Which drive to replace first? A couple weeks ago, my data drive started reporting errors and last week I noticed my parity drive is now showing errors as well. I ordered a couple of 6TB WD Reds which are coming in today. 

My question is, whether it matters which drive I should replace first (Parity or Data) and is preclearing still important. I've read that the latest version of UNRAID does some sort of test and preclear is no longer needed. 

It's been a while since I've upgraded drives. If preclear isn't necessary I'm assuming following this process should work: 

Shutdown server-&gt;Unplug old drive and connect new one--&gt; select the new drive from the dropdown--&gt;Start Array which will then automatically put things together.