homePath='/dev/splunk/var/lib/splunk/audit/db' of index=_audit on unusable filesystem.
Validating databases (splunkd validatedb) failed with code '1'. If you cannot resolve the issue(s) above after consulting documentation, please file a case online at http://www.splunk.com/page/submit_issue
That's documented at https://docs.splunk.com/Documentation/Splunk/7.3.2/Troubleshooting/FSLockingIssues