I did a fresh install of 5.0 rc3 -- my first unRaid setup ever -- and just added the brand new WD20EARX to the array and formatted it.  It seems to be working fine.  It automatically aligned to 4k blocks MBR.

 

Is there anything special I should be doing for this drive before adding it like I did?  Like a "preclear" or whatever?

 

Can I add my WD20EARS and HD204UI (firmware updated to latest) the same way I added the WD20EARX or do I need to run any preclear on them as well?  They are just sitting here waiting to be put it in.  Thanks.

Preclear with multiple passes to your personal "feel good" level is recommended.  {My personal choice is 3 passes...YMMV}

 

That tests the drive really well, and makes sure you don't have an out-of-the-box drive going bad with reallocated sectors, etc.

 

The other benefit is that your array won't be down for hours while the new drive is "formatted"....

 

If you pre-clear a drive, and then add it to the array, during the pre-clear the array is available, and after you add the drive -- you're without the array only for a few minutes, it won't go through the lengthy formatting process {and the array is down while it happens}

 

...Chuck