On Mon, Mar 06, 2023 at 11:12:14AM -0500, Theodore Ts'o wrote: > What HDD vendors want is to be able to have 32k or even 64k *physical* > sector sizes. This allows for much more efficient erasure codes, so > it will increase their byte capacity now that it's no longer easier to > get capacity boosts by squeezing the tracks closer and closer, and > their have been various engineering tradeoffs with SMR, HAMR, and > MAMR. HDD vendors have been asking for this at LSF/MM, and in other > venues for ***years***. I've been reminded by a friend who works on the drive side that a motivation for the SSD vendors is (essentially) the size of sector_t. Once the drive needs to support more than 2/4 billion sectors, they need to move to a 64-bit sector size, so the amount of memory consumed by the FTL doubles, the CPU data cache becomes half as effective, etc. That significantly increases the BOM for the drive, and so they have to charge more. With a 512-byte LBA, that's 2TB; with a 4096-byte LBA, it's at 16TB and with a 64k LBA, they can keep using 32-bit LBA numbers all the way up to 256TB.
