一.检查ASMLIB是否安装成功：

检查驱动加载情况：
[root@rhel1 disks]# lsmod | grep oracleasm
oracleasm              84136  1

检查oracleasmfs文件系统：
[root@rhel1 disks]# df -a |head -1;df -a | grep oracleasm
文件系统               1K-块        已用     可用 已用% 挂载点
oracleasmfs                  0         0         0   -  /dev/oracleasm

[root@rhel1 disks]# cat /proc/filesystems | grep oracleasm
nodev   oracleasmfs

asm disk创建成功后，会在/dev/oracleasm/disks目录下有相应的文件：
[root@rhel1 disks]# pwd
/dev/oracleasm/disks
[root@rhel1 disks]# ls
VOL1  VOL2  VOL3

如果在asmlib使用过程中有报错，可以查看详细的日志信息：
/var/log/oracleasm

二.参数介绍：
instance_type=[RDBMS | ASM]
如果是ASM的话，该参数一定要是ASM。

asm_power_limit=[1 - 11]
指定了磁盘自动平衡负载的等级，数字越大，表示自动均衡能力越强。

asm_diskstring
指定了ASM实例启动时自动寻找磁盘的特征。如参数设置为/dev/mapper/*，那么ASM实例在disk group添加磁盘时会默认把所有/dev/mapper目录下的磁盘都显示出来，默认情况为NULL，也就是所有磁盘设备都显示出来。

asm_diskgroups
指定实例启动时自动MOUNT的磁盘组。

三.日常维护：
[root@rhel1 /]# /etc/init.d/oracleasm scandisks
Scanning the system for Oracle ASMLib disks:               [  OK  ]

[root@rhel1 /]# /etc/init.d/oracleasm listdisks
VOL1

[root@rhel1 /]# /etc/init.d/oracleasm querydisk -p VOL1
Disk "VOL1" is a valid ASM disk
/dev/sdb6: LABEL="VOL1" TYPE="oracleasm"

[root@rhel1 /]# fdisk -l /dev/sdb6
Disk /dev/sdb6: 4055 MB, 4055030784 bytes
255 heads, 63 sectors/track, 492 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

Disk /dev/sdb6 doesn't contain a valid partition table

SQL> set linesize 200
SQL> col name format a30
SQL> col path format a30
SQL> select group_number,disk_number,name,path from v$asm_disk;

GROUP_NUMBER DISK_NUMBER NAME                           PATH
------------ ----------- ------------------------------ ------------------------------
           1           0 ASM1                           ORCL:VOL1

SQL> select group_number,name,type,total_mb,free_mb from v$asm_diskgroup;

GROUP_NUMBER NAME                           TYPE     TOTAL_MB    FREE_MB
------------ ------------------------------ ------ ---------- ----------
           1 DG1                            EXTERN       3867        910

[root@rhel1 sbin]# ./oracleasm createdisk VOL2 /dev/sdb8
Writing disk header: done
Instantiating disk: done
[root@rhel1 sbin]# ./oracleasm createdisk VOL3 /dev/sdb9
Writing disk header: done
Instantiating disk: done
[root@rhel1 sbin]# ./oracleasm createdisk VOL4 /dev/sdb10
Writing disk header: done
Instantiating disk: done
[root@rhel1 sbin]# ./oracleasm createdisk VOL5 /dev/sdb11
Writing disk header: done
Instantiating disk: done
[root@rhel1 sbin]# ./oracleasm scandisks               
Reloading disk partitions: done
Cleaning any stale ASM disks...
Scanning system for ASM disks...
[root@rhel1 sbin]# ./oracleasm listdisks
VOL1
VOL2
VOL3
VOL4
VOL5

[oracle@rhel1 ~]$ export ORACLE_SID=+ASM1
[oracle@rhel1 ~]$ sqlplus / as sysdba

SQL*Plus: Release 10.2.0.4.0 - Production on Tue Mar 2 03:03:44 2010

Copyright (c) 1982, 2007, Oracle.  All Rights Reserved.

