Ok, so here's what happened... A friend of mine is currently ordering the necessary hardware to build his server.  Since mine is up and running, I decided to go ahead and run a preclear on his three HDDs since he received those first.  What I noticed is that with his drives now removed from my tower (they were never added to the array, only precleared then removed) is that my parity drive has changed from (sdd) to (sde).  My data disks still match up to what they were before, both (sdx) and S/N.

 

The actual S/N of the parity drive is exactly the same, so I'm pretty sure its the same drive based on that alone.  I feel like this is a non issue but am hesitant to start my array with this discrepancy.

 

Is this an o.k. thing that can happen?  The actual position of the parity drive in the tower did not change, still feeding off of the same SATA cable as it was before.  Can't quite figure out why the (sdx) would change...

 

 

Another thing to add, I have now added a 4th drive which will be my 3rd data and it's S/N matches the actual drive but the (sdx) is (sdd), which is what my Parity USED to be... Which makes me hesitant to preclear it until I have confirmation that this is a non issue.  I realize its just a parity disk, so it's not like I would overwrite data files if unRAID precleared the incorrect disk, but still...

 

 

 

 

Total non issue. Go by serial numbers in slots, and you will be fine. The sdX assignments are subject to change based on hardware reconfigurations, as you found out.

 

Always confirm what disk you are operating on by serial number, and match that up in the current session to the sd # you should be working on.

Ok good deal, that's what I was thinking.

 

Thanks jonathanm.

Actually, the drive designations (sda, sdb, etc) are assigned in the order the disks initialize themselves and are recognized by the disk controllers.

Even if you make no changes in configuration, with identical, or nearly identical drives it is very easy for the drives to present themselves as ready in a different order any time you reboot.

 

As mentioned, go by the drive model/serial number.  That is the ONLY thing that will not change.   

It is recommended you label the drives with the serial number visible.  That way, when an error occurs, you don't mess with the wrong drive.