Confirm, duplicate entry gone, but the 2.2tb issue is still there.
Areca connected drives are not working with this plugin, they must be started from the command line. Because the Areca doesn't respond to smartctrl, the preclear script asks twice for you to press "Yes" before continuing the preclear. This different response confuses the plugin, and it appears to never start. Here is the first response at the command line.
Pre-Clear unRAID Disk /dev/sdo
################################################################## 1.15
smartctl may not be able to run on /dev/sdo with the -d ata option.
however this should not affect the clearing of a disk.
smartctl exit status = 2
smartctl 6.2 2013-07-26 r3841 [x86_64-linux-4.0.4-unRAID] (local build)
Copyright (C) 2002-13, Bruce Allen, Christian Franke, www.smartmontools.org
Read Device Identity failed: Invalid argument
A mandatory SMART command failed: exiting. To continue, add one or more '-T permissive' options.$
Do you wish to continue?
(Answer Yes to continue. Capital 'Y', lower case 'es'):
Can you try running preclear with -d areca and see if it works?