<sect1 id="interop">
 <title>Using Linux NFS with Other OSes</title>
 <para>
   Every operating system, Linux included, has quirks and deviations
   in the behavior of its NFS implementation -- sometimes because
   the protocols are vague, sometimes because they leave gaping
   security holes.  Linux will work properly with all major vendors'
   NFS implementations, as far as we know.  However, there may be
   extra steps involved to make sure the two OSes are communicating
   clearly with one another.  This section details those steps.
 </para>
 <para>
   In general, it is highly ill-advised to attempt to use a Linux
   machine with a kernel before 2.2.18 as an NFS server for non-Linux
   clients.  Implementations with older kernels may work fine as 
   clients; however if you are using one of these kernels and get
   stuck, the first piece of advice we would give is to upgrade
   your kernel and see if the problems go away.  The user-space NFS
   implementations also do not work well with non-Linux clients.
 </para>
 <para>
   Following is a list of known issues for using Linux together with
   major operating systems.
 </para>
 <sect2 id="aix">
  <title>AIX</title>
   <sect3 id="aixserver">
    <title>Linux Clients and AIX Servers</title>
    <para>
      The format for the <filename>/etc/exports</filename> file for our example in <xref linkend="server"> is:
    <programlisting>
  /usr   slave1.foo.com:slave2.foo.com,access=slave1.foo.com:slave2.foo.com
  /home  slave1.foo.com:slave2.foo.com,rw=slave1.foo.com:slave2.foo.com
    </programlisting>
  </para>
 </sect3>
 <sect3 id="aixclients">
   <title>AIX clients and Linux Servers</title>
   <para>
     AIX uses the file <filename>/etc/filesystems</filename> instead of <filename>/etc/fstab</filename>.
     A sample entry, based on the example in <xref linkend="client">, looks like this:
   <programlisting>
/mnt/home:
        dev             = "/home"
        vfs             = nfs
        nodename        = master.foo.com
        mount           = true
        options         = bg,hard,intr,rsize=1024,wsize=1024,vers=2,proto=udp
        account         = false
  </programlisting>
  </para>
  <para>
   <orderedlist numeration="lowerroman">
    <listitem>
     <para>
       Version 4.3.2 of AIX, and possibly earlier versions as well,
       requires that file systems be exported with
       the <userinput>insecure</userinput> option, which 
       causes NFS to listen to requests from 
       insecure ports (i.e., ports above 1024, to which non-root users can 
       bind).  Older versions of AIX do not seem to require this.
     </para>
    </listitem>
    <listitem>
     <para>
       AIX clients will default to mounting version 3 NFS over TCP.
       If your Linux server does not support this, then you may need
       to specify <userinput>vers=2</userinput> and/or 
       <userinput>proto=udp</userinput> in your mount options.
     </para>
    </listitem>
    <listitem>
     <para>
       Using netmasks in <filename>/etc/exports</filename>
       seems to sometimes cause clients
       to lose mounts when another client is reset.  This can be fixed
       by listing out hosts explicitly.
     </para>
    </listitem>
    <listitem>
     <para>
       Apparently automount in AIX 4.3.2 is rather broken.
     </para>
    </listitem>
  </orderedlist>
 </para>
 </sect3>
</sect2>

 <sect2 id="bsd">
  <title>BSD</title>
   <sect3 id="bsdserver">
    <title>BSD servers and Linux clients</title>
     <para>
       BSD kernels tend to work better with larger block sizes.
     </para>
   </sect3>
   <sect3 id="bsdclient">
    <title>Linux servers and BSD clients</title>
     <para>
       Some versions of BSD may make requests to the server from insecure ports,
       in which case you will need to export your volumes with the 
       <userinput>insecure</userinput>
       option.  See the man page for <emphasis>exports(5)</emphasis> 
       for more details.
     </para> 
    </sect3>
  </sect2>
  <sect2 id="tru64">
   <title>Tru64 Unix</title>
   <sect3 id="tru64server">
    <title>Tru64 Unix Servers and Linux Clients</title>
    <para>
      In general, Tru64 Unix servers work quite smoothly with Linux clients.
      The format for the <filename>/etc/exports</filename> file for our example in <xref linkend="server"> is:
   <programlisting>
     
/usr         slave1.foo.com:slave2.foo.com \
     -access=slave1.foo.com:slave2.foo.com \

/home        slave1.foo.com:slave2.foo.com \
         -rw=slave1.foo.com:slave2.foo.com \
       -root=slave1.foo.com:slave2.foo.com 
   </programlisting>
   </para>
<para>
 (The <userinput>root</userinput> option is listed in the last 
 entry for informational purposes only; its use is not recommended
 unless necessary.)
     </para>

