月份：2016年12月

对于Oracle 11.2.0.4及以后的数据库版本可以通过AWR报告来计算数据库的IOPS与吞吐量。在AWR报告中描述关于IOPS与吞吐量相关信息有以下三个不同的部分:
.Instance Activity Stats
.IO Profile(从11gr2开始)
.Load Profile

Instance Activity Stats
.IOPS(每秒I/O读写操作次数)–它是指每秒物理读取I/O请求总次数与每秒物理写I/O请求
总次数之和。
.吞吐量–它是指物理读取总字节数与物理写总字节数之和。

上图中所显示的信息如下:
IOPS=每秒物理读取I/O请求总次数 +每秒物理写I/O请求总次数
=47.13+71.27
=118.4
吞吐量=物理读取总字节数+物理写总字节数
=7819646464+15314800128
=23134446592 bytes
=18.3 GB

IO Profile
.IOPS:Total Requests(这个值是从Instance Avtivity Stats部分计算出来的每秒物理读取
I/O总次数与每秒物理写I/O总次数之和）
吞吐量/每秒:Total(MB)(这个值是指每秒物理读取总字节数与每秒物理写总字节数之和)

IOPS/每秒=每秒物理读取I/O总次数+每秒物理写I/O总次数
=47.1+71.3
=118.4
吞吐量/每秒=每秒物理读取总字节数+每秒物理写总字节数
=1+2 MB
=3.1 MB

Load Profile
Load Profile中的信息是IO Profile的一个子集

physical read IO requests
它是指应用程序活动所执行的读取请求次数(主要指buffer cache与direct load operation)，每次请求读取一个或多个数据块。它是”physical read total IO requests”统计信息的一个子集。

physical read total IO requests
它是指所有实例活动包括应用程序，备份与恢复，以及其它工具的读取请求次数，每次请求读取一个或多个数据块。它与”physical read total multi block requests”之间的差别就是，它代表单块读请求的总次数。

ASM Rebalance
使用传统逻辑卷管理器，扩展或收缩条带化的文件系统通常是很困难的。使用ASM，这些磁盘改变现 在调用重新分布(rebalance)可以无逢操作来条带数据。另外，这些操作可以联机执行。存储配置的任何改变–增加，删除或重设置磁盘大小，都会触发rebalance操作。ASM不会动态的围绕 着”host areas”或”hot extents”进行移动。因为ASM跨所有磁盘与数据库buffer cache分布区，阻止 small chunks of data出现在磁盘的host areas，完全消除了host disks或extents。

Rebalance Operation
rebalance operation跨磁盘组中的所有磁盘总是对文件区与空间使用提供了一种均匀分布。对每个 文件执行rebalance操作可以确保每个文件跨所有磁盘均匀分布。最关键的是ASM保证了I/O负载平衡 。ASM后台进程，RBAL管理rebalance操作。RBAL进程检查每个文件区映射，基于新的存储配置区会均 匀分布。例如，有块八磁盘的一个磁盘组，一个数据文件有40个区(每个磁盘将会有五个区)，当向磁 盘组增加两块大小一样的磁盘后，数据文件会跨10块磁盘执行rebalance与分布，每个磁盘只包含四 个区。只需要移动8个区就可以完成rebalance操作–，完全重新分布区是不必要，只需要移动最小数 量的区就可以达到均匀分布。

磁盘大小与文件大小是影响rebalance的权重因素。一个大的磁盘将消耗更多的区。ASM rebalance操作有以下工作流程:
1.对ASM实例，DBA向磁盘组增加磁盘或从磁盘组中删除磁盘。

2.调用RBAL进程来创建一个rebalance计划，然后开始调度重新分布操作。

3.RBAL计算评估时间与执行任务所需要的工作，然后给ASM rebalance(ARBx)进程发送处理请求。调 用的ARBx进程的数量直接由init.ora参数asm_power_limit或在add ,drop或rebalance命令所指定的 power level所决定。

4.持续操作目录(COD)会被更新来反映一个rebalance活动。COD在influx rebalance失败时很重要。 恢复实例时对于rebalance与重启将会看到一个显著的COD条目。

