I'd assume that all the computers/hard drives have FDE on them, so wiping the headers/keys would suffice to make the entire disk unreadable.

Not an acceptable method of sanitation above certain classification levels, only physical destruction of the medium is sufficient.

There are shredders and V-shaped vice/press devices built for this purpose and such facilities will have them ready and waiting to be used.

Yup, anything sensitive should be encrypted but defense in depth is the name of the game.

I’d be surprised if they didn’t have a bulk eraser on site.

Destroying the encryption key for a harddrive takes less than a second. Are disks really not fully encrypted when they store sensitive information?

First you wipe the keys, then you wipe the drive... then you physically destroy it just to be sure.

how good is a hole on a platter. I suspect, some data can still be recoverable. A photograph with some parts missing is better than no photo.

I was never privy to the true details but I suspect that they are making good use of torx screwdrivers and abrasives (wire brush, sandpaper, etc) right about now. It's slower but they have a fairly good amount of time to deal with it.

If they have time they're wiping things first.

You can also just burn them. It's not the Taliban they're worried about, it's the Russian and Chinese spies who will sneak in and pocket stuff, but that's mostly dealt with with policies that keep the kind of info those people would want off of hard drives in an unrelated nation.

Bending is generally considered safer, as it prevents rotating the drive, making any recovery attempts prohibitively slow and expensive.

Most defense contractor infosec departments will accept video evidence of HDD destruction so long as they do a walk through showing serial numbers so they know which drives are accounted for.

As a result there's tons of videos that the public will never see of the world's heaviest presses, shears and brakes being used to decimate lines of hard drives. When you run a shipyard it's cheaper to just bend hard drives than it is to ship them back to HQ and have infosec deal with them.

One of my jobs as an intern was to take a list of serial numbers and watch the video walk-through and confirm the list matched the drives.

Is the substrate glass? Does it shatter when you drill the hole? If so, drilling might be fairly good.

It's a mix according to https://en.wikipedia.org/wiki/Hard_disk_drive_platter

depending how you're doing it, it's actually quite difficult to properly drill a hard drive.