Error while validating databases

The server is a fresh installation of Fedora 19 x86_64, it is a completely minimal install with nothing else really added other than vim and git. I've set SELinux to permissive, and my firewall is still blocking all incoming traffic other than SSH but I did test with it turned off and the issue remains. After installing splunk-6.0.something I ran

cd /opt/splunk/bin/
./splunk --accept-license --answer-yes

and I get

Splunk> Be an IT superhero. Go home early.

Checking prerequisites...
    Checking http port [8000]: open
    Checking mgmt port [8089]: open
    Checking configuration...  Done.
        Creating: /opt/splunk/var/run/splunk
        Creating: /opt/splunk/var/run/splunk/appserver/i18n
        Creating: /opt/splunk/var/run/splunk/appserver/modules/static/css
        Creating: /opt/splunk/var/run/splunk/upload
        Creating: /opt/splunk/var/spool/splunk
        Creating: /opt/splunk/var/spool/dirmoncache
        Creating: /opt/splunk/var/lib/splunk/authDb
        Creating: /opt/splunk/var/lib/splunk/hashDb
    Checking critical directories...    Done
    Checking indexes...
homePath='/opt/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

I'm not really sure where it gets the idea the the filesystem is unusable, I did after all just install it to the same location that it's writing to. I did not however setup a new splunk user account, but I don't think I've ever done that in the past when I've used previous versions.

Gracias.