5.RBAL对ARBs分布计划。一般,RBAL对每个文件生成一个计划，然而，大文件可能被多个ARBs分解。

6.ARBx对这些区执行rebalance。每个区会被锁定，重定位与解锁。当一个区被锁定时可以被读取。 写也仍然可以执行，但可能需要对新位置重新执行。这个操作会在v$asm_operation中显示了REBAL。

测试过程如下:
1.查看asm_power_limit参数设置

SQL> show parameter asm_power

NAME                                 TYPE                   VALUE
------------------------------------ ----------------------  ------------------------------
asm_power_limit                      integer                1

2.向磁盘组datadg增加磁盘

SQL> alter diskgroup datadg add disk '/dev/raw/raw5'

Diskgroup altered.

3.查看alert_+ASM1.log

SQL> alter diskgroup datadg add disk '/dev/raw/raw5'
Thu Dec 01 15:39:18 CST 2016
NOTE: reconfiguration of group 1/0x489bd291 (DATADG), full=1
Thu Dec 01 15:39:18 CST 2016
NOTE: initializing header on grp 1 disk DATADG_0001
NOTE: cache opening disk 1 of grp 1: DATADG_0001 path:/dev/raw/raw5
NOTE: requesting all-instance disk validation for group=1
Thu Dec 01 15:39:18 CST 2016
NOTE: disk validation pending for group 1/0x489bd291 (DATADG)
SUCCESS: validated disks for 1/0x489bd291 (DATADG)
Thu Dec 01 15:39:21 CST 2016
NOTE: PST update: grp = 1
NOTE: requesting all-instance membership refresh for group=1
Thu Dec 01 15:39:21 CST 2016
NOTE: membership refresh pending for group 1/0x489bd291 (DATADG)
SUCCESS: refreshed membership for 1/0x489bd291 (DATADG)
Thu Dec 01 15:39:27 CST 2016
NOTE: starting rebalance of group 1/0x489bd291 (DATADG) at power 1
Starting background process ARB0
ARB0 started with pid=19, OS id=21560
Thu Dec 01 15:39:27 CST 2016
NOTE: assigning ARB0 to group 1/0x489bd291 (DATADG)
Thu Dec 01 15:39:31 CST 2016
NOTE: X->S down convert bast on F1B3 bastCount=2
NOTE: X->S down convert bast on F1B3 bastCount=3
NOTE: X->S down convert bast on F1B3 bastCount=4
NOTE: X->S down convert bast on F1B3 bastCount=5
NOTE: X->S down convert bast on F1B3 bastCount=6
NOTE: X->S down convert bast on F1B3 bastCount=7
Thu Dec 01 15:40:34 CST 2016
NOTE: stopping process ARB0
Thu Dec 01 15:40:37 CST 2016
SUCCESS: rebalance completed for group 1/0x489bd291 (DATADG)
Thu Dec 01 15:40:37 CST 2016
SUCCESS: rebalance completed for group 1/0x489bd291 (DATADG)
NOTE: PST update: grp = 1
NOTE: PST update: grp = 1
Thu Dec 01 15:48:29 CST 2016

当使用缺省参数值asm_power_limit=1，向磁盘组增加一块磁盘执行rebalance操作花了将近9分钟（ 从2016-12-01 15:39:12开始到2016-12-01 15:48:29完成)

手动指定rebalance power操作如下:
1.向磁盘组datadg增加磁盘

SQL> alter diskgroup datadg add disk '/dev/raw/raw6';

Diskgroup altered.

