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181 lines
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181 lines
13 KiB
XML
<?xml version="1.0" encoding="utf-8"?>
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<appendix id="HDRWQ80"><title>Using the NFS/AFS Translator</title>
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<para>
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<indexterm><primary>NFS</primary><secondary>accessing AFS from client</secondary></indexterm>
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<indexterm><primary>NFS/AFS Translator</primary></indexterm>
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<indexterm><primary>AFS</primary><secondary>accessing from NFS client machine</secondary></indexterm>
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<indexterm><primary>access to AFS filespace</primary><secondary>from NFS client machines</secondary></indexterm>
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Some
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cells use the Network File System (NFS) in addition to AFS. If you work on an NFS client machine, your system
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administrator can configure it to access the AFS filespace through a program called the <emphasis>NFS/AFS
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Translator</emphasis><superscript>TM</superscript>. If you have an AFS account, you can access AFS as an
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authenticated user while working on your NFS client machine. Otherwise, you access AFS as the
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<emphasis role="bold">anonymous</emphasis> user.</para>
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<note>
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<para>Acceptable NFS/AFS Translator performance requires that NFS is functioning correctly.</para>
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</note>
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<sect1 id="HDRWQ81"><title>Requirements for Using the NFS/AFS Translator</title>
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<para>
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<indexterm><primary>NFS</primary><secondary>issuing AFS commands on NFS client machine</secondary></indexterm>
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<indexterm><primary>commands</primary><secondary>AFS, issuing on NFS client machine</secondary></indexterm>
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For you to use the NFS/AFS Translator, your system
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administrator must configure the following types of machines as indicated:</para>
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<itemizedlist>
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<listitem><para>An <emphasis>NFS/AFS translator machine</emphasis> is an AFS client machine that also acts as an
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NFS server machine. Its Cache Manager acts as the surrogate Cache Manager for your NFS client machine. Ask your
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system administrator which translator machines you can use.</para></listitem>
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<listitem><para>Your NFS client machine must have an NFS mount to a translator machine. Most often, your system
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administrator mounts the translator machine's <emphasis role="bold">/afs</emphasis> directory and names the mount
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<emphasis role="bold">/afs</emphasis> as well. This enables you to access the entire AFS filespace using standard
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AFS pathnames. It is also possible to create mounts directly to subdirectories of
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<emphasis role="bold">/afs</emphasis>, and to give NFS mounts different names on the NFS client
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machine.</para></listitem>
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</itemizedlist>
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<para>Your access to AFS is much more extensive if you have an AFS user account. If you do not, the AFS servers
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recognize you as the <emphasis role="bold">anonymous</emphasis> user and only grant you the access available to
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members of the <emphasis role="bold">system:anyuser</emphasis> group.</para>
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<para>If your NFS client machine uses an operating system that AFS supports, your system administrator can
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configure it to enable you to issue many AFS commands on the machine. Ask him or her about the configuration and
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which commands you can issue.</para>
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</sect1><sect1 id="Header_160"><title>Accessing AFS via the Translator</title>
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<indexterm><primary>authentication</primary><secondary>to AFS on NFS client machines</secondary></indexterm>
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<para>If you do not have an AFS account or choose not to access AFS as an authenticated user, then all you do to
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access AFS is provide the pathname of the relevant file. Its ACL must grant the necessary permissions to the
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<emphasis role="bold">system:anyuser</emphasis> group.</para>
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<para>If you have an AFS account and want to access AFS as an authenticated user, the best method depends on
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whether your NFS machine is a supported type. If it is, use the instructions in <link linkend="HDRWQ82">To
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Authenticate on a Supported Operating System</link>. If it is not a supported type, use the instructions in
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<link linkend="HDRWQ83">To Authenticate on an Unsupported Operating System</link>.</para>
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<sect2 id="HDRWQ82"><title>To Authenticate on a Supported Operating System</title>
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<orderedlist>
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<listitem><para>Log into the NFS client machine using your NFS username.</para></listitem>
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<listitem><para>
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Issue the <emphasis role="bold">klog</emphasis> command. For complete instructions, see
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<link linkend="HDRWQ29">To Authenticate with AFS</link>.
