- </listitem>
- </orderedlist>
- </section>
- <section>
- <title><indexterm><primary>maintenance</primary><secondary>restoring OST config</secondary></indexterm>
-<indexterm><primary>backup</primary><secondary>restoring OST config</secondary></indexterm>
-Restoring OST Configuration Files</title>
- <para>If the original OST is still available, it is best to follow the OST backup and restore procedure given in either <xref linkend="dbdoclet.50438207_71633"/>, or <xref linkend="dbdoclet.50438207_21638"/> and <xref linkend="dbdoclet.50438207_22325"/>.
- </para>
- <para>To replace an OST that was removed from service due to corruption or hardware failure, the file system needs to be formatted for Lustre, and the Lustre configuration should be restored, if available.
-
- </para>
- <para>If the OST configuration files were not backed up, due to the OST file system being completely inaccessible, it is still possible to replace the failed OST with a new one at the same OST index. </para>
- <orderedlist>
- <listitem>
- <para>
- Format the OST file system.
- <screen>oss# mkfs.lustre --ost --index=<replaceable>old_ost_index</replaceable> <replaceable>other_options</replaceable> \
- <replaceable>/dev/new_ost_dev</replaceable></screen>
- </para>
- </listitem>
- <listitem>
- <para>
- Mount the OST filesystem.
+ </listitem>
+ <listitem>
+ <para>If there is not expected to be a replacement for this OST in
+ the near future, permanently deactivate it on all clients and
+ the MDS by running the following command on the MGS:
+ <screen>mgs# lctl conf_param <replaceable>ost_name</replaceable>.osc.active=0</screen></para>
+ <note><para>A deactivated OST still appears in the file system
+ configuration, though a replacement OST can be created using the
+ <literal>mkfs.lustre --replace</literal> option, see
+ <xref linkend="section_restore_ost"/>.
+ </para></note>
+ </listitem>
+ </orderedlist>
+ </listitem>
+ </orderedlist>
+ </section>
+ <section remap="h3" xml:id="section_ydg_pgt_tl">
+ <title><indexterm>
+ <primary>maintenance</primary>
+ <secondary>backing up OST config</secondary>
+ </indexterm>
+ <indexterm>
+ <primary>backup</primary>
+ <secondary>OST config</secondary>
+ </indexterm> Backing Up OST Configuration Files</title>
+ <para>If the OST device is still accessible, then the Lustre
+ configuration files on the OST should be backed up and saved for
+ future use in order to avoid difficulties when a replacement OST is
+ returned to service. These files rarely change, so they can and
+ should be backed up while the OST is functional and accessible. If
+ the deactivated OST is still available to mount (i.e. has not
+ permanently failed or is unmountable due to severe corruption), an
+ effort should be made to preserve these files. </para>
+ <orderedlist>
+ <listitem>
+ <para>Mount the OST file system.
+ <screen>oss# mkdir -p /mnt/ost
+oss# mount -t ldiskfs <replaceable>/dev/ost_device</replaceable> /mnt/ost</screen>
+ </para>
+ </listitem>
+ <listitem>
+ <para>Back up the OST configuration files.
+ <screen>oss# tar cvf <replaceable>ost_name</replaceable>.tar -C /mnt/ost last_rcvd \
+ CONFIGS/ O/0/LAST_ID</screen>
+ </para>
+ </listitem>
+ <listitem>
+ <para> Unmount the OST file system. <screen>oss# umount /mnt/ost</screen>
+ </para>
+ </listitem>
+ </orderedlist>
+ </section>
+ <section xml:id="section_restore_ost">
+ <title><indexterm>
+ <primary>maintenance</primary>
+ <secondary>restoring OST config</secondary>
+ </indexterm>
+ <indexterm>
+ <primary>backup</primary>
+ <secondary>restoring OST config</secondary>
+ </indexterm> Restoring OST Configuration Files</title>
+ <para>If the original OST is still available, it is best to follow the
+ OST backup and restore procedure given in either
+ <xref linkend="dbdoclet.backup_device"/>, or
+ <xref linkend="backup_fs_level"/> and
+ <xref linkend="backup_fs_level.restore"/>.</para>
+ <para>To replace an OST that was removed from service due to corruption
+ or hardware failure, the replacement OST needs to be formatted using
+ <literal>mkfs.lustre</literal>, and the Lustre file system configuration
+ should be restored, if available. Any objects stored on the OST will
+ be permanently lost, and files using the OST should be deleted and/or
+ restored from backup.</para>
+ <para condition="l25">With Lustre 2.5 and later, it is possible to
+ replace an OST to the same index without restoring the configuration
+ files, using the <literal>--replace</literal> option at format time.
+ <screen>oss# mkfs.lustre --ost --reformat --replace --index=<replaceable>old_ost_index</replaceable> \
+ <replaceable>other_options</replaceable> <replaceable>/dev/new_ost_dev</replaceable></screen>
+ The MDS and OSS will negotiate the <literal>LAST_ID</literal> value
+ for the replacement OST.
+ </para>
+ <para>If the OST configuration files were not backed up, due to the
+ OST file system being completely inaccessible, it is still possible to
+ replace the failed OST with a new one at the same OST index. </para>
+ <orderedlist>
+ <listitem>
+ <para>For older versions, format the OST file system without the
+ <literal>--replace</literal> option and restore the saved
+ configuration:
+ <screen>oss# mkfs.lustre --ost --reformat --index=<replaceable>old_ost_index</replaceable> \
+ <replaceable>other_options</replaceable> <replaceable>/dev/new_ost_dev</replaceable></screen>
+ </para>
+ </listitem>
+ <listitem>
+ <para> Mount the OST file system.