I would assume with arrays they will use a different way to calculate parity or have higher redundancy to compensate the risk.

Can't wait to see this bad boy on serverpartdeals in a couple years if I'm still alive

This hard drive is so big, it's got its own area code

if I'm still alive

That goes without saying, unless you anticipate something.

I'm not in the know of having your own personal data centers so I have no idea. ... But how often is this necessary? Does accessing your own data on your hard drive require a scrub? I just have a 2tb on my home pc. Is the equivalent of a scrub like a disk clean up?

Howdy!

twenty!?

I don't have experience with windows server, but that indeed sounds like these are dead. you could check them with some pendrive bootable live linux, whether it sees them, like gparted's edition, in case windows just hides them because it blacklisted them or something

If there's higher redundancy, then they are already giving up on density.

We've pretty much covered the likely ways to calculate parity.

I would think most standard consumers are not using HDDs at all.

It's like the petronas towers, everytime they're finished cleaning the windows they have to start again

You usually scrub you pool about once a month, but there are no hard rules on that. The main problem with scrubbing is, that it puts a heavy load on the pool, slowing it down.

Accessing the data does not need a scrub, it is only a routine maintenance task.
A scrub is not like a disk cleanup. With a disk cleanup you remove unneeded files and caches, maybe de-fragment as well. A scrub on the other hand validates that the data you stored on the pool is still the same as before. This is primarily to protect from things like bit rot.

There are many ways a drive can degrade. Sectors can become unreadable, random bits can flip, a write can be interrupted by a power outage, etc. Normal file systems like NTFS or ext4 can only handle this in limited ways. Mostly by deleting the corrupted data.

ZFS on the other hand is built using redundant storage. Storing the data spread over multiple drives in a special way allowing it to recover most corruption and even survive the complete failure of a disk. This comes at the cost of losing some capacity however.