Admin page unavailable after cancelled backup job & hard reboot, shares are working

Check out the thread at https://community.netgear.com/t5/Using-your-ReadyNAS-in-Business/Admin-page-unavailable-after-cancelled-backup-job-amp-hard/m-p/2142882 for details.

I tried the boot menu's "OS Reinstall" option which successfully recovered the admin page. In the log, it says "Volume: System volume root's usage is 99%. This condition should not occur under normal conditions. Contact technical support.", downloading the logfiles (http://rn214/dbbroker) fails with this XML file:

<xs:nml xmlns:xs="http://www.netgear.com/protocol/transaction/NMLSchema-0.9" src="browser" dst="nas" locale="en-us">
<xs:transaction ref-id="" type="0">
<xs:response ref-id="opid" status="failure">
<xs:error>
<xs:error-code>
<![CDATA[ 12008010002 ]]>
</xs:error-code>
<xs:error-cause>
<![CDATA[ Can't create zipped log ]]>
</xs:error-cause>
<xs:error-details>
<![CDATA[ Error in dlowload log ]]>
</xs:error-details>
</xs:error>
</xs:response>
</xs:transaction>
</xs:nml>

 The reason could be that the USB disk was ejected/disconnected before the backup job was really cancelled. Sandshark mentioned that in this case rsync writes to the mount point in the OS partition instead of the USB drive that should have been mounted there.

Would I have had enabled SSH shell access before running into that problem, I could have cleared up the mess. Since the RN214 did not let me do that afterwards, I had to execute a factory reset. Bummer.