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<programlisting>
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% <emphasis role="bold">klog -setpag</emphasis>
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</programlisting>
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</para></listitem>
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</orderedlist>
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</sect2><sect2 id="HDRWQ83"><title>To Authenticate on an Unsupported Operating System</title>
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<orderedlist>
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<listitem><para>Log onto the NFS client machine using your NFS username.</para></listitem>
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<listitem><para><anchor id="LINFS-TELNET" />Establish a connection to the NFS/AFS translator machine you are
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using (for example, using the <emphasis role="bold">telnet</emphasis> utility) and log onto it using your AFS
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username (which is normally the same as your NFS username).</para></listitem>
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<listitem><para>
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If the NFS/AFS translator machine uses an AFS-modified login utility, then you obtained AFS tokens in Step
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<link linkend="LINFS-TELNET">2</link>. To check, issue the <emphasis role="bold">tokens</emphasis> command,
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which is described fully in <link linkend="HDRWQ30">To Display Your Tokens</link>.
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<programlisting>
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% <emphasis role="bold">tokens</emphasis>
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</programlisting>
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If you do not have tokens, issue the <emphasis role="bold">klog</emphasis> command, which is described fully in
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<link linkend="HDRWQ29">To Authenticate with AFS</link>.
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<programlisting>
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% <emphasis role="bold">klog -setpag</emphasis>
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</programlisting>
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</para></listitem>
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<listitem><para>
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<anchor id="LINFS-KNFS" />Issue the <emphasis role="bold">knfs</emphasis> command to associate your AFS tokens
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with your UNIX UID on the NFS client machine where you are working. This enables the Cache Manager on the
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translator machine to use the tokens properly when you access AFS from the NFS client machine.
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</para><para>If your NFS client machine is a system type for which AFS defines a system name, it can make sense
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to add the <emphasis role="bold">-sysname</emphasis> argument. This argument helps the Cache Manager access
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binaries specific to your NFS client machine, if your system administrator has used the
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<emphasis>@sys</emphasis> variable in pathnames. Ask your system administrator if this argument is useful for
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you.
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<indexterm><primary>knfs command</primary></indexterm>
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<indexterm><primary>commands</primary><secondary>knfs</secondary></indexterm>
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</para>
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<programlisting>
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% <emphasis role="bold">knfs</emphasis> <<replaceable>host name</replaceable>> [<<replaceable>user ID (decimal)</replaceable>>] \
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[<emphasis role="bold">-sysname</emphasis> <<replaceable>host's '@sys' value</replaceable>>]
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</programlisting>
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<para>where</para>
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<variablelist>
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<varlistentry><term><emphasis role="bold"><replaceable>host name</replaceable></emphasis></term>
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<listitem><para>Specifies the fully-qualified hostname of your NFS client machine (such as
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<emphasis role="bold">nfs52.abc.com</emphasis>).</para></listitem></varlistentry>
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<varlistentry><term><emphasis role="bold"><replaceable>user ID</replaceable></emphasis></term>
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<listitem><para>Specifies your UNIX UID or equivalent (not your username) on the NFS client machine. If your
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system administrator has followed the conventional practice, then your UNIX and AFS UIDs are the same. If you
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do not know your local UID on the NFS machine, ask your system administrator for assistance. Your system
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administrator can also explain the issues you need to be aware of if your two UIDs do not match, or if you
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omit this argument.</para></listitem></varlistentry>
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<varlistentry><term><emphasis role="bold">-sysname</emphasis></term>
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<listitem><para>Specifies your NFS client machine's system type name.</para></listitem></varlistentry>
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</variablelist>
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</listitem>
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<listitem><para><anchor id="LINFS-LOGOUT" />(<emphasis role="bold">Optional</emphasis>) Log out from the
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translator machine, but do not unauthenticate.</para></listitem>
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<listitem><para>Work on the NFS client machine, accessing AFS as necessary.</para></listitem>
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<listitem><para>
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When you are finished accessing AFS, issue the <emphasis role="bold">knfs</emphasis> command on the translator
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machine again. Provide the same <replaceable>host name</replaceable> and <replaceable>user ID</replaceable>
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arguments as in Step <link linkend="LINFS-KNFS">4</link>, and add the <emphasis role="bold">-unlog</emphasis>
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flag to destroy your tokens. If you logged out from the translator machine in Step
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<link linkend="LINFS-LOGOUT">5</link>, then you must first reestablish a connection to the translator machine
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as in Step <link linkend="LINFS-TELNET">2</link>.
