how to create raw device on linux ?
Most major Linux distributions come with several raw devices
precreated. Since Linux doesn't *really* know raw devices a work
around has been created so that standard block devices (your hard disc
partitions) can be written to as raw device (that is by circumventing
the OS's file system). Because of this the partition can not have a
file system created on it, or it must be completed erased (**NOT**
deleted, that is something completely different!
Now, the connection between raw devices, other device is 1on1. You
make the connection using a init script named raw that is (in my case
using SuSE /etc/init.d/raw). You will either have to run that script
manually (with raw start) or insert it into the runlevels you need
(possibly using insserv /etc/init.d/raw). The links from block device
to raw device is made know in a flat ascii text file that ( again in
SuSE) is called raw and situated in /etc, but it may be in
/etc/sysconfig for other distributions. The lines in this text file
(probably on RH as well) have the following syntax:
raw1:hdb1
Which simply means link raw device raw1 (in /dev/raw) to disc
partition hdb1 (as in /dev/hdb1). More raw devices? Add the lines.
Make sure you do NOT go beyond the number of raw devices you find
present. If you need more you can create them using (as root) *IN THE
SAME DIRECTORY AS YOUR OTHER RAW DEVICES ARE* using 'mknod
raw<number1> c 162 <number2>' where <number1> is the same as
<number2>, but you can not make more than 255 in all. <number1/2>
stands for the minor number of the raw device, so making raw device
number 25 would be 'mknod raw25 c 162 25', raw device 156 would be
'mknod raw156 c 162 156' etc. The 'c' stand for the type of device
yout making, the number 162 is mandatory and the designated device
number for Linux raw devices. Do NOT try to make a raw (or any other)
device with a minor number (that is the second number; in the example
25 or 156) higher than 255!
Regards, R.A. Reissaus
Risdi, Amsterdam, the Netherlands
Ibm/Informix Consultants
Telefoon: +31(0)20 4942174 : Phone
Mobiel : +31(0)6 51185352 : Mobile
Fax : +31(0)20 4940795 : Fax
E-mail : r.a.reiss...@risdi.com
Website : www.risdi.com
