如果想在Linux中安装oracle软件，并且使用裸设备方式建库，那么直接使用lvcreate是不会为我们创建出字符设备的，本文主要讨论如何对逻辑卷创建字符设备。操作系统使用的是RHEL6u4 64bit
$ uname -a
Linux oracle11.cc 2.6.32-358.el6.x86_64 #1 SMP Tue Jan 29 11:47:41 EST 2013 x86_64 x86_64 x86_64 GNU/Linux
逻辑卷怎么创建略过，先看一下我当前系统有哪些逻辑卷
$ ls -l /dev/vg00/*m
lrwxrwxrwx 1 root root 7 Jul 5 20:37 /dev/vg00/control1_16m -> ../dm-9
lrwxrwxrwx 1 root root 8 Jul 5 20:37 /dev/vg00/control2_16m -> ../dm-10
lrwxrwxrwx 1 root root 8 Jul 5 20:37 /dev/vg00/redo1_128m -> ../dm-11
lrwxrwxrwx 1 root root 8 Jul 5 20:37 /dev/vg00/redo2_128m -> ../dm-12
lrwxrwxrwx 1 root root 8 Jul 5 20:37 /dev/vg00/redo3_128m -> ../dm-13
lrwxrwxrwx 1 root root 8 Jul 5 20:37 /dev/vg00/spfile_16m -> ../dm-14
lrwxrwxrwx 1 root root 7 Jul 5 20:37 /dev/vg00/sysaux_1024m -> ../dm-5
lrwxrwxrwx 1 root root 7 Jul 5 20:37 /dev/vg00/system_1024m -> ../dm-4
lrwxrwxrwx 1 root root 7 Jul 5 20:37 /dev/vg00/temp_512m -> ../dm-6
lrwxrwxrwx 1 root root 7 Jul 5 20:37 /dev/vg00/undo_512m -> ../dm-7
lrwxrwxrwx 1 root root 7 Jul 5 20:37 /dev/vg00/user_16m -> ../dm-8
使用udev的方式把块设备文件映射成字符设备文件
如果在rhel5中可以使用/etc/sysconfig/rawdevices 这个文件写映射，挺方便的。但是RHEL6中就找不到这个了。那么我们看一下怎么使用udev方式对他们映射的吧。
首先找到块设备的 MAJOR 和 MINOR
因为上面/dev/vg00 目录下的文件是软连接，所以需要直接查看所对应的块设备文件。
# id root
uid=0(root) gid=0(root) groups=0(root)
