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+<?xml version="1.0" encoding="UTF-8"?>
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+<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
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+"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd" [
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+<!ENTITY mdash "—" >
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+]>
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+
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+ <chapter id="kea-lfc">
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+ <title>The LFC process</title>
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+
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+ <section id="kea-lfc-overview">
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+ <title>Overview</title>
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+ <para><command>kea-lfc</command> is a service process that removes
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+ redundant infomation from the files used to provide persistent storage
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+ for the memfile data base backend. This service is written to run as a
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+ stand alone process.
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+ </para>
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+ <para>While <command>kea-lfc</command> can be started externally it should
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+ be started by the Kea DHCP servers.
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+ </para>
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+ <para>The process operates on a set of files, using them for input and output
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+ of the lease entries and to indicate where it is in the process in case of an
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+ interruption. Currently the caller must supply names for all of the files, in
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+ the future this requirement may be relaxed with the process getting the names
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+ from either the config file or from defaults.
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+ </para>
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+ </section>
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+
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+ <section id="kea-lfc-usage">
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+ <title>Command Line Options</title>
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+ <para><command>kea-lfc</command> is run as follows:
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+<screen>
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+kea-lfc [-4 | -6] -c config-file -p pid-file -x previous-file -i copy-file -o output-file -f finish-file
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+</screen>
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+ </para>
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+
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+ <para>The argument <command>-4</command> or <command>-6</command> selects the protocol
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+ version of the lease files.
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+ </para>
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+
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+ <para>The <command>-c</command> argument specifies the configuration file. This is
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+ required, but not currently used by the process.
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+ </para>
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+
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+ <para>The <command>-p</command> argument specifies the PID file. When the
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+ <command>kea-lfc</command> process starts it attempts to determine if another
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+ instance of the process is already running by examining the pid file. If one
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+ is running it aborts the new process. If one isn't running it writes its
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+ pid into the pid file.
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+ </para>
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+
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+ <para>The other filenames specify where the <command>kea-lfc</command> process
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+ should look for input, write its output and use for bookkeeping.
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+
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+ <itemizedlist>
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+ <listitem><simpara>
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+ <command>previous</command> —
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+ When <command>kea-lfc</command> starts this
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+ is the result of any previous run of <command>kea-lfc</command>.
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+ When <command>kea-lfc</command> finishes it is the result of this run.
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+ If <command>kea-lfc</command> is interrupted before compelting
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+ this file may not exist.
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+ </simpara></listitem>
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+
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+ <listitem><simpara>
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+ <command>input</command> —
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+ Before the DHCP server invokes <command>kea-lfc</command> it will
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+ copy the current lease file here and then call <command>kea-lfc</command>
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+ with this file.
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+ </simpara></listitem>
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+
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+ <listitem><simpara>
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+ <command>output</command> —
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+ The temporary file <command>kea-lfc</command> should use to write the leases.
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+ Upon completion of writing this this file it will be moved to the finish file
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+ (see below).
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+ </simpara></listitem>
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+
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+ <listitem><simpara>
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+ <command>finish</command> —
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+ Another temporary file <command>kea-lfc</command> uses for bookkeeping. When
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+ <command>kea-lfc</command> completes writing the outputfile it moves it to this
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+ file name. After <command>kea-lfc</command> finishes deleting the other files
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+ (previous and input) it moves this file to previous lease file. By moving the
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+ files in this fashion the <command>kea-lfc</command> and the DHCP server
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+ processes can determine the correct file to use even if one of the
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+ processes was interrupted before completing its task.
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+ </simpara></listitem>
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+
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+ </itemizedlist>
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+ </para>
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+
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+ <para>There are several additional arguments mostly for debugging purposes.
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+ <command>-d</command> Sets the logging level to debug. <command>-v</command> and
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+ <command>-V</command> print out version stamps with <command>-V</command> providing
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+ a longer form. <command>-h</command> prints out the usage string.
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+ </para>
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+
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+ </section>
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+ </chapter>
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Shawn Routhier