探索ORACLE之ASM04_维护
作者：吴伟龙
一、 ASM实例相关操作：
ASM实例的管理，启动，关闭
ASM实例的启动和数据库实例的启动有严格的先后关系，ASM启动一定早于数据库实例，关闭一定晚于ASM实例，因为它是数据库数据文件存储位置。如果ASM没有起来，起数据库将会报ORA-17503；ORA-15077的错误，错误信息如下:
SQL>startup
ORA-01078:failure in processing system parameters
ORA-01565:error in identifying file '+ASMGROUP1/WWL/spfileWWL.ora'
ORA-17503:ksfdopn:2 Failed to open file +ASMGROUP1/WWL/spfileWWL.ora
ORA-15077:could not locate ASM instance serving a required diskgroup
SQL>
1.1 ASM启动的方法:
SQL>startup
ASMinstance started
TotalSystem Global Area 83886080 bytes
FixedSize 1217836 bytes
VariableSize 57502420 bytes
ASMCache 25165824 bytes
ASMdiskgroups mounted
SQL>select instance_name,status from v$instance;
INSTANCE_NAME STATUS
----------------------------
+ASM STARTED
SQL>
1.2 ASM关闭的方法 （必须先关闭数据库）
没有关闭RDBMS实例关闭ASM将报错ORA-15097，提示已连接RDBMS实例，无法关闭ASM实例，
$ export ORACLE_SID=+ASM
$ sqlplus / as sysdba
SQL> shutdown immediate
ORA-15097: cannot SHUTDOWNASM instance with connected RDBMS instance
关闭RDBMS实例状态ASM是可以正常关闭的。
$export ORACLE_SID=WWL ---先关闭在ASM上运行的RDBMS实例
$sqlplus / as sysdba
SQL> shutdown immediate
Database closed.
Database dismounted.
ORACLE instance shut down.
SQL>
$export ORACLE_SID=+ASM ---再关闭ASM实例
$ sqlplus / as sysdba
SQL> shutdown immediate
ASM diskgroups dismounted
ASM instance shutdown
SQL>
二、 ASM三种磁盘组及磁盘的添加和维护
1、ASM磁盘的添加及删除
1.1 添加这个步骤所需的磁盘（/dev/sdd -- /dev/sdm 共10块10G的盘）
1.2 通过root用户查看下当前有几个ASM磁盘，磁盘状态，实例状态
# oracleasm listdisks
VOL1
VOL2
# oracleasm querydisk VOL1
Disk"VOL1" is a valid ASM disk
# oracleasm querydisk VOL2
Disk"VOL2" is a valid ASM disk
# ls -l /dev/oracleasm/disks/*
brw-rw---- 1oracle dba 8, 17 Apr 12 05:30 /dev/oracleasm/disks/VOL1
brw-rw---- 1oracle dba 8, 33 Apr 12 05:30 /dev/oracleasm/disks/VOL2
# oracleasm status
Checking if ASMis loaded: yes
Checking if /dev/oracleasm is mounted: yes
我们已知数据库当有两块通过ASMLiB已经标记了的磁盘，并且状态是正常的
1.3 开始通过ASMLib来标记新的磁盘,用于后面的实验:
l 报错了，很经典，是由于没有创建分区导致：
# /etc/init.d/oracleasm createdisk VOL3 /dev/sdd
Marking disk"VOL3" as an ASM disk: [FAILED]
l 先创建分区方法:fdisk /dev/sdd /n/p/1/回车/回车/w，将所有磁盘都创建分区。
# /etc/init.d/oracleasmcreatedisk VOL3 /dev/sdd1
Marking disk "VOL3" as anASM disk: [ OK ] ---可以看到，能正常创建
# sh oracleasm 通过执行脚本命令，新建10个磁盘已全部完成标记
Marking disk "VOL4" as an ASM disk: [ OK ]
Marking disk "VOL5" as an ASM disk: [ OK ]
Marking disk "VOL6" as an ASM disk: [ OK ]
Marking disk "VOL7" as an ASM disk: [ OK ]
Marking disk "VOL8" as an ASM disk: [ OK ]
Marking disk "VOL9" as an ASM disk: [ OK ]
Marking disk "VOL10" as an ASM disk: [ OK ]
Marking disk "VOL11" as an ASM disk: [ OK ]
Marking disk "VOL12" as an ASM disk: [ OK ]
1.4 为ASMGROUP1磁盘组添加删除磁盘
l 查看磁盘组的状态
SQL> selectGROUP_NUMBER,NAME,STATE,TYPE from v$asm_diskgroup;
GROUP_NUMBER NAME STATE TYPE
------------------------ ----------------- -------------- --------
1 ASMGROUP1 CONNECTED NORMAL
