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裸设备，是没有经过格式化的分区或磁盘，也叫裸分区（原始分区），不被Unix通过文件系统来读取的特殊字符设备。它由应用程序负责对它进行读写操作。不经过文件系统的缓冲，是不被操作系统直接管理的设备。由于跨过操作系统管理，使得I/O效率更高。在基于SUSE Linux 10上安装Oracle 10g RAC的话，由于Oracle 10g 不支持将ocr与votingdisk 存放在ASM 磁盘中，因此，依然需要为其使用裸设备方式。SUSE Linux裸设备的配置与其他的Linux稍有差异，下面将具体描述。
1、先对磁盘进行分区，sdd如下面的方法炮制
#下面的示例中使用sdc和sdd来用作裸设备，一块用于ocr,一块用于votingdisk
bo2dbp:~ # fdisk /dev/sdc
Device contains neither a valid DOS partition table, nor Sun, SGI or OSF disklabel
Building a new DOS disklabel. Changes will remain in memory only,
until you decide to write them. After that, of course, the previous
content won’t be recoverable.
Warning: invalid flag 0x0000 of partition table 4 will be corrected by w(rite)
Command (m for help): n
Command action
e extended
p primary partition (1-4)
p
Partition number (1-4):
Value out of range.
Partition number (1-4):
Value out of range.
Partition number (1-4): 1
First cylinder (1-200, default 1):
Using default value 1
Last cylinder or +size or +sizeM or +sizeK (1-200, default 200):
Using default value 200
Command (m for help): w
The partition table has been altered!
Calling ioctl() to re-read partition table.
Syncing disks.
2、分区后的结果
bo2dbp:~ # fdisk -l /dev/sdc
Disk /dev/sdc: 209 MB, 209715200 bytes
64 heads, 32 sectors/track, 200 cylinders
Units = cylinders of 2048 * 512 = 1048576 bytes
Device Boot Start End Blocks Id System
/dev/sdc1 1 200 204784 83 Linux
bo2dbp:~ # fdisk -l /dev/sdd
Disk /dev/sdd: 209 MB, 209715200 bytes
64 heads, 32 sectors/track, 200 cylinders
Units = cylinders of 2048 * 512 = 1048576 bytes
Device Boot Start End Blocks Id System
/dev/sdd1 1 200 204784 83 Linux
3、配置裸设备
bo2dbp:~ # vi /etc/raw
# /etc/raw
#
# sample configuration to bind raw devices
# to block devices
#
# The format of this file is:
# raw<N>:<blockdev>
#
# example:
# ———
# raw1:hdb1
#
# this means: bind /dev/raw/raw1 to /dev/hdb1
#
# …
#Add new raw devices
raw1:sdc1
raw2:sdd1
4、启动裸设备
bo2dbp:~ # rcraw start
bind /dev/raw/raw1 to /dev/sdc1… done
bind /dev/raw/raw2 to /dev/sdd1… done
5、配置裸设备随系统启动
bo2dbp:~ # chkconfig raw
raw on
#修改裸设备的权限与所有者，尽管该操作会修改，但重启之后将失效。永久修改见第7点
bo2dbp:~ # chown oracle:dba /dev/raw/raw[1-2]
bo2dbp:~ # chmod 660 /dev/raw/raw[1-2]
6、测试裸设备
bo2dbp:~ # dd if=/dev/zero of=/dev/raw/raw1 bs=1024k count=200
dd: writing `/dev/raw/raw1′: No space left on device
200+0 records in
199+0 records out
209698816 bytes (210 MB) copied, 2.59567 seconds, 80.8 MB/s
7、修改裸设备启动后权限及所有者
#使用root用户修改/etc/udev/rules.d/50-udev-default.rules,确保raw设备的权限GROUP=”dba”, MODE=”660″, OWNER=”oracle”
#将其中包含KENREL==”raw”的记录修改为如下
KERNEL==”raw[0-9]*”, SUBSYSTEM==”raw”, NAME=”raw/%k”, GROUP=”dba”, MODE=”640″, OWNER=”oracle”
8、确认配置成功
#重启之后的状态
bo2dbp:~ # ls -hltr /dev/raw
total 0
crw-rw—- 1 root disk 162, 0 Sep 19 10:22 rawctl
crw-rw—- 1 oracle dba 162, 1 Sep 19 10:22 raw1
crw-rw—- 1 oracle dba 162, 2 Sep 19 10:22 raw2
bo2dbs:~ # /usr/sbin/raw -qa
/dev/raw/raw1: bound to major 8, minor 33
/dev/raw/raw2: bound to major 8, minor 49
