On 2014/10/29, 9:48 AM, "DEGREMONT Aurelien" <aurelien.degremont(a)cea.fr&gt; wrote: Multiple OI files are created for new filesystems by default. You can also cause OI Scrub to rebuild the OI file if the current OI file is corrupted or missing. Before changing anything, I'd recommend making a "dd" backup of the whole MDT to a separate device, just in case of problems, and because having a backup of the MDT is always a good thing. Since a block-level backup is doing large streaming reads and doesn't traverse the filesystem namespace, this can run quite quickly, and can use inexpensive SATA disk(s) for storage. You can mount the MDT locally as type ldiskfs, rename the oi.16 file, then mount the MDT as type lustre and OI scrub should begin automatically at mount (see "lctl get_param . The OI Scrub speed was tested at about 100k files/sec, so that would take at least 15 minutes to complete. It is possible for clients to have some amount of access to the filesystem while scrub is running. While this is better to have some partial access than none at all, not all operations work (lookup or revalidate by FID in particular will hang until the scrub completes) so it is better to do this during a scheduled outage if possible. Cheers, Andreas -- Andreas Dilger Lustre Software Architect Intel High Performance Data Division

On 2014/10/29, 11:17 AM, "DEGREMONT Aurelien" <aurelien.degremont(a)cea.fr&gt; wrote: Sorry if my previous answer wasn't clear - if you rename the OI.16 file to a backup, then it will create multiple OI.16.n files as is the default for 2.3+. Cheers, Andreas -- Andreas Dilger Lustre Software Architect Intel High Performance Data Division