On Mon, 23 Nov 2009, Ric Wheeler wrote: > What we need is to pass down cache flush commands (ATA_CACHE_FLUSH_EXT is what > flushed the cache for ATA/S-ATA devices). Even with a command-queue length of 1, > the write cache a USB connected s-ata drive would still loose data on power off > without this kind of support. You can't send ATA commands directly over a USB connection without using a passthru protocol of some sort. Some of the USB interfaces in various drive enclosures support such a protocol but a lot of them don't. Of course, you _can_ send SCSI's SYNCHRONIZE CACHE command. What ATA/SATA command (if any) the drive's USB interface will translate it into is known only to the interface's manufacturer. Nevertheless, that's what we've been depending on because that's what the sd driver uses. Alan -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
