- <note><para>
- <emphasis role="bold">Prior to Lustre software release 2.3</emphasis>, the
- only successful way to perform an MDT backup and restore was to do a
- device-level backup as described in
- <xref linkend="dbdoclet.backup_device" />. The ability to do MDT
- file-level backups is not available for Lustre software release 2.0
- through 2.2, because restoration of the Object Index (OI) file does not
- return the MDT to a functioning state.</para>
- <para><emphasis role="bold">Since Lustre software release 2.3</emphasis>,
- Object Index files are automatically rebuilt at first mount after a
- restore is detected (see
- <link xl:href="http://jira.whamcloud.com/browse/LU-957">LU-957</link>),
- so file-level MDT restore is supported.</para></note>
+ <note>
+ <para>Since Lustre stores internal metadata that maps FIDs to local
+ inode numbers via the Object Index file, they need to be rebuilt at
+ first mount after a restore is detected so that file-level MDT backup
+ and restore is supported. The OI Scrub rebuilds these automatically
+ at first mount after a restore is detected, which may affect MDT
+ performance after mount until the rebuild is completed. Progress can
+ be monitored via <literal>lctl get_param osd-*.*.oi_scrub</literal>
+ on the MDS or OSS node where the target filesystem was restored.
+ </para>
+ </note>