Can I stop my array, remove a HD, replace it with a brand new HD...  Perform a pre-clear to test if it is good, then remove it and put my old HD back and restart the array?

 

(I'm out of SATA ports until my breakout cable arrives, and so I have time to kill - might as well pre-clear a couple drives I plan on using)

in theory as long as you DONT START the array it wont hurt but your array will be offline the entire time.

 

 

 

i'd just wait.

Yes, you can, .... HOWEVER ...

 

(a)  Be sure you change the settings in your array so it doesn't auto-start BEFORE you do this;

[ Settings - Disk Settings - Enable Auto-Start ... set it to NO ]

 

(b)  Be CERTAIN that you select the correct drive to pre-clear => the pre-clear utility will NOT exclude the disks in the array from the list of drives you'll get with the -l parameter.    So be absolutely certain that you know the serial number of the disk you want to pre-clear.

 

©  As already noted, the array will be unavailable for the duration of the pre-clear, which will likely be a day or longer, depending on the size of the new drive (and whether or not you do multiple cycles).