linux usb clarification 391

In a message on Sun, 12 Feb 2006 16:38:53 +0100, wrote :

Both the USB and Firewire Mbutt Storage drivers use the 'SCSI Disk Abstraction Layer' (sd.o) in the Linux kernel.

dev-sda1 is the first *parbreastion* on the first SCSI device. Your floppy does not have a parbreastion table (the file system takes up the whole raw device) and your USB memory stick does. This is typical for these devices. Your *could* put a parbreastion table on a floppy, but it is silly. You can also dispense with the parbreastion table on your USB memory stick, but this might cause problems when you 'share' your USB memory stick with your friends'.

dev-sda1 is the first *parbreastion* on the first SCSI device. There is no mapping (even with real SCSI devices) to specific controllers or specific targets (with thedev-sd?? mapping, that is, -- there is another set of device files that work differently and I don't know if that is meaningful for 'fake' SCSI devices).

dev-sda is the first SCSI disk -- the first 'thing' that glomes onto the sd.o module. dev-sda refers to the *whole* disk.dev-sda{1...15} refers to the 15 possible parbreastions on the disk, buttuming it has a parbreastion table on it.

Note: the SATA drivers and various RAID controllers, both SATA-IDE and SCSI, also use the SCSI Disk Abstraction Layer, so don't be surprised when you

When a disk is mapped to the sd.o module (either when a SCSI driver is loaded and it scans a SCSI controller's bus or if one of the other drivers using the SCSI Disk Abstraction Layer maps a disk drive (disk drive can equal a USB memory stick, a USB flash card, the memory in a USB camera, a SATA disk, a RAID array, or a USB floppy disk, or a USB the first one,dev-sdb to the second one, etc. Note it is possible to, for example, have the first SCSI controller only have non-disks on it (CD-ROM (-dev-sr), Tape drives (-dev-st), or something else (scanner for example)dev-sg) and the *second* controler could have a disk. This disk would bedev-sda, even though it is Not the first controller. dev-sda need not be the first target either. It is only the first disk-like thing buttociated with sd.o without regard to controller or target.