2.查看alert_+ASM1.log

SQL> alter diskgroup datadg add disk '/dev/raw/raw6' rebalance power 4
Thu Dec 01 15:48:30 CST 2016
NOTE: reconfiguration of group 1/0x489bd291 (DATADG), full=1
Thu Dec 01 15:48:30 CST 2016
NOTE: initializing header on grp 1 disk DATADG_0002
NOTE: cache opening disk 2 of grp 1: DATADG_0002 path:/dev/raw/raw6
NOTE: requesting all-instance disk validation for group=1
Thu Dec 01 15:48:30 CST 2016
NOTE: disk validation pending for group 1/0x489bd291 (DATADG)
SUCCESS: validated disks for 1/0x489bd291 (DATADG)
Thu Dec 01 15:48:33 CST 2016
NOTE: PST update: grp = 1
NOTE: requesting all-instance membership refresh for group=1
Thu Dec 01 15:48:33 CST 2016
NOTE: membership refresh pending for group 1/0x489bd291 (DATADG)
SUCCESS: refreshed membership for 1/0x489bd291 (DATADG)
Thu Dec 01 15:48:39 CST 2016
NOTE: starting rebalance of group 1/0x489bd291 (DATADG) at power 4
Starting background process ARB0
Starting background process ARB1
ARB0 started with pid=19, OS id=25110
Thu Dec 01 15:48:39 CST 2016
Starting background process ARB2
ARB1 started with pid=21, OS id=25114
Thu Dec 01 15:48:39 CST 2016
Starting background process ARB3
ARB2 started with pid=22, OS id=25119
Thu Dec 01 15:48:40 CST 2016
NOTE: assigning ARB0 to group 1/0x489bd291 (DATADG)
ARB3 started with pid=23, OS id=25121
Thu Dec 01 15:48:40 CST 2016
NOTE: assigning ARB1 to group 1/0x489bd291 (DATADG)
NOTE: assigning ARB2 to group 1/0x489bd291 (DATADG)
NOTE: assigning ARB3 to group 1/0x489bd291 (DATADG)
Thu Dec 01 15:48:47 CST 2016
NOTE: X->S down convert bast on F1B3 bastCount=8
NOTE: X->S down convert bast on F1B3 bastCount=9
NOTE: X->S down convert bast on F1B3 bastCount=10
NOTE: X->S down convert bast on F1B3 bastCount=11
NOTE: X->S down convert bast on F1B3 bastCount=12
NOTE: X->S down convert bast on F1B3 bastCount=13
Thu Dec 01 15:49:21 CST 2016
NOTE: stopping process ARB1
NOTE: stopping process ARB2
NOTE: stopping process ARB0
NOTE: stopping process ARB3
Thu Dec 01 15:49:25 CST 2016
SUCCESS: rebalance completed for group 1/0x489bd291 (DATADG)
Thu Dec 01 15:49:25 CST 2016
SUCCESS: rebalance completed for group 1/0x489bd291 (DATADG)
NOTE: PST update: grp = 1
NOTE: PST update: grp = 1

手动指定rebalance power=4，向磁盘组增加一块磁盘执行rebalance操作花了将近1分钟（从2016- 12-01 15:48:30开始到2016-12-01 15:49:25完成)。

对于如何设置rebalance进程数可以参考文档《Oracle Sun Database Machine High Availability Best Practices (Doc ID 1069521.1)》

对于rebalance操作所调用的每个ARB进程将会创建一个ARB跟踪文件。这个ARB跟踪文件可以在DIAG目 录上的子目录中找到。跟踪文件的内容类似如下:

/u01/app/oracle/admin/+ASM/bdump/+asm1_arb0_25110.trc
Oracle Database 10g Enterprise Edition Release 10.2.0.5.0 - Production
With the Partitioning, Real Application Clusters, OLAP, Data Mining
and Real Application Testing options
ORACLE_HOME = /u01/app/oracle/product/10.2.0/db
System name:	Linux
Node name:	jyrac3
Release:	2.6.18-164.el5PAE
Version:	#1 SMP Tue Aug 18 15:59:11 EDT 2009
Machine:	i686
Instance name: +ASM1
Redo thread mounted by this instance: 0 
Oracle process number: 19
Unix process pid: 25110, image: oracle@jyrac3 (ARB0)