Connected to:
Oracle Database 10g Enterprise Edition Release 10.2.0.4.0 - Production
With the Partitioning, Real Application Clusters, OLAP, Data Mining
and Real Application Testing options

SQL> alter diskgroup DG1 add disk '/dev/oracleasm/disks/VOL2' name data02;
alter diskgroup DG1 add disk '/dev/oracleasm/disks/VOL2' name data02
*
ERROR at line 1:
ORA-15032: not all alterations performed
ORA-15031: disk specification '/dev/oracleasm/disks/VOL2' matches no disks
ORA-15014: location '/dev/oracleasm/disks/VOL2' is not in the discovery set

SQL> alter diskgroup DG1 add disk 'ORCL:VOL2' name data02;

Diskgroup altered.

ORCL关键字说明：
Linux ASMLib 的发现字符串
  ASMLib 使用发现字符串来确定 ASM 正在请求哪些磁盘。一般的 Linux ASMLib 使用 glob 字符串。字符串必须以 "ORCL:" 为前缀。磁盘通过名称来指定。可以通过发现字符串 "ORCL:VOL1" 在 ASM 中，发现以名称 "VOL1" 创建的磁盘。类似地，可以用发现字符串 "ORCL:VOL*" 来查询所有以字符串 "VOL" 开始的磁盘。
不能在发现字符串中用路径名称来发现磁盘。如果缺少前缀，那么一般的 Linux ASMLib 将完全忽略发现字符串，认为它适用于一个不同的 ASMLib。唯一的例外是空字符串 ("")，它被认为是一个全通配符。这与发现字符串 "ORCL:*" 完全等价。

[root@rhel1 sbin]# su - oracle
[oracle@rhel1 ~]$ export ORACLE_SID=+ASM1
[oracle@rhel1 ~]$ sqlplus / as sysdba

SQL*Plus: Release 10.2.0.4.0 - Production on Sun Apr 25 17:29:57 2010

Copyright (c) 1982, 2007, Oracle.  All Rights Reserved.

Connected to:
Oracle Database 10g Enterprise Edition Release 10.2.0.4.0 - 64bit Production
With the Partitioning, Real Application Clusters, OLAP, Data Mining
and Real Application Testing options

SQL> create diskgroup dg2 external redundancy disk 'ORCL:VOL3';

Diskgroup created.

SQL> select path from v$asm_disk;

PATH
--------------------------------------------------------------------------------
ORCL:VOL1
ORCL:VOL2
ORCL:VOL3

SQL> col name format a20;
SQL>  select name,state from v$asm_diskgroup;

NAME                 STATE
-------------------- ----------------------
DG1                  MOUNTED
FLASHAREA1           MOUNTED
DG2                  MOUNTED

SQL> drop diskgroup dg2 including contents;

Diskgroup dropped.

SQL> alter diskgroup dg1 add disk 'ORCL:VOL3';

Diskgroup altered.

SQL> alter diskgroup dg1 rebalance power 11;

Diskgroup altered.

SQL> alter diskgroup dg1 check all;

Diskgroup altered.

SQL> alter diskgroup dg1 check all repair;

Diskgroup altered.

SQL> select path from v$asm_disk where group_number in (select group_number from v$asm_diskgroup where name='DG1');

PATH
--------------------------------------------------------------------------------
ORCL:VOL1
ORCL:VOL3

SQL> alter diskgroup dg1 drop disk 'VOL3';  //注意这里是DISK的名字v$asm_disk.name

Diskgroup altered.

SQL> select name from v$asm_diskgroup;

NAME
--------------------
DG1
FLASHAREA1

SQL> select name from v$asm_disk;

NAME
--------------------
DGDISK1
FLASHAREADISK01

SQL> create diskgroup dg2 external redundancy disk 'ORCL:VOL3';

Diskgroup created.