ASM磁盘组是作为一个逻辑单元管理的一个ASM磁盘池。与其他任何LVM一样，ASM管理大量物理卷并将其作为一个或多个逻辑卷呈交给Oracle。物理卷可以是实际的磁盘或磁盘的分区，或者是隶属操作系统的卷管理器的卷。无论采用哪种方式，都不能使用任何文件系统格式化，必须是裸设备。
在Linux上，ASM能引用磁盘作为裸设备，或通过使用ASMLib软件。
直接使用裸设备的方法：
1. 在RHEL6以前的可以直接通过rawdevices的管理方法，系统安装后默认已存在/etc/init.d/rawdevices和/etc/sysconfig/rawdevices这两个文件。
# cat /etc/RedHat-release
Red Hat Enterprise Linux Server release 5.8 (Tikanga)
# rpm -qf /etc/init.d/rawdevices /etc/sysconfig/rawdevices
initscripts-8.45.42-1.el5
initscripts-8.45.42-1.el5
# cat /etc/init.d/rawdevices
#!/bin/bash
#
# rawdevices This shell script assignes rawdevices to block devices
#
# chkconfig: 345 56 44
# description: This scripts assignes raw devices to block devices
# (such as hard drive partitions). This is for the use
# of applications such as Oracle. You can set up the
# raw device to block device mapping by editing
# the file /etc/sysconfig/rawdevices.
# config: /etc/sysconfig/rawdevices
[ -f /bin/raw ] || exit 0
[ -f /etc/sysconfig/rawdevices ] || exit 0
# Exit if the file just has the default comments.
LC_ALL=C /bin/egrep -q -v "^ *#" /etc/sysconfig/rawdevices 2>/dev/null || exit 0
. /etc/init.d/functions
function assign_raw()
{
LC_ALL=C egrep -v '^ *#' /etc/sysconfig/rawdevices |
while read RAW BLOCK; do
if [ -n "$RAW" -a -n "$BLOCK" ]; then
rawdirname=${RAW%/*}
if [ "$rawdirname" = "/dev" -a -d /dev/raw ]; then
echo $" Please correct your /etc/sysconfig/rawdevices:"
echo $" rawdevices are now located in the directory /dev/raw/ "
echo $" If the command 'raw' still refers to /dev/raw as a file."
echo $" you'll have to upgrade your util-linux package"
exit 0
fi
if [ "$rawdirname" = "/dev/raw" -a -f /dev/raw ]; then
echo $" Please correct your /etc/sysconfig/rawdevices:"
echo $" rawdevices are now located in the directory /dev/raw/ "
echo $" If the command 'raw' still refers to /dev/raw as a file."
echo $" you'll have to upgrade your util-linux package"
exit 0
fi
echo " $RAW --> $BLOCK";
raw $RAW $BLOCK
fi
done
}
# See how we were called.
case "$1" in
start)
# Assign devices
echo $"Assigning devices: "
assign_raw
#添加以下两行(默认不存在)，即默认情况下生成的裸设备为root所有，
#所以必须修改属主，否则oracle用户无法使用裸设备
sleep 5
chown -R oracle:oinstall /dev/raw/
echo $"done"
;;
stop)
# No action to be taken here
;;
status)
ID=`id -u`
if [ $ID -eq 0 ]; then
raw -qa
else
echo $"You need to be root to use this command ! "
fi
;;
restart|reload)
$0 start
;;
*)
echo $"Usage: $0 {start|stop|status|restart}"
exit 1
esac
exit 0
------------------------------------------------------
# vi /etc/sysconfig/rawdevices //映射将要绑定的裸设备
/dev/raw/raw10 /dev/sda10
/dev/raw/raw11 /dev/sda11
/dev/raw/raw12 /dev/sda12
/dev/raw/raw13 /dev/sda13
/dev/raw/raw14 /dev/sda14
# chkconfig rawdevices on
# service rawdevices start
Assigning devices:
/dev/raw/raw10 --> /dev/sda10
/dev/raw/raw10: bound to major 8, minor 10
/dev/raw/raw11 --> /dev/sda11
/dev/raw/raw11: bound to major 8, minor 11
/dev/raw/raw12 --> /dev/sda12
/dev/raw/raw12: bound to major 8, minor 12
/dev/raw/raw13 --> /dev/sda13
/dev/raw/raw13: bound to major 8, minor 13
/dev/raw/raw14 --> /dev/sda14
/dev/raw/raw14: bound to major 8, minor 14
done
# ls -l /dev/raw/
total 0
crw-rw----. 1 oracle oinstall 162, 10 May 27 08:37 raw10
crw-rw----. 1 oracle oinstall 162, 11 May 27 08:37 raw11
crw-rw----. 1 oracle oinstall 162, 12 May 27 08:37 raw12
crw-rw----. 1 oracle oinstall 162, 13 May 27 08:37 raw13
crw-rw----. 1 oracle oinstall 162, 14 May 27 08:37 raw14
crw-rw----. 1 oracle oinstall 162, 0 May 27 08:19 rawctl
# raw -qa
/dev/raw/raw10: bound to major 8, minor 10
/dev/raw/raw11: bound to major 8, minor 11
/dev/raw/raw12: bound to major 8, minor 12
/dev/raw/raw13: bound to major 8, minor 13
/dev/raw/raw14: bound to major 8, minor 14