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<programlisting>
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% <emphasis role="bold">knfs</emphasis> <<replaceable>host name</replaceable>> [<<replaceable>user ID (decimal)</replaceable>>] <emphasis role="bold">-unlog</emphasis>
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</programlisting>
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</para></listitem>
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</orderedlist>
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</sect2></sect1><sect1 id="HDRWQ84"><title>Troubleshooting the NFS/AFS Translator</title>
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<para>Acceptable performance by the NFS/AFS translator depends for the most part on NFS. Sometimes, problems that
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appear to be AFS file server outages, broken connections, or inaccessible files are actually caused by NFS
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outages.</para>
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<para>This section describes some common problems and their possible causes. If other problems arise, contact your
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system administrator, who can ask the AFS Product Support group for assistance if necessary.</para>
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<note>
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<para>To avoid degrading AFS performance, the Cache Manager on the translator machine does not immediately
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send changes made on NFS client machines to the File Server. Instead, it checks every 60 seconds for such
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changes and sends them then. It can take longer for changes made on an NFS client machine to be saved than for
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changes made on an AFS client machine. The save operation must complete before the changes are visible on NFS
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client machines that are using a different translator machine or on AFS client machines.</para>
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</note>
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<sect2 id="HDRWQ85"><title>Your NFS Client Machine is Frozen</title>
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<para>If your system administrator has used the recommended options when creating an NFS mount to an NFS/AFS
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translator machine, then the mount is both <emphasis>hard</emphasis> and <emphasis>interruptible</emphasis>:</para>
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<itemizedlist>
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<listitem><para>A hard mount means that the NFS client retries its requests if it does not receive a response
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within the expected time frame. This is useful because requests have to pass through both the NFS and AFS client
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software, which can sometimes take longer than the NFS client expects. However, it means that if the NFS/AFS
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translator machine actually becomes inaccessible, your NFS client machine can become inoperative
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(<emphasis>freeze</emphasis> or <emphasis>hang</emphasis>).</para></listitem>
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<listitem><para>If the NFS mount is interruptible, then in the case of an NFS/AFS translator machine outage you
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can press <<emphasis role="bold">Ctrl-c</emphasis>> or another interrupt signal to halt the NFS client's
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repeated attempts to access AFS. You can then continue to work locally, or can NFS-mount another translator
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machine. If the NFS mount is not interruptible, you must actually remove the mount to the inaccessible translator
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machine.</para></listitem>
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</itemizedlist>
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</sect2><sect2 id="Header_165"><title>NFS/AFS Translator Reboots</title>
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<para>If you have authenticated to AFS and your translator machine reboots, you must issue the
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<emphasis role="bold">klog</emphasis> command (and <emphasis role="bold">knfs</emphasis> command, if appropriate)
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to reauthenticate. If you used the <emphasis role="bold">knfs</emphasis> command's
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<emphasis role="bold">-sysname</emphasis> argument to define your NFS client machine's system name, use it
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again.</para>
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</sect2><sect2 id="Header_166"><title>System Error Messages</title>
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<para>This section explains possible meanings for NFS error messages you receive while accessing AFS
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filespace.</para>
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<para><computeroutput>stale NFS client</computeroutput></para>
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<para><computeroutput>Getpwd: can't read</computeroutput></para>
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<para>Both messages possibly means that your translator machine was rebooted and cannot determine the pathname to
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the current working directory. To reestablish the path, change directory and specify the complete pathname starting
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with <emphasis role="bold">/afs</emphasis>.</para>
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<para><computeroutput>NFS server <replaceable>translator_machine</replaceable> is not responding still
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trying</computeroutput>.</para>
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<para>The NFS client is not getting a response from the NFS/AFS translator machine. If the NFS mount to the
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translator machine is a hard mount, your NFS client continues retrying the request until it gets a response (see
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<link linkend="HDRWQ85">Your NFS Client Machine is Frozen</link>). If the NFS mount to the translator machine is a
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soft mount, the NFS client stops retrying after a certain number of attempts (three by default).</para>
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</sect2></sect1></appendix>
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