   <para>
     Tru64 checks the <filename>/etc/exports</filename> file every time there is a mount request
     so you do not need to run the <command>exportfs</command> command; in fact on many
     versions of Tru64 Unix the command does not exist.
    </para>
   </sect3>
   <sect3 id="tru64client">
    <title>Linux Servers and Tru64 Unix Clients</title>
    <para>
      There are two issues to watch out for here.  First, Tru64 Unix mounts
      using Version 3 NFS by default.  You will see mount errors if your
      Linux server does not support Version 3 NFS.  Second, in Tru64 Unix
      4.x, NFS locking requests are made by 
      <computeroutput>daemon</computeroutput>.  You will therefore
      need to specify the <userinput>insecure_locks</userinput> option on all volumes you export
      to a Tru64 Unix 4.x client; see the <command>exports</command> man pages for details.
    </para>
   </sect3>
  </sect2>
  <sect2 id="hpux">
   <title>HP-UX</title>
    <sect3 id="hpuxserver">
     <title>HP-UX Servers and Linux Clients</title>
     <para>
       A sample <filename>/etc/exports</filename> entry on HP-UX looks like this:
    <programlisting>
/usr -ro,access=slave1.foo.com:slave2.foo.com
/home -rw=slave1.foo.com:slave2.fo.com:root=slave1.foo.com:slave2.foo.com
    </programlisting>
       (The <userinput>root</userinput> option is listed in the last entry for informational
       purposes only; its use is not recommended unless necessary.)
     </para>
  </sect3>
  <sect3 id="hpuxclient">
   <title>Linux Servers and HP-UX Clients</title>
   <para>
     HP-UX diskless clients will require at least a kernel version 2.2.19
     (or patched 2.2.18) for device files to export correctly.  Also, any
     exports to an HP-UX client will need to be exported with the 
     <userinput>insecure_locks</userinput> option.
   </para>
  </sect3>
 </sect2>
 <sect2 id="irix">
  <title>IRIX</title>
  <sect3 id="irixserver">
  <title>IRIX Servers and Linux Clients</title>
  <para>
    A sample <filename>/etc/exports</filename> entry on IRIX looks like this:
  <programlisting>
/usr -ro,access=slave1.foo.com:slave2.foo.com
/home -rw=slave1.foo.com:slave2.fo.com:root=slave1.foo.com:slave2.foo.com
  </programlisting>
    (The <userinput>root</userinput> option is listed in the last entry for informational
    purposes only; its use is not recommended unless necessary.)
  </para>
  <para>
   There are reportedly problems when using the nohide option on
   exports to linux 2.2-based systems.  This problem is fixed in the
   2.4 kernel.  As a workaround, you can export and mount lower-down
   file systems separately.
  </para>
  <para>
   As of Kernel 2.4.17, there continue to be several minor interoperability
   issues that may require a kernel upgrade.  In particular:
  <itemizedlist>
    <listitem>
     <para>
      Make sure that Trond Myklebust's <application>seekdir</application> 
      (or <application>dir</application>) kernel patch is applied.
      The latest version (for 2.4.17) is located at:
     </para>
     <para>
      <ulink url="http://www.fys.uio.no/~trondmy/src/2.4.17/linux-2.4.17-seekdir.dif">
      http://www.fys.uio.no/~trondmy/src/2.4.17/linux-2.4.17-seekdir.dif</ulink>
     </para>
    </listitem>
    <listitem>
     <para>
      IRIX servers do not always use the same 
      <computeroutput>fsid</computeroutput> attribute field across
      reboots, which results in <computeroutput>inode number mismatch</computeroutput> 
      errors on a Linux
      client if the mounted IRIX server reboots. A patch is available from:
     </para>
     <para><ulink url="http://www.geocrawler.com/lists/3/SourceForge/789/0/7777454/">
      http://www.geocrawler.com/lists/3/SourceForge/789/0/7777454/</ulink>
     </para>
    </listitem>
    <listitem>
     <para>
      Linux kernels v2.4.9 and above have problems reading large directories
      (hundreds of files) from exported IRIX XFS file systems that were made
      with <userinput>naming version=1</userinput>.  
      The reason for the problem can be found at:
     </para>
     <para>
      <ulink url="http://www.geocrawler.com/archives/3/789/2001/9/100/6531172/">
       http://www.geocrawler.com/archives/3/789/2001/9/100/6531172/</ulink>
     </para>
     <para>
       The naming version can be found by using (on the IRIX server):
     </para>
     <programlisting>
	xfs_growfs -n mount_point
     </programlisting>
     <para> 
      The workaround is to export these file systems using the 
      <userinput>-32bitclients</userinput>
      option in the <filename>/etc/exports</filename> file.
      The fix is to convert the file system to 'naming version=2'.
      Unfortunately the only way to do this is by a 
      <userinput>backup</userinput>/<userinput>mkfs</userinput>/<userinput>restore</userinput>.
      </para>
      <para>
       <command>mkfs_xfs</command> on IRIX 6.5.14 (and above) 
       creates <userinput>naming version=2</userinput> XFS file
       systems by default. On IRIX 6.5.5 to 6.5.13, use:
      <programlisting>
	mkfs_xfs -n version=2 device
      </programlisting>
      </para>
      <para>
        Versions of IRIX prior to 6.5.5 do not support 
        <userinput>naming version=2</userinput> XFS file systems.
      </para>
     </listitem>
    </itemizedlist>
   </para>


