I just saw his post, it's a great explanation.

It might also help to keep in mind that both regular disk drives and solid state drives remap bad sectors. Both types of disks maintain an unaddressable storage area which is used to transparently cover for faulty sectors.

In a hard drive, faulty sectors are mapped during production and stored in the p-list, and are remapped to sectors in this extra hidden area. Sectors that fail at runtime are recorded in the g-list and are likewise remapped.

Writes may usually go to the same place in a hard drive, but it's not guaranteed there either.

This is not true anymore for many recent SMR HDDs. They have a translation layer, just like flash storage.

This is because for SMR HDDs, each block can either be SMR (higher density, EXTREMELY SLOW WRITES like <10mb/s possible, erases will remove multiple blocks just like flash memory), or normal (standard density, normal write speeds).

The controller abstracts this away and does writes as normal, but while the drive is idle, the controller in the background, converts these standard blocks into SMR blocks.

This is also why SMR HDDs support TRIM.

Thanks for the info that makes a lot of sense. It looks like this tech has emerged in the time since I last did much work with disk drives.

Seems it's increasingly a bad idea to presume the implementation of internals.