a read-only replicate of a file, but must poll the primary copy to deter-mine whether it is up-to-date), (c) broadcast staling (each update broadcasts a mes-sage to mark replicates as stale), (d) multicast staling (each update sends an outdating message to the sites with replicates). The results show that, under realistic assumptions, both polling and staling require 30-50 % fewer file transfers than remote file access, while simultaneously increasing reliability because of replication. However, polling and staling generate auxiliary messages. Broadcast staling performs poorly in large nets because every node must process an auxiliary message for every update in the net. Polling generates numerous useless messages if the read ratio is high. Multicast staling performs best. It gen. erates one half to one fiith of the auxiliary messages produced by polling. Further-more, the load on each workstation is small and independent of the network size