SQL> SELECT a.name GRPNAME,b.group_number GR_NUMBER,b.disk_numberDK_NUMBER,b.name ASMFILE,b.path,b.mount_status,b.state FROM v$asm_diskgroupa,v$asm_disk b;
GRPNAME GR_NUMBER DK_NUMBER ASMFILE PATH MOUNT_S STATE
---------- ---------- ---------------------------------------- ------------------------- ------- --------
ASMGROUP1 1 0ASMGROUP1_0000 /dev/oracleasm/disks/VOL1OPENED NORMAL
ASMGROUP1 1 1ASMGROUP1_0001 /dev/oracleasm/disks/VOL2 OPENED NORMAL
l 查看磁盘组ASMGROUP1中的成员
SQL> selectgroup_number,disk_number, failgroup,name,path from v$asm_disk where FAILGROUPlike 'ASMGROUP1%';
GROUP_NUMBERDISK_NUMBER FAILGROUP NAME PATH
----------------------- ------------------------------ ----------------------------------------------------------------------
2 1 ASMGROUP1_0001 ASMGROUP1_0001 /dev/oracleasm/disks/VOL2
2 0 ASMGROUP1_0000 ASMGROUP1_0000 /dev/oracleasm/disks/VOL1
SQL>
l 添加为ASMGROUP1添加磁盘
SQL> alterdiskgroup ASMGROUP1 add disk '/dev/oracleasm/disks/VOL10';
Diskgroupaltered.
l 我们可以看到已经添加成功了
SQL> select group_number,disk_number,failgroup,name,path from v$asm_disk where FAILGROUP like 'ASMGROUP1%';
GROUP_NUMBERDISK_NUMBER FAILGROUP NAME PATH
----------------------- ------------------------------ ----------------------------------------------------------------------
2 2 ASMGROUP1_0002 ASMGROUP1_0002 /dev/oracleasm/disks/VOL10
2 1 ASMGROUP1_0001 ASMGROUP1_0001 /dev/oracleasm/disks/VOL2
2 0 ASMGROUP1_0000 ASMGROUP1_0000 /dev/oracleasm/disks/VOL1
2、ASM三种磁盘组的创建及删除（High Normal Extermal）
2.1 创建High级别的ASM磁盘组，最少需要三块磁盘来创建。
SQL> create diskgroup asmhigh high redundancy disk'/dev/oracleasm/disks/VOL3','/dev/oracleasm/disks/VOL4','/dev/oracleasm/disks/VOL5';
Diskgroupcreated.
2.2 创建Normal级别的ASM磁盘，最少需要两个磁盘来创建。
SQL> creatediskgroup asmnormal normal redundancy disk'/dev/oracleasm/disks/VOL6','/dev/oracleasm/disks/VOL7';
Diskgroupcreated.
2.3 创建Extermal级别的ASM磁盘，最少需要一个磁盘来创建。
SQL> creatediskgroup asmexternal external redundancy disk '/dev/oracleasm/disks/VOL8';
Diskgroupcreated.
2.4 查看刚才创建的磁盘状态
SQL> select name,state,type fromv$asm_diskgroup;
NAME STATE TYPE
--------------- ----------- ------
ASMGROUP1 MOUNTED NORMAL
ASMHIGH MOUNTED HIGH
ASMNORMAL MOUNTED NORMAL
ASMEXTERNAL MOUNTED EXTERN
2.5 为ASM磁盘组添加成员，在这里我们就以Normal磁盘组来进行成员添加的例子：
SQL> alter diskgroup ASMNORMAL add disk'/dev/oracleasm/disks/VOL9';
Diskgroup altered.
SQL> select group_number,disk_number,failgroup,name,path from v$asm_disk where FAILGROUP like 'ASMNORMAL%';
GROUP_NUMBER DISK_NUMBER FAILGROUP NAME PATH
------------ ----------------------------------------- ------------------------------ ----------------------------------------
4 2 ASMNORMAL_0002 ASMNORMAL_0002 /dev/oracleasm/disks/VOL9
4 1 ASMNORMAL_0001 ASMNORMAL_0001 /dev/oracleasm/disks/VOL7
4 0 ASMNORMAL_0000 ASMNORMAL_0000 /dev/oracleasm/disks/VOL6
SQL>
2.6 删除磁盘组成员，在这里我们同样以NORMAL磁盘组来进行成员删除的例子：
SQL> alter diskgroup ASMNORMAL drop disk ASMNORMAL_0002;
Diskgroup altered.