*** SERVICE NAME:() 2016-12-01 15:48:40.086
*** SESSION ID:(34.29) 2016-12-01 15:48:40.086
ARB0 relocating file +DATADG.2.1 (1 entries)
ARB0 relocating file +DATADG.256.926895041 (34 entries)
*** 2016-12-01 15:48:58.473
ARB0 relocating file +DATADG.257.926895043 (1 entries)
ARB0 relocating file +DATADG.258.926895047 (16 entries)
ARB0 relocating file +DATADG.259.926895047 (1 entries)
ARB0 relocating file +DATADG.260.926895413 (6 entries)
ARB0 relocating file +DATADG.261.926895419 (18 entries)
*** 2016-12-01 15:49:08.569
ARB0 relocating file +DATADG.262.926895423 (19 entries)
ARB0 relocating file +DATADG.263.926895443 (8 entries)
ARB0 relocating file +DATADG.264.926895475 (33 entries)

在开始执行rebalance操作之后修改asm rebalance power
rebalance power的缺省值由asm_power_limit参数所指定为1。rebalance power的值越高， rebalance操作可能完成的越快。较低的rebalance power值可能造成rebalance操作时间很长，但是 消耗较少的CPU与I/O资源。

power的取值范围从0到11，当为0时停止rebalance，当为11时最快。从oracle 11.2.0.2开始，如果 磁盘组属性compatible.asm被设置为11.2.0.2或更高的版本，那么它的取值范围为0到1024。可以动 态调用这个参数，然而调整asm_power_limit只会影响之后的rebalance操作。不影响正在执行的 rebalance操作。为了在开始执行rebalance操作之后修改power，可以执行如下命令:
alter diskgroup rebalance [power n];

测试情况如下:

SQL> show parameter asm_power_limit

NAME                                 TYPE                   VALUE
------------------------------------ ----------------------  ------------------------------
asm_power_limit                      integer                1


SQL> alter diskgroup datadg add disk '/dev/raw/raw5','/dev/raw/raw6';

Diskgroup altered.

SQL> select * from v$asm_operation;

GROUP_NUMBER OPERATION  STATE         POWER     ACTUAL      SOFAR   EST_WORK   EST_RATE  EST_MINUTES
------------ ---------- -------- ---------- ---------- ---------- ---------- ----------  -----------
           1 REBAL      RUN               1          1          2        772         60           12

查看alert_+ASM1.log

Thu Dec 01 16:47:43 CST 2016
NOTE: reconfiguration of group 1/0x489bd291 (DATADG), full=1
Thu Dec 01 16:47:43 CST 2016
NOTE: initializing header on grp 1 disk DATADG_0001
NOTE: initializing header on grp 1 disk DATADG_0002
NOTE: cache opening disk 1 of grp 1: DATADG_0001 path:/dev/raw/raw5
NOTE: cache opening disk 2 of grp 1: DATADG_0002 path:/dev/raw/raw6
NOTE: requesting all-instance disk validation for group=1
Thu Dec 01 16:47:43 CST 2016
NOTE: disk validation pending for group 1/0x489bd291 (DATADG)
SUCCESS: validated disks for 1/0x489bd291 (DATADG)
Thu Dec 01 16:47:47 CST 2016
NOTE: PST update: grp = 1
NOTE: requesting all-instance membership refresh for group=1
Thu Dec 01 16:47:48 CST 2016
NOTE: membership refresh pending for group 1/0x489bd291 (DATADG)
SUCCESS: refreshed membership for 1/0x489bd291 (DATADG)
Thu Dec 01 16:47:54 CST 2016
NOTE: starting rebalance of group 1/0x489bd291 (DATADG) at power 1
Starting background process ARB0
ARB0 started with pid=18, OS id=16007
Thu Dec 01 16:47:54 CST 2016
NOTE: assigning ARB0 to group 1/0x489bd291 (DATADG)
Thu Dec 01 16:48:00 CST 2016
NOTE: X->S down convert bast on F1B3 bastCount=27
NOTE: X->S down convert bast on F1B3 bastCount=28
NOTE: X->S down convert bast on F1B3 bastCount=29
NOTE: X->S down convert bast on F1B3 bastCount=30
NOTE: X->S down convert bast on F1B3 bastCount=31
NOTE: X->S down convert bast on F1B3 bastCount=32
NOTE: X->S down convert bast on F1B3 bastCount=33
NOTE: X->S down convert bast on F1B3 bastCount=34
NOTE: X->S down convert bast on F1B3 bastCount=35
NOTE: X->S down convert bast on F1B3 bastCount=36
Thu Dec 01 16:48:09 CST 2016

从信息Starting background process ARB0，可知只启动了一个ARB进程，因为asm_power_limit参数为1

SQL> alter diskgroup datadg rebalance power 8;

Diskgroup altered.

