I just recently purchased 3x 18TB drives to increase my storage capacity. I'm lucky I did because while preclearing the drives on of my data drive had the reallocated sector count increase from 0 to 8 while jellyfin was doing a full refresh of meta data. Preemptively I moved the data off that drive until the preclears were done. While moving data the reallocated sector count remained at 8. I started a parity check and the sector count increased again to 16.

I have 9 total drives at 6TB each including 2 parity drives. My plan was to replace the 2 parity drives and 1 data drive with the 18TB buy replacing the parity drives 1 at a time first then add the data drive while doing parity checks in-between the replacements.

But now I have this failing drive and was wondering if I should still proceed with my plan or should I change it. The failing drive has no data on it.

If the drive is still not giving read errors, you should be able to do what you planned, and since you have dual parity, even if there are read errors during the first parity drive upgrade, they should be corrected by the second parity.

Another option would be to do a parity swap; you would need to disable that disk first, and the array would be offline during the parity copy part, but I think the other option would be fine in this case, and that way the array will remain online.

Unless I'm misunderstanding the parity swap process you are moving the old parity drive to be a new data drive by reconstructing the data on the old parity drive. I don't want my old parity drives part of the array after upgrade. I'm looking to replace 3 of my 6TB drives with 3 18TB drives.

Is there a process for copying the parity drive without reconstructing the data drive.

4 minutes ago, sgibbers17 said:

Is there a process for copying the parity drive without reconstructing the data drive.

No. You just rebuild the parity onto a new parity drive while you are protected by the second parity drive.. Having done that you can then upgrade the other parity drive. Finally replace the data drive.

Not much point in doing parity checks in between the steps unless you think your hardware has issues so that the parity/data rebuilds are likely to have errors.

Step 15 "The data drive rebuild begins. Parity is now valid, and the array is started."

"Once again, you can patiently watch the progress, takes a long time too! All of the contents of the old data drive are now being reconstructed on what used to be your parity drive, but is now assigned as the replacement data drive."

The way I read that is that the my old 6TB parity driver will be reconstructed with the data from the old data drive. If I don't plan on using the old 6TB drives should I just do a new config with changing the 2 parity drives and the empty data drive and doing a fresh parity calc. I don't have anything stored on my server that can't be replaced.

1 hour ago, sgibbers17 said:

The way I read that is that the my old 6TB parity driver will be reconstructed with the data from the old data drive.

That is correct, if you don't need its data you can just do a new config without the old disk, just note that the array will be unprotected until the sysnc finishes.