USB drives mount question

Rick Stevens rstevens at vitalstream.com
Wed Jan 5 23:58:05 UTC 2005


Ken Scott wrote:
> Hi all,
> I have several USB flash drives and a USB harddrive.  Does anyone know
> why When I plug these things in the reported dev sometimes differs. 
> Sometimes it is /dev/sda or sda1 or sdb.  What is the  rule here?  I
> also noticed that it works differently on different distros running on
> the same hardware.  The same stick is assigned different devices in
> different distros even though it is plugged into the slot. Anybody know
> why?

Depends on the udev system and the distro you're using.

Firewire and USB devices are treated as though they were SCSI devices,
so they show up as "/dev/sdXp" ("sd" meaning "SCSI disk").  The "X"
indicates which SCSI disk the system detected it as.  The first
device is "sda", the second "sdb" and so on.  Different kernels will
scan the USB, firewire and SCSI buses in different orders, so the name
may vary.

The "p" above indicates the _partition_ number on the drive.  So,
"/dev/sda" refers to the ENTIRE drive, while "/dev/sda1" refers to the
first partition on the drive, just like disks.
----------------------------------------------------------------------
- Rick Stevens, Senior Systems Engineer     rstevens at vitalstream.com -
- VitalStream, Inc.                       http://www.vitalstream.com -
-                                                                    -
-                   To err is human, to moo bovine.                  -
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