> One simple approach would be for a daemon to create a massive file filled with "MAGICBYTESMAGICBYTESMAGICBYTES...". As that data is 'written' to the drive, th

> One simple approach would be for a daemon to create a massive file filled with "MAGICBYTESMAGICBYTESMAGICBYTES...". As that data is 'written' to the drive, the drive sees that it's the magic bytes, and rather than storing the data, simply marks those sectors as no longer needed. As soon as enough sectors in a row have that designation, reformat them as non-smr, and use as regular (non-smr) disk space. You could nearly get there today with drive firmware only, and no special OS support, using TRIM. The OS can already tell the firmware what space it doesn't need, so the firmware could do what you suggest with this information. The only catch (and difference from your proposal) is that there's no way for the firmware to tell the OS that the space is currently not available, so if the OS puts pressure on that space the firmware would still need to block writes while it SMR-izes and frees the space it previously borrowed. In other words, drive firmware could use space freed by TRIM for SMR-ization caching today, with no OS modifications.