SQL> select group_number,disk_number, failgroup,name,path fromv$asm_disk where FAILGROUP like 'ASMNORMAL%';
GROUP_NUMBER DISK_NUMBER FAILGROUP NAME PATH
------------ ----------- ------------------------------ ----------------------------------------------------------------------
4 1 ASMNORMAL_0001 ASMNORMAL_0001 /dev/oracleasm/disks/VOL7
4 0 ASMNORMAL_0000 ASMNORMAL_0000 /dev/oracleasm/disks/VOL6
SQL>
三、 模拟磁盘故障
3.1 在AMSGROUP1(NORMAL类型)磁盘组中写数据
SQL> selecttablespace_name,file_name,bytes/1024/1024 M from dba_data_files;
TABLESPACE_NAMEFILE_NAME M
------------------------------------------------------------ ----------
USERS +ASMGROUP1/wwl/datafile/users.259.780215953 5
SYSAUX +ASMGROUP1/wwl/datafile/sysaux.257.780215951 230
UNDOTBS1 +ASMGROUP1/wwl/datafile/undotbs1.258.78021595 25
3
SYSTEM +ASMGROUP1/wwl/datafile/system.256.780215951 480
ASM +ASMGROUP1/wwl/datafile/asm.270.780300769 100
ASM +ASMGROUP1/wwl/datafile/asm.271.780300809 100
6 rowsselected.
如上我们可以看到，我们所有的表空间均是放在ASMGROUP1中的，一会儿我们将对表空间写如数据，并删除一磁盘。
3.2 我们查看下该表空间的默认用户
SQL> selectusername,default_tablespace from dba_users where DEFAULT_TABLESPACE='ASM';
USERNAME DEFAULT_TABLESPACE
------------------------------------------------------------
WWL ASM
3.3 在ASM表空间写入数据。
通过WWL用户登录到系统创建一张表，用来测试.
SQL> connwwl/wwl
Connected.
SQL> createtable wwl (id varchar(5),name varchar(10));
Table created.
SQL> begin
2 fori in 1..1000 loop
3 insert into wwl values (15,'wwl15');
4 endloop;
5 end;
6 /
PL/SQLprocedure successfully completed.
我们创建了一张wwl的表，并且插入了1000行数据
SQL> selectcount(*) from wwl;
COUNT(*)
----------
1000
3.4 模拟磁盘突然损坏
[root@wwl ~]#oracleasm deletedisk VOL2;
Clearing diskheader: done
Dropping disk:done
[root@wwl ~]#
仔细看下面，我们通过如上的命令删除了VOL2后，现在只认到一个磁盘了。
SQL> selectgroup_number,disk_number, failgroup,name,path from v$asm_disk where FAILGROUPlike 'ASMGROUP%';
GROUP_NUMBERDISK_NUMBER FAILGROUP NAME PATH
----------------------- ------------------------------ ----------------------------------------------------------------------
2 0 ASMGROUP1_0000 ASMGROUP1_0000 /dev/oracleasm/disks/VOL1
SQL>
但是我们的实例和我们刚才创建的表数据都没有丢失，这就是冗余的好处，NORMAL模式它是用牺牲一块磁盘的空间来保障数据的安全性的，hight模式是至少牺牲一块硬盘来保障数据的安全性。
SQL> selectcount(*) from wwl;
COUNT(*)
----------
1000
3.5 而且业务是不会中断的，但是在日志和硬盘指示灯上会有告警：
ASM日志信息如下：
WARNING:offlining disk 2.3916240783 (ASMGROUP1_0002) with mask 0x1
NOTE: PSTupdate: grp = 2, dsk = 2, mode = 0x6
NOTE: cacheclosing disk 2 of grp 2: ASMGROUP1_0002
NOTE: PSTupdate: grp = 2
NOTE: erasingheader on grp 2 disk ASMGROUP1_0002
3.6 这个时候我们需要尽快更换新的硬盘，因为发生这问题之后如果另外一个磁盘再损坏的话那将是不可弥补的数据丢失，更换新硬盘后，数据将会再次进行同步。
3.7
四、 ASM别名管理
别名就是外号，比如说当系统自动产生的名称太过复杂不怎么好记，DBA可以通过别名，为它创建一个简单化的名称，而又不会对其现有名称造成任何影响。ASM中创建别名是通过alter diskgroup的alias子句实现，支持增加/修改/删除等多项操作。V$ASM_ALIAS视图中可以查询到当前实例中创建的别名。
4.1 添加别名
SQL> alter diskgroup ASMGROUP1 add alias'+ASMGROUP1/wwl/datafile/asm01.dbf' for'+ASMGROUP1/wwl/datafile/asm.270.780300769';
Diskgroup altered.
