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From: paulo@soprano.chorus.fr (Paulo Amaral)
Newsgroups: comp.arch,comp.protocols.nfs
Subject: Re: Large Files (> 2 GByte) w/NFS
Keywords: NFS FFS Filesystem
Message-ID: <10845@chorus.fr>
Date: 28 May 91 09:02:59 GMT
References: <1991May27.170212.18590@convex.com>
Sender: paulo@chorus.fr
Reply-To: paulo@soprano.chorus.fr (Paulo Amaral)
Organization: Chorus systemes, Saint Quentin en Yvelines, France
Lines: 28

In article <1991May27.170212.18590@convex.com>, hamrick@convex.com (Ed Hamrick) writes:
%% We recently ported the UniTree file migration package to the CONVEX
%% platform, and ran across some NFS issues.  UniTree supports files > 2 GBytes
%% in length, but NFS is limited to files of 2^31-1 bytes (32 bit int field).
%% 
%% We've modified UniTree to allow access to large files (> 2 GBytes) using NFS
%% by always reporting a file length less than 2 GBytes, even when the file is
%% larger than this.  This allows access to the first 2 GBytes of large files,
%% as well as allowing users to use standard file manipulation commands such as
%% ls -l, mv, rm, etc.
%% 
...
%% 
%% I've had the best experiences using NFS block sizes of 512 bytes, as some
%% NFS clients assume this (du utility for instance).  An NFS client should use
%% whatever block size the server reports.
%% 

For a 2Gb file, a 512 byte buffer would mean 4M read operations (RPC requests). Assuming 2 ms for each RPC it would take more than 2 hours to read a whole file whereas with 8kb buffers it would take 8 minutes.
--
        ______
       /     /                          
      /_____/_           ___         Paulo Amaral
     /    /__/ /  / /   /  /         Chorus Systemes 
    /    /  / /__/ /__ /__/          6 avenue Gustave Eiffel 
                                     F-78182, St-Quentin-en-Yvelines Cedex  
Tel: +33 (1) 30 64 82 35               Fax: + 33 (1) 30 57 00 66
E-mail: paulo@chorus.fr              OR paulo%chorus.fr@mcsun.EU.net