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From: sas@pyrps5 (Scott Schoenthal)
Newsgroups: comp.dcom.lans,comp.unix.wizards
Subject: Re: NFS performance: a question
Message-ID: <14163@pyramid.pyramid.com>
Date: 1 Feb 88 16:03:50 GMT
Sender: daemon@pyramid.pyramid.com
Reply-To: sas@pyrps5.pyramid.com (Scott Schoenthal)
Organization: Pyramid Technology Corp., Mountain View, CA
Lines: 19

In article <663@noao.UUCP> brown@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
----
Scott Schoenthal   sas@pyrps5.pyramid.com	Pyramid Technology Corp.