I've recently built an Unraid server with the following:-

 

2tb WD Green  - Parity (Old recycled drive)

1tb WD Green - disk 2 (Old recycled Drive)

2tb WD RED - Disk 3 (old recycled Drive)

2tb WD RED - Disk 4 (New Drive)

 

120gb SSD - Cache (new)

 

I have no free sata connections.

 

I have another 3tb WD RED that was used in NAS (along with the other used WD red that's already  in the array).

 

I would like to replace the Greens in the array with REDs. 

 

After reading up the way to do it would be:

 

1. Replace the parity disk

2.  Replace Disk 2

 

I don't want to spend a fortune so ideally would like to reuse the 3tb WD Red.  - My thoughts were reuse the 3tb WD RED as the new parity drive and after parity has been rebuilt replace the Disk 2 with a new 3TB WD RED.

 

Does this seem sensible.

 

IO

 

 

 

That is correct.

 

Step 1: Replace the parity drive with the 3TB Red

Step 2: Allow it to do a full parity build

Step 3: Run a full parity check with no errors

Step 4: Replace the 1TB Green with the 2TB Green that was just the parity drive

My comment is to be thinking about your future upgrading strategy.  I can understand your desire to do this upgrade as cheap as possible at this point and reusing old drives is a definite way to achieve that.  But upping your parity drive from 2TB to 3TB can be a costly decision down the line.  You probably add two more 3TB drives to get more storage space.  (Most MB's have 6 SATA ports on them.)  But when you need more space after that, You will either be replacing those 2TB with 3TB drives and that additional 1TB will cost about three times per TB for the additional storage space compared to adding a new drive.

 

My suggestion would be that the next time you need more storage space, get at least a 6TB drive (as the minimum size) and use it for the parity drive and the old 3TB drive as the new data drive.  Then whenever you need to add a drive (or replace a failed one), use a 6TB.  That way you will minimize your cost for additional storage on a per TB basis on the long term. (In fact, drive failures might eliminate the need to even add a new drive for additional space for a long, long time.)

 

 

...

2tb WD Green  - Parity (Old recycled drive)

1tb WD Green - disk 2 (Old recycled Drive)

2tb WD RED - Disk 3 (old recycled Drive)

2tb WD RED - Disk 4 (New Drive)

 

120gb SSD - Cache (new)

...

Do you not have a disk1? Or are you thinking of parity as disk1 (it's not, it's disk0).

...

2tb WD Green  - Parity (Old recycled drive)

1tb WD Green - disk 2 (Old recycled Drive)

2tb WD RED - Disk 3 (old recycled Drive)

2tb WD RED - Disk 4 (New Drive)

 

120gb SSD - Cache (new)

...

Do you not have a disk1? Or are you thinking of parity as disk1 (it's not, it's disk0).

 

 

 

Thanks to everyone for help. But the config above is correct . Probably because I reassigned disk 1 to be the cache drive.

 

 

I've gone for the cheap option and replaced the Parity drive with 3TB drive and rebuilt it and I have a new 2tb to replace the 1tb (I'm reusing the 1TB somewhere else - it is 6 years old ).

 

I would like  to do a preclear on the new drive but how would I do it?

 

i.e. do I remove the old drive, insert the new one and then the  new drive can be precleared before starting the array - assuming I've set Unraid to maintenance mode before closedown? The FAQs isn't very clear on this bit it just says replace the drive and you can preclear it before installation.

 

 

It is not required to clear a replacement disk. Since you mention no free SATA ports, you can use another computer and another program to test the disk if you want. Disk manufacturers have diagnostics free for download.