That makes sense, but is your homelab question solved? XD

1. It’s possible. But also could be appearing naturally.

2. Probably not. You may need to show us the SMART report.

3. Isolated cases are fine. If numbers are still growing, that’s a bad sign.

Working at higher performance will generate more noise.

The “time and power” gets you the high quality.

Your understanding is incorrect. Only DMSMR drives are not very good because the disk is managing zones like a black box. HMSMR are great because user have full control on how to write data, thus eliminating all the shortcomings.

I would no brainer go to a new exos.

The 20TB exos is the same grade as red pro or gold.

Yes, 18TB at $199.

https://www.bestbuy.com/site/wd-easystore-18tb-external-usb-3-0-hard-drive-black/6427995.p?skuId=6427995

You asks if you have to increase budget, but you didn’t mention how much storage space you are looking for. New drives are at 18TB $199 price point, historical low. Unless you want to buy small drives but I don’t think you’ll get the most out of your money.

You can just switch the drive between the 2 modes in just a few seconds with a command.

At this point I’d probably just go to https://www.reddit.com/r/buildapcsales/comments/17xmwu7/hdd_best_buy_wd_easystore_18tb_external_usb_30/ .

Otherwise, refurbished Exos 16/18TB if you are not a fan of shucking or WD.

Bare minimum you should look at upgrading to E5 v2. Better go v4.