4.2 修改别名
SQL> alter diskgroup ASMGROUP1 renamealias '+ASMGROUP1/wwl/datafile/asm01.dbf' for'+ASMGROUP1/wwl/datafile/asm.270.780300769';
Diskgroup altered.
4.3 删除别名
SQL> alter diskgroup ASMGROUP1 dropalias '+ASMGROUP1/wwl/datafile/asm01.dbf' for'+ASMGROUP1/wwl/datafile/asm.270.780300769';
Diskgroup altered.
无论是添加、删除或是修改别名，对原文件路径均不会有影响。
五、 目录及目录文件管理
5.1 创建目录
SQL> alter diskgroup ASMGROUP1 add directory '+ASMGROUP1/WWL1';
Diskgroupaltered.
5.2 修改目录
SQL> alterdiskgroup ASMGROUP1 rename directory '+ASMGROUP1/WWL1' to '+ASMGROUP1/WWL2';
Diskgroupaltered.
5.3 删除目录
SQL> alter diskgroup ASMGROUP1 drop directory '+ASMGROUP1/WWL2';
Diskgroupaltered.
六、 手动平衡磁盘组
一般情况下ASM都会自动对其下的磁盘组进行平衡，不过ORACLE也提供了手动平衡磁盘组的方式，通过alter diskgroup ... power 语句。前面提到过磁盘组的平衡度有0到11多个级别，默认是按照ASM_POWER_LIMIT初始化参数中设置的值，手动平衡的话，设置的平衡度可以与初始化参数中并不相同，例如，设置磁盘组平衡度为5，语句如下：
SQL>alter diskgroup asmgroup1 rebalance power 5;
Diskgroup altered.
七、 通过ASMCMD工具管理ASM
[oracle@wwl ~]$ which asmcmd
/oracle/orahome/10.2.0/db_1/bin/asmcmd
[oracle@wwl ~]$ cd/oracle/orahome/10.2.0/db_1/bin/
ASMCMD> ls
ASMEXTERNAL/
ASMGROUP1/
ASMHIGH/
ASMNORMAL/
ASMCMD>
ASMCMD> help
asmcmd [-p] [command]
The environment variables ORACLE_HOME and ORACLE_SID determine the
instance to which the program connects, and ASMCMD establishes a
bequeath connection to it, in the same manner as a SQLPLUS / AS
SYSDBA. The user must be a memberof the SYSDBA group.
Specifying the -p option allows the current directory to be displayed
in the command prompt, like so:
ASMCMD [+DATAFILE/ORCL/CONTROLFILE] >
[command] specifies one of the following commands, along with its
parameters.
Type "help [command]" to get help on a specific ASMCMDcommand.
commands:
--------
cd：------------------------------------------进入下级目录或进入所需要的目录
du：------------------------------------------显示指定的ASM目录下ASM文件占用的所有磁盘空间
find：-----------------------------------------查找所需的文件
help：-----------------------------------------显示帮助信息
ls：---------------------------------------------列出ASM目录下的内容及其属性
lsct：-------------------------------------------列出当前ASM客户端的信息
lsdg：-------------------------------------------列出所有磁盘组及其属性
mkalias：--------------------------------------为系统生成的文件名创建别名
mkdir：----------------------------------------创建新目录
pwd：------------------------------------------显示当前目录路径
rm：--------------------------------------------删除ASM目录下的某个文件或文件夹
rmalias：--------------------------------------删除别名
ASMCMD>
要查看某个命令的相信通过在命令前添加help来查看，如下:
ASMCMD> help cd
cd <dir>
Change the current directory to <dir>.
ASMCMD> help du
du [-H] [dir]
Display total space used for files located recursively under [dir],
similar to "du -s" under UNIX; default is the currentdirectory. Two
values are returned, both in units of megabytes. The first value does
not take into account mirroring of the diskgroup while the second does.
For instance, if a file occupies 100 MB of space, then it actually
takes up 200 MB of space on a normal redundancy diskgroup and 300 MB
of space on a high redundancy diskgroup.
[dir] can also contain wildcards.
The -H flag suppresses the column headers from the output.
ASMCMD> help find
find [-t <type>] <dir> <pattern>
Find the absolute paths of all occurrences of <pattern> under<dir>.