</sect3>
 <sect3 id="irixclient">
 <title>IRIX clients and Linux servers</title>
  <para>
   Irix versions up to 6.5.12 have problems mounting file systems exported
   from Linux boxes - the mount point "gets lost," e.g.,
  <programlisting>
	# mount linux:/disk1 /mnt
	# cd /mnt/xyz/abc
	# pwd
	/xyz/abc
   </programlisting>
   </para>
   <para>
    This is known IRIX bug (SGI bug 815265 - IRIX not liking file handles of
    less than 32 bytes), which is fixed in <application>IRIX 6.5.13</application>.
    If it is not possible 
    to upgrade to <application>IRIX 6.5.13</application>, then the unofficial 
    workaround is to force the Linux <command>nfsd</command> 
    to always use 32 byte file handles. 
   </para>
   <para>
    A number of patches exist - see:
   <itemizedlist>
   <listitem>
   <para>
    <ulink url="http://www.geocrawler.com/archives/3/789/2001/8/50/6371896/">
    http://www.geocrawler.com/archives/3/789/2001/8/50/6371896/</ulink>
   </para>
   </listitem>
   <listitem>
   <para>
   <ulink url="http://oss.sgi.com/projects/xfs/mail_archive/0110/msg00006.html">
    http://oss.sgi.com/projects/xfs/mail_archive/0110/msg00006.html</ulink>
   </para>
   </listitem>
   </itemizedlist>
  </para>
 </sect3>
 </sect2>
 <sect2 id="solaris">
  <title>Solaris</title>
  <sect3 id="solarisserver">
   <title>Solaris Servers</title>
   <para>
     Solaris has a slightly different format on the server end from
     other operating systems.  Instead of 
     <filename>/etc/exports</filename>, the configuration
     file is <filename>/etc/dfs/dfstab</filename>.  Entries are of 
     the form of a <command>share</command> command, where the syntax
     for the example in <xref linkend="server"> would look like
   <programlisting>
share -o rw=slave1,slave2 -d "Master Usr" /usr
   </programlisting>
     and instead of running <command>exportfs</command> after editing, you run <command>shareall</command>.
   </para>
   <para>
     Solaris servers are especially sensitive to packet size. If you
     are using a Linux client with a Solaris server, be sure to set
     <userinput>rsize</userinput> and <userinput>wsize</userinput>
     to 32768 at mount time.
   </para>
   <para>
     Finally, there is an issue with root squashing on Solaris: root gets
     mapped to the user <computeroutput>noone</computeroutput>, which 
     is not the same as the user <computeroutput>nobody</computeroutput>.
     If you are having trouble with file permissions as root on the client
     machine, be sure to check that the mapping works as you expect.
   </para>
  </sect3>
  <sect3 id="solarisclient">
   <title>Solaris Clients</title>
   <para>
     Solaris clients will regularly produce the following message:
    </para>
  <screen>
svc: unknown program 100227 (me 100003)
  </screen>
  <para>
    This happens because Solaris clients, when they mount, try to obtain
    ACL information - which Linux obviously does not have. The messages
    can safely be ignored. 
  </para>
  <para>
    There are two known issues with diskless Solaris clients: First, a kernel
    version of at least 2.2.19 is needed to get <filename>/dev/null</filename> to export 
    correctly.  Second, the packet size may need to be set extremely
    small (i.e., 1024) on diskless sparc clients because the clients
    do not know how to assemble packets in reverse order.  This can be
    done from <filename>/etc/bootparams</filename> on the clients.
   </para>
  </sect3>
 </sect2>
 <sect2 id="sunos">
  <title>SunOS</title>
  <para>
    SunOS only has NFS Version 2 over UDP.
  </para>
  <sect3 id="sunosserver">
   <title>SunOS Servers</title>
   <para>
     On the server end, SunOS uses the most traditional format for its 
     <filename>/etc/exports</filename> file. The example in <xref linkend="server"> would look like:
   <programlisting>
/usr    -access=slave1.foo.com,slave2.foo.com
/home   -rw=slave1.foo.com,slave2.foo.com, root=slave1.foo.com,slave2.foo.com
   </programlisting>
  </para>
  <para>
   Again, the <userinput>root</userinput> option is listed for informational
   purposes and is not recommended unless necessary.
  </para>
  </sect3>
  <sect3 id="sunosclient">
  <title>SunOS Clients</title>
  <para>
    Be advised that SunOS makes all NFS locking requests 
    as <computeroutput>daemon</computeroutput>, and 
    therefore you will need to add the <userinput>insecure_locks</userinput> option to any 
    volumes you export to a SunOS machine.  See the <command>exports</command> man page
    for details.
  </para>
 </sect3>
</sect2>
</sect1>





