UASP makes Raspberry Pi 4 disk IO 50% faster
> Without UASP, a drive is mounted as a Mass Storage Device using Bulk Only Transport (or BOT), a protocol that was designed for transferring files way back in the USB 'Full speed' days<p>Wow, holy shit, TIL.. I was always assuming that USB drives were always SCSI — they show up as 'da' (Direct Attach) on FreeBSD after all.<p>Looking at umass driver source:<p>* The driver handles 3 Wire Protocols<p>* - Command/Bulk/Interrupt (CBI)<p>* - Command/Bulk/Interrupt with Command Completion Interrupt (CBI with CCI)<p>* - Mass Storage Bulk-Only (BBB) (BBB refers Bulk/Bulk/Bulk for Command/Data/Status phases)<p>* Over these wire protocols it handles the following command protocols<p>* - SCSI<p>* - UFI (floppy command set)<p>* - 8070i (ATAPI)<p>* UFI and 8070i (ATAPI) are transformed versions of the SCSI command set.<p>Huh, they <i>are</i> pretty much always SCSI, and "bulk only" is (unsurprisingly) only a USB transport level thing that doesn't change the command set.<p>I guess "UASP" is some sort of marketing term for Command/Bulk/Interrupt then..?