+ <section xml:id="lustremaint.clear_conf" condition="l2B">
+ <title><indexterm>
+ <primary>maintenance</primary>
+ <secondary>Clearing a config</secondary>
+ </indexterm> Clearing configuration</title>
+ <para>
+ This command runs on MGS node having the MGS device mounted with
+ <literal>-o nosvc.</literal> It cleans up configuration files
+ stored in the CONFIGS/ directory of any records marked SKIP.
+ If the device name is given, then the specific logs for that
+ filesystem (e.g. testfs-MDT0000) are processed. Otherwise, if a
+ filesystem name is given then all configuration files are cleared.
+ The previous configuration log is backed up on the MGS disk with
+ the suffix 'config.timestamp.bak'. Eg: Lustre-MDT0000-1476454535.bak.
+ </para>
+ <para> To clear a configuration:</para>
+ <orderedlist>
+ <listitem>
+ <para>Shut down the file system in this order:</para>
+ <orderedlist>
+ <listitem>
+ <para>Unmount the clients.</para>
+ </listitem>
+ <listitem>
+ <para>Unmount the MDT.</para>
+ </listitem>
+ <listitem>
+ <para>Unmount all OSTs.</para>
+ </listitem>
+ </orderedlist>
+ </listitem>
+ <listitem>
+ <para>
+ If the MGS and MDS share a partition, start the MGS only
+ using "nosvc" option.
+ </para>
+ <screen>mount -t lustre <replaceable>MDT partition</replaceable> -o nosvc <replaceable>mount_point</replaceable></screen>
+ </listitem>
+ <listitem>
+ <para>Run the <literal>clear_conf</literal> command on the MGS:
+ </para>
+ <screen>lctl clear_conf <replaceable>config</replaceable></screen>
+ <para>
+ Example: To clear the configuration for
+ <literal>MDT0000</literal> on a filesystem named
+ <literal>testfs</literal>
+ </para>
+ <screen>mgs# lctl clear_conf testfs-MDT0000</screen>
+ </listitem>
+ </orderedlist>
+ </section>
+ <section xml:id="lustremaint.adding_new_mdt" condition='l24'>
+ <title><indexterm>
+ <primary>maintenance</primary>
+ <secondary>adding an MDT</secondary>
+ </indexterm>Adding a New MDT to a Lustre File System</title>
+ <para>Additional MDTs can be added using the DNE feature to serve one
+ or more remote sub-directories within a filesystem, in order to
+ increase the total number of files that can be created in the
+ filesystem, to increase aggregate metadata performance, or to isolate
+ user or application workloads from other users of the filesystem. It
+ is possible to have multiple remote sub-directories reference the
+ same MDT. However, the root directory will always be located on
+ MDT0. To add a new MDT into the file system:</para>