SCSI device assignments

Hi all, I've been following the various CD-RW/ide-scsi threads and they've left me a little confused as to the significance of/difference between /dev/srX and /dev/srX I've set up my DVD-ROM and DVD+RW as sr0 and sr1, everything seems to work fine after making the appropriate links, but then I haven't tried anything 'fancy'. So why do people talk about sg0 etc? What's the difference, and how/why can the same physical device be referenced through both device files? Also, is it possible to acctivate DMA for the devices even though they're running through ide-scsi? Cheers Dylan -- "Sweet moderation Heart of this nation Desert us not We are between the wars" Billy Bragg