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    DateThu, 22 Nov 2001 09:52:51 +0100
    FromSamuel Maftoul <>
    SubjectNFS problem
    Hello,
            I have a QFS filesystem on a solaris 8 which is exported via
    NFS:
    qfs1                 2848604160 3996672 2844607488     1%
    /data/id19/inhouse
    
    ([3] % uname -a 
    SunOS azure 5.8 Generic_108528-09 sun4u sparc SUNW,Ultra-4 )
    
    The QFS have an option on it's directories: you can change the attributes
    on a directory with setfa (set file atrributes) to direct IO or page
    cache.
    Here is the concerned excerpt of the QFS setfa manpage:
    "
         -D   Specifies the direct I/O attribute be permanently set
              for this file.  This means data is transferred directly
              between the user's buffer and disk.  This attribute
              should only be set for large block aligned sequential
              I/O.  The default I/O mode is buffered (uses the page
              cache).  Directio will not be used if the file is
              currently memory mapped.  See man directio(3C) for
              Solaris 2.6 and above for more details, however the
              SAM-FS directio attribute is permanent.
    "
    With this option we have strange performences:
    >From a solaris client to this solaris server we have approximatively
    40MB/s, with a linux client >1MB/s. Without directio mode we have
    approximatively 20MB/s on a linux and 20MB/s on a solaris
    ( I have tested on several solaris clients, several linux client with
    gigabit ethernet links and without (for having 20MB/s) ).
    
    I thought that NFS's underlying FS do not have any effect on NFS
    performances, and that the client is not aware of the ("local") remote
    FS. 
    Am I wrong ? 
    Does anybody have an idea to fix the problem ? 
    Is it a bug in NFS's implementation of linux kernel ?
    
    Thanks in advance
            Sam
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