NFS performance: a question

[Scott Schoenthal]

In article <663 at noao.UUCP> brown at noao.arizona.edu (Mike Brown) writes:
>
>Why is the transfer rate when a process writes to a remote NFS file 3-4 times
>smaller than the transfer rate when reading a remote NFS file?

Due to the stateless nature of NFS, all write requests received by a
server must be written synchronously to the disk before they can be
acknowledged to the client.  If this was not true, the following could happen:

Client A sends a write request (block 'n') to Server B.  Server B
acknowledges the write but does not write the block.  Server B crashes.
Server B then comes back up.  Client A will then send block 'n+1'
thinking that 'n' has been written out.

In a UNIX NFS server implmenetation, the inode and block maps must
also be updated during each synchronous block write.

sas
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Scott Schoenthal   sas at pyrps5.pyramid.com	Pyramid Technology Corp.