Currently, I have a 7TB unRAID server (1 2TB Parity Drive, 3 2TB data drives, and 1 1TB data drive).  I'm running out of data space and need to add a drive, but with the increasing size of drives out there I'm not quite sure what upgrade process is best.  Is there any school of thought on what is best in these situations? 

What license do you have? How many more 2TB drives can you to your case? When do you expect to run out of space?

 

Adding additional drives is the low cost way to gain capacity. But when running out of license or bays, you'll need to enlarge the drives, starting with the parity drive.

 

I have the basic license which allows me to add one more data drive.  I currently have a tower and could physically add one more drive internally.  To add more would require me getting an actual server case or doing something more creative.  I don't expect to run out of space too soon.  This has only been incrementally happening over time.

 

You mention starting with the parity drive, which makes sense.  I haven't been researching hardware in some time.  Are the 4TB drives now the drives of choice for unRAID?  Does it make sense to replace the parity drive with a 4TB drive and then move the previous 2TB parity drive in to a data drive slot?  This would add 2TB's of space and safeguard me for the future when I look to increase more space.  It would allow me to then add 4TB data drives since the parity drive is also 4TB...correct?  It isn't a problem to replace a 2TB parity drive with a 4TB parity drive...correct? 

That's what I'd do. Replace parity with 4tb, move 2tb to spare slot.

 

In essence, you gain only 2tb but you can then start replacing smaller drives with 4tb over time, then write and repeat with 6tb or bigger next time around.

 

If you haven't already.I would strongly recommend backing up your critical data before embarking on this.

Are the 4TB drives now the drives of choice for unRAID? 

 

It depends, but, I would say, close enough. The 4TB are currently the sweet spot in terms of price per terabyte (~$25/TB for green drives, ~30/TB for NAS-type drives). And the prices keep falling now with the 6TB fully in the market.

 

It would allow me to then add 4TB data drives since the parity drive is also 4TB...correct?

Correct.

 

It isn't a problem to replace a 2TB parity drive with a 4TB parity drive...correct?

Correct.