<pattern> can be a directory and may include wildcards. <dir> may also
include wildcards. Note thatdirectory names in the results have the
"/" suffix to clarify their identity.
The -t option allows searching by file type. For instance, one can
search for all the control files at once. <type> must be one of the
valid values in V$ASM_FILE.TYPE.
ASMCMD>
八、 oracleasm工具的使用和语法介绍
[root@wwl ~]# oracleasm --help
Usage: oracleasm[--exec-path=<exec_path>] <command> [ <args> ]
oracleasm --exec-path
oracleasm -h
oracleasm -V
The basic oracleasm commands are:
configure Configure the OracleLinux ASMLib driver
init Load andinitialize the ASMLib driver
exit Stop the ASMLibdriver
scandisks Scan the systemfor Oracle ASMLib disks
status Display thestatus of the Oracle ASMLib driver
listdisks List known OracleASMLib disks
querydisk Determine if adisk belongs to Oracle ASMlib
createdisk Allocate a devicefor Oracle ASMLib use
deletedisk Return a deviceto the operating system
renamedisk Change the labelof an Oracle ASMlib disk
update-driver Download thelatest ASMLib driver
[root@wwl ~]#
九、 ASM相关视图（V$）和数据字典（X$）
ASM由于其高度的封装性，使得我们很难知道窥探其内部的原理。可以通过一下视图和数据字典来来查看ASM的信息。
相关视图和数据字典
| V$ASM_DISKGROUP |
X$KFGRP |
performs disk discovery and lists diskgroups |
| V$ASM_DISKGROUP_STAT |
X$KFGRP_STAT |
diskgroup stats without disk discovery |
| V$ASM_DISK |
X$KFDSK, X$KFKID |
performs disk discovery, lists disks and their usage metrics |
| V$ASM_DISK_STAT |
X$KFDSK_STAT, X$KFKID |
lists disks and their usage metrics |
| V$ASM_FILE |
X$KFFIL |
lists ASM files, including metadata/asmdisk files |
| V$ASM_ALIAS |
X$KFALS |
lists ASM aliases, files and directories |
| V$ASM_TEMPLATE |
X$KFTMTA |
lists the available templates and their properties |
| V$ASM_CLIENT |
X$KFNCL |
lists DB instances connected to ASM |
| V$ASM_OPERATION |
X$KFGMG |
lists rebalancing operations |
| N.A. |
X$KFKLIB |
available libraries, includes asmlib path |
| N.A. |
X$KFDPARTNER |
lists disk-to-partner relationships |
| N.A. |
X$KFFXP |
extent map table for all ASM files |
| N.A. |
X$KFDAT |
extent list for all ASM disks |
| N.A. |
X$KFBH |
describes the ASM cache (buffer cache of ASM in blocks of 4K (_asm_blksize) |
| N.A. |
X$KFCCE |
a linked list of ASM blocks. to be further investigated |
This list isobtained querying v$fixed_view_definitionwhere view_name like '%ASM%' whichexposes all the v$ and gv$ views with theirdefinition. Fixed tables are exposedby querying v$fixed_table where name like'x$kf%' (ASM fixed tables use the'X$KF' prefix).
SQL>select* fromv$fixed_view_definition whereview_name like '%ASM%';
SQL>select* from sys.v$fixed_tablewhere name like 'X$KF%' ;
十、 ASM常见的错误处理
错误一、
ORA-15097：cannotSHUTDOWN ASM instance with connected RDBMS instance
解决办法：
发生这个问题，唯一的一个原因就是Oracle实例没有关闭，或ORACLE实例正在关闭或处于挂起状态，导致ASM实例无法关闭，解决办法，关闭RDBMS实例后再关闭ASM实例。
错误二、
[root@wwl ~]# /etc/init.d/oracleasm createdisk VOL3 /dev/sdd
Marking disk "VOL3" as an ASM disk: [FAILED]
报这个错的原因在于磁盘为分区导致。在创建ASM的之前必须线将磁盘分区，但不能格式化，后执行创建就不会有问题了。
十一、 ASM 扩展性
- 最多支持63个磁盘组；
- 最多支持10000个磁盘；
- 最大支持4pb/磁盘；
- 最大支持40 exabyte/ASM存储；
- 最大支持1百W个文件/磁盘组；
- 外部冗余时单个文件最大35tb，标准冗余时单个文件最大5.8tb，高冗余度时单个文件最大3.9tb
十二、 ASM其它信息请参考如下连接：
http://docs.oracle.com/cd/E11882_01/server.112/e16102/asmfiles.htm
