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”,, 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
我也相信爱可以排除万难;只是，万难之后，又有万难。这是我更相信的。
