Oracle_052_lesson_p5
Managing the ASM Instance管理ASM实例you should be able to:
1、Describe the benefits of using ASM
2、Manage the ASM instance
3、Create and drop ASM disk groups
4、Extend ASM disk groups
5、Retrieve ASM metadata by using various utilities
ASM：内存+进程
sqlplus/as sysasm;
v$asm_disk;
v$asm_diskgroup;
shared pool：元数据信息
large pool ：大池，并行操作的
asm cache： 重平衡，（值最小1，最大11，越大重平衡越快）
free memory： 空闲内存
ASM实例初始化参数
The ASM instance uses a small subset of the parameters that an Oracle Database instance uses.
[INSTANCE_TYPE = ASM
ASM_POWER_LIMIT = 1
ASM_DISKSTRING = '/dev/sda1','/dev/sdb*'
ASM_DISKGROUPS = DATA2, FRA
ASM_PREFERRED_READ_FAILURE_GROUPS = DATA.FailGroup2
DIAGNOSTIC_DEST = /u01/app/oracle
LARGE_POOL_SIZE = 12M
REMOTE_LOGIN_PASSWORDFILE = EXCLUSIVE]
SQL> showparameterspfile;
SQL>showparameterinstance_type;
ASM Instance: Dynamic Performance ViewsASM动态性能视图
ASM只有动态性能视图，文件是保存在OS的$ORACLE_HOME/dbs/orapw+asm中的
The ASM instance hosts memory-based metadata tables presented as dynamic performance views.
Accessed by ASM utilities to retrieve metadata-only information using the SQL language
Contains many dedicated ASM-related views such as:
V$ASM_ALIAS V$ASM_ATTRIBUTE V$ASM_CLIENT
V$ASM_DISK V$ASM_DISK_IOSTAT V$ASM_DISK_STAT
V$ASM_DISKGROUP V$ASM_DISKGROUP_STAT V$ASM_FILE
V$ASM_OPERATION V$ASM_TEMPLATE
先关DB，再关ASM。先开ASM，再开DB；
*Starting and Stopping ASM InstancesUsing SQLPlus用sqlplus起停ASM实例**
$ . oraenv
ORACLE_SID = ? +ASM
The Oracle base for ORACLE_HOME=/u01/app/oracle/product/11.2.0/grid is /u01/app/oracle
$ sqlplus / AS SYSASM
SQL*Plus:> Copyright (c) 1982, 2009, Oracle.All rights reserved.
Connected to an> SQL> startup
ASM instance started
Total System Global Area284565504 bytes
Fixed>
Variable> ASM Cache 25165824 bytes
ASM diskgroups mounted
ASM diskgroups volume enabled
SQL> shutdown abort
Starting and Stopping ASM Instances Using srvctl用srvctl起停ASM实例
$ . oraenv
ORACLE_SID = ? +ASM
The Oracle base for ORACLE_HOME=/u01/app/oracle/product/11.2.0/grid is /u01/app/oracle
$ srvctl start asm -o mount
$ srvctl stop asm -f
$ srvctl status asm
ASM is running on edrsr25p1
Starting and Stopping ASM Instances Using asmcmd用ASMCMD起停ASM实例
$ . oraenv
ORACLE_SID = ? +ASM
The Oracle base for ORACLE_HOME=/u01/app/oracle/product/11.2.0/grid is /u01/app/oracle
$ asmcmd
Connected to an> ASMCMD> startup
ASM instance started
Total System Global Area284565504 bytes
Fixed>
Variable> ASM Cache 25165824 bytes
ASM diskgroups mounted
ASM diskgroups volume enabled
ASMCMD> shutdown --abort
ASM instance shut down
Connected to an>
ASM disks are divided into allocation units (AU):
AU>
Default AU> Small enough to be cached by database and large enough for efficient sequential access
Allowable AU> 1, 2, 4, 8, 16, 32, or 64 MB
Large AUs may be useful in very large database (VLDB) scenarios or when using specialized storage hardware
ASM files:
Are a collection of ASM extents composed of AUs
Variable> Appear as normal files to the database kernel
Have file names that start with '+'
For example, +DATA/orcl/datafile/system.256.689832921
May be associated with an optional alias file name
For example, +DATA/dbfiles/mydb/system01.dbf
Are evenly distributed across disks in a disk group
Are mirrored according to the policies defined in the disk group
Striping Granularity条带化粒度
1、ASM separates striping for load balance and striping for latency:
Coarse-grain striping concatenates allocation units for load balancing.
数据文件粗粒度，以AU如1M为单元逐磁盘写入。
2、Fine-grain striping puts 128 KB stripe units across groups of allocation units to improve latency.
Disk group with 8 disks and external redundancy
Default AU> First 1 MB extent written as 128 KB stripes across 8 AUs
细粒度 ，以128K为单元逐磁盘写入，如控制文件、日志文件用细粒度。
管理ASM磁盘组
CREATE DISKGROUP
ALTER DISKGROUP
DROP DISKGROUP
Creating and Dropping Disk Groups Using SQLPlus
例：
$ . oraenv
ORACLE_SID = ? +ASM
The Oracle base for ORACLE_HOME=/u01/app/oracle/product/11.2.0/grid is /u01/app/oracle
$ sqlplus / AS SYSASM
SQLPlus:> Copyright (c) 1982, 2009, Oracle.All rights reserved.
..
SQL> CREATE DISKGROUP dgroupA NORMAL REDUNDANCY
FAILGROUP controller1 DISK
'/devices/A1' NAME diskA1> '/devices/A2',
FAILGROUP controller2 DISK
'/devices/B1',
'/devices/B2';
SQL> DROP DISKGROUP dgroupA INCLUDING CONTENTS;
例：
Remove a disk from dgroupA:
ALTER DISKGROUP dgroupA DROP DISK A5;
Add and drop a disk in a single command:增加和删除DISK用1条命令完成
ALTER DISKGROUP dgroupA DROP DISK A6
ADD FAILGROUP controller3 DISK '/dev/sdi1' NAME A9;
Add and drop a disk in a single command:
ALTER DISKGROUP dgroupA UNDROP DISKS;
例：
Adding Disks to Disk Groups
ALTER DISKGROUP dgroupA ADD DISK
'/dev/sde1' NAME A5,
'/dev/sdf1' NAME A6,
'/dev/sdg1' NAME A7,
'/dev/sdh1' NAME A8;
ALTER DISKGROUP dgroupA ADD DISK '/devices/A*';
ASMCMD> lsdsk
descv$asm_disk;
creatediskgroupdg_testexternal redurancydisk '/dev/sdi5'namei5;
ASMCMD>lsdg
dropdiskgroupdg_testincludingcontents;
ASM Disk Group CompatibilityASM磁盘组兼容性
Retrieving ASM Metadata 检索ASM元数据
SQL> SELECT f.type, f.redundancy, f.striped, f.modification_date, a.system_created, a.name FROM v$asm_alias a, v$asm_file f WHERE a.file_number = f.file_number and a.group_number = f.group_number and type='DATAFILE';
TYPE REDUNDSTRIPEMODIFICATSNAME
DATAFILEMIRRORCOARSE08-JUL-09YSYSTEM.256.689832921
DATAFILEMIRRORCOARSE08-JUL-09YSYSAUX.257.689832923
..
ASMCMD> ls -l +DATA/orcl/datafile
Type RedundStripedTime SysName
DATAFILEMIRRORCOARSE JUL 08 21:00:00Y SYSTEM.256.689832921
DATAFILEMIRRORCOARSE JUL 08 21:00:00Y SYSAUX.257.689832923
..
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