[dannyw]

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.

[throwaway09223]

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.