# ls -l /dev/dm-{4,5,6,7,8,9,10,11,12,13,14}
brw-rw---- 1 root disk 253, 10 Jul 5 20:37 /dev/dm-10
brw-rw---- 1 root disk 253, 11 Jul 5 20:37 /dev/dm-11
brw-rw---- 1 root disk 253, 12 Jul 5 20:37 /dev/dm-12
brw-rw---- 1 root disk 253, 13 Jul 5 20:37 /dev/dm-13
brw-rw---- 1 oracle dba 253, 14 Jul 5 20:37 /dev/dm-14
brw-rw---- 1 root disk 253, 4 Jul 5 20:37 /dev/dm-4
brw-rw---- 1 root disk 253, 5 Jul 5 20:37 /dev/dm-5
brw-rw---- 1 root disk 253, 6 Jul 5 20:37 /dev/dm-6
brw-rw---- 1 root disk 253, 7 Jul 5 20:37 /dev/dm-7
brw-rw---- 1 root disk 253, 8 Jul 5 20:37 /dev/dm-8
brw-rw---- 1 root disk 253, 9 Jul 5 20:37 /dev/dm-9
其中第五列就是MAJOR 第六列就是MINOR，比如/dev/dm-0的 MAJOR就是253，MINOR就是0
那么这两个参数是怎么使用的呢？
通过下面方法打开规则文件，范例都在里面呢。
# vi /etc/udev/rules.d/60-raw.rules
（我对60-raw.rules原文进行缩进处理）
# Enter raw device bindings here.
#
# An example would be:
# ACTION=="add", KERNEL=="sda", RUN+="/bin/raw /dev/raw/raw1 %N"
# to bind /dev/raw/raw1 to /dev/sda, or
# ACTION=="add", ENV{MAJOR}=="8", ENV{MINOR}=="1", RUN+="/bin/raw /dev/raw/raw2 %M %m"
# to bind /dev/raw/raw2 to the device with major 8, minor 1.
范例中提到，有两种写raw映射的方法。第一种就是本文将要使用的。第二种一看就能看明白。
写法比较固定，例如：
ACTION=="add", ENV{MAJOR}=="253", ENV{MINOR}=="4", RUN+="/bin/raw /dev/raw/raw1 %M %m"
ACTION=="add", ENV{MAJOR}=="253", ENV{MINOR}=="5", RUN+="/bin/raw /dev/raw/raw2 %M %m"
ACTION=="add", ENV{MAJOR}=="253", ENV{MINOR}=="6", RUN+="/bin/raw /dev/raw/raw3 %M %m"
ACTION=="add", ENV{MAJOR}=="253", ENV{MINOR}=="7", RUN+="/bin/raw /dev/raw/raw4 %M %m"
ACTION=="add", ENV{MAJOR}=="253", ENV{MINOR}=="8", RUN+="/bin/raw /dev/raw/raw5 %M %m"
ACTION=="add", ENV{MAJOR}=="253", ENV{MINOR}=="9", RUN+="/bin/raw /dev/raw/raw6 %M %m"
ACTION=="add", ENV{MAJOR}=="253", ENV{MINOR}=="10", RUN+="/bin/raw /dev/raw/raw7 %M %m"
ACTION=="add", ENV{MAJOR}=="253", ENV{MINOR}=="11", RUN+="/bin/raw /dev/raw/raw8 %M %m"
ACTION=="add", ENV{MAJOR}=="253", ENV{MINOR}=="12", RUN+="/bin/raw /dev/raw/raw9 %M %m"
ACTION=="add", ENV{MAJOR}=="253", ENV{MINOR}=="13", RUN+="/bin/raw /dev/raw/raw10 %M %m"
ACTION=="add", ENV{MAJOR}=="253", ENV{MINOR}=="14", RUN+="/bin/raw /dev/raw/raw11 %M %m"
# start_udev
Starting udev: [ OK ]
查询一下，发现裸设备已经出现了，但是权限还是root，需要在60-raw.rules 中添加授权语句。
# ls -l /dev/raw
total 0
crw-rw---- 1 root disk 162, 1 Jul 6 00:01 raw1
crw-rw---- 1 root disk 162, 10 Jul 6 00:01 raw10
crw-rw---- 1 root disk 162, 11 Jul 6 00:01 raw11
crw-rw---- 1 root disk 162, 2 Jul 6 00:01 raw2
crw-rw---- 1 root disk 162, 3 Jul 6 00:01 raw3
crw-rw---- 1 root disk 162, 4 Jul 6 00:01 raw4
crw-rw---- 1 root disk 162, 5 Jul 6 00:01 raw5
crw-rw---- 1 root disk 162, 6 Jul 6 00:01 raw6
crw-rw---- 1 root disk 162, 7 Jul 6 00:01 raw7
crw-rw---- 1 root disk 162, 8 Jul 6 00:01 raw8
crw-rw---- 1 root disk 162, 9 Jul 6 00:01 raw9
crw-rw---- 1 root disk 162, 0 Jul 6 00:01 rawctl
添加授权语句
KERNEL=="raw[0-9]*", NAME="raw/%k" OWNER="oracle" GROUP="dba", MODE="0660"
# star_udev
# ll /dev/raw
total 0
crw-rw---- 1 oracle dba 162, 1 Jul 6 00:05 raw1
crw-rw---- 1 oracle dba 162, 10 Jul 6 00:05 raw10
crw-rw---- 1 oracle dba 162, 11 Jul 6 00:05 raw11
crw-rw---- 1 oracle dba 162, 2 Jul 6 00:05 raw2
crw-rw---- 1 oracle dba 162, 3 Jul 6 00:05 raw3
crw-rw---- 1 oracle dba 162, 4 Jul 6 00:05 raw4
crw-rw---- 1 oracle dba 162, 5 Jul 6 00:05 raw5
crw-rw---- 1 oracle dba 162, 6 Jul 6 00:05 raw6
crw-rw---- 1 oracle dba 162, 7 Jul 6 00:05 raw7
crw-rw---- 1 oracle dba 162, 8 Jul 6 00:05 raw8
crw-rw---- 1 oracle dba 162, 9 Jul 6 00:05 raw9
crw-rw---- 1 root disk 162, 0 Jul 6 00:05 rawctl
#
# raw -qa
/dev/raw/raw1: bound to major 253, minor 4
/dev/raw/raw2: bound to major 253, minor 5
/dev/raw/raw3: bound to major 253, minor 6
/dev/raw/raw4: bound to major 253, minor 7
/dev/raw/raw5: bound to major 253, minor 8
/dev/raw/raw6: bound to major 253, minor 9
/dev/raw/raw7: bound to major 253, minor 10
/dev/raw/raw8: bound to major 253, minor 11
/dev/raw/raw9: bound to major 253, minor 12
/dev/raw/raw10: bound to major 253, minor 13
/dev/raw/raw11: bound to major 253, minor 14
http://blog.itpub.net/23135684/viewspace-696799/
http://www.dswcomputersystems.co.uk/howtos-2/informix-howtos/configuring-raw-disks-on-rhel-6/
原文地址：http://xiaoyiyi.blog.51cto.com/1351449/1435125
