On Thu, 11 Nov 2004, Sara Fonseca wrote: > Hi, > > i was watching the packets transfered from the host to a pen-drive and > from the pen drive to the host. Seems that the pen drive uses the > RBC(reduced block command). How does that relate to SCSI-2 commands? > Is it a subset?
What did you see that led you to this conclusion? The main difference between RBC (Subclass = 0x01) and Transparent SCSI (Subclass = 0x06) is that with RBC all commands are padded with 0's to 12 bytes and with Transparent SCSI they aren't. (Except that the Windows USB stack has a bug that causes it to pad REQUEST SENSE commands even when it shouldn't.) There are a few other minor differences involving whether to use the 6-byte or 10-byte versions of commands like MODE SENSE. The rule followed by Windows is to use the 6-byte commands for Transparent SCSI and the 10-byte commands for everything else. In general, the meaning of the Subclass codes other than Transparent SCSI is not well defined. My advice is to ignore the matter and stick with Transparent SCSI. All USB mass storage drivers will recognize it. Alan Stern ------------------------------------------------------- This SF.Net email is sponsored by: Sybase ASE Linux Express Edition - download now for FREE LinuxWorld Reader's Choice Award Winner for best database on Linux. http://ads.osdn.com/?ad_id=5588&alloc_id=12065&op=click _______________________________________________ [EMAIL PROTECTED] To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-devel
