[SOLVED] Proper procedure to upgrade Parity HD and Data HD in a 4-bay system

[NeoMod]

Hello everyone,
 

I have been using UNRAID for some months now, and I am happy with it, and today I have some questions on how to properly proceed with an HD change for both a Parity Drive and a Data Drive.
 

I have read all the documents (here and here ) but before doing anything stupid I would like to receive confirmation since I would hate myself for losing data over such a “simple” procedure.
 
 I am currently running UNRAID on an HP Microserver Gen8 with the following configuration:
 
 - 1 SSD Cache Drive 
 - 4 WD RED “2TB” Data Drives organized as: 
 ------ 1 "2TB" Parity Drive
 ------ 3 "2TB" Data Drive
  
What I would like to achieve is:
-         Upgrade the Parity Drive with a 4TB WD RED
-         Upgrade the Data Drive with a 4TB WD RED

In brief, I would like to upgrade one of my Data Drive with a larger one (from 2TB to 4TB) but in order to do I first need to upgrade the Parity Drive to the corresponding maximum size (again, from 2TB to 4TB).
 
 I have read about the “Parity Swap” procedure, and I was preparing to do so but then I also read that:
 
 

Quote

If all you want to do is replace your Parity drive with a larger one, then you don't need the Parity Swap procedure. Just remove the old parity drive and add the new one, and start the array. The process of building parity will immediately begin. (If something goes wrong, you still have the old parity drive that you can put back!)

 

Quote

If the replacement drive is the same size or larger, UP TO the same size as the parity drive, then there is a simple procedure for that, called Replacing a Data Drive. 

 

Hence, my question is: can I “split” the initial operation into two different, smaller and more secure procedures?

In particular:

1.  First step -- upgrade the Parity Drive, swapping the old 2TB for the new 4TB. This of course would require time to Rebuild and Check the Parity.
2. Second step -- once the New Parity Drive (4TB) is up and the Array (with the same old 3 Drives, 2TB each) is running fine, I would proceed with the “Replacing a Data Drive” procedure. Once again, this would require time to do all the operations and the Array won’t be available. I know, and I’m fine with planning some downtime in advance.

 

So, is this “2-steps 2-procedures” technically correct, or I’m completely wrong? (and if so, I would like to ask for directions in the right way).

 

Thanks in advance.

Edited May 14, 2022 by NeoMod
typo, marked as solved

[itimpi]

The 2 step procedure is the way to go.  
 

At each stage make sure you keep the disk just removed with its contents intact until that stage has successfully completed as that gives you a fallback option if anything happens to go wrong.

[NeoMod]

Thank you very much @itimpi for the quick and reassuring answer!

I will proceed with the step procedure and complete the upgrade.