查看alert_+ASM1.log

Thu Dec 01 16:48:09 CST 2016
ERROR: ORA-1013 thrown in ARB0 for group number 1
Thu Dec 01 16:48:09 CST 2016
Errors in file /u01/app/oracle/admin/+ASM/bdump/+asm1_arb0_16007.trc:
ORA-01013: user requested cancel of current operation
Thu Dec 01 16:48:09 CST 2016
NOTE: stopping process ARB0
Thu Dec 01 16:48:12 CST 2016
NOTE: rebalance interrupted for group 1/0x489bd291 (DATADG)
Thu Dec 01 16:48:12 CST 2016
NOTE: PST update: grp = 1
NOTE: requesting all-instance membership refresh for group=1
Thu Dec 01 16:48:12 CST 2016
NOTE: membership refresh pending for group 1/0x489bd291 (DATADG)
SUCCESS: refreshed membership for 1/0x489bd291 (DATADG)
Thu Dec 01 16:48:18 CST 2016
NOTE: starting rebalance of group 1/0x489bd291 (DATADG) at power 8
Starting background process ARB0
Starting background process ARB1
ARB0 started with pid=18, OS id=16133
Thu Dec 01 16:48:19 CST 2016
Starting background process ARB2
ARB1 started with pid=19, OS id=16135
Thu Dec 01 16:48:19 CST 2016
Starting background process ARB3
ARB2 started with pid=21, OS id=16142
Thu Dec 01 16:48:19 CST 2016
Starting background process ARB4
ARB3 started with pid=22, OS id=16144
Thu Dec 01 16:48:19 CST 2016
Starting background process ARB5
ARB4 started with pid=23, OS id=16146
Thu Dec 01 16:48:19 CST 2016
Starting background process ARB6
ARB5 started with pid=24, OS id=16148
Thu Dec 01 16:48:20 CST 2016
Starting background process ARB7
ARB6 started with pid=25, OS id=16150
Thu Dec 01 16:48:20 CST 2016
NOTE: assigning ARB0 to group 1/0x489bd291 (DATADG)
ARB7 started with pid=26, OS id=16157
Thu Dec 01 16:48:20 CST 2016
NOTE: assigning ARB1 to group 1/0x489bd291 (DATADG)
NOTE: assigning ARB2 to group 1/0x489bd291 (DATADG)
NOTE: assigning ARB3 to group 1/0x489bd291 (DATADG)
NOTE: assigning ARB4 to group 1/0x489bd291 (DATADG)
NOTE: assigning ARB5 to group 1/0x489bd291 (DATADG)
NOTE: assigning ARB6 to group 1/0x489bd291 (DATADG)
NOTE: assigning ARB7 to group 1/0x489bd291 (DATADG)
Thu Dec 01 16:48:48 CST 2016
NOTE: stopping process ARB5
NOTE: stopping process ARB2
NOTE: stopping process ARB7
NOTE: stopping process ARB1
NOTE: stopping process ARB6
Thu Dec 01 16:49:01 CST 2016
NOTE: stopping process ARB0
Thu Dec 01 16:49:11 CST 2016
NOTE: stopping process ARB4
NOTE: stopping process ARB3
Thu Dec 01 16:49:14 CST 2016
SUCCESS: rebalance completed for group 1/0x489bd291 (DATADG)
Thu Dec 01 16:49:14 CST 2016
SUCCESS: rebalance completed for group 1/0x489bd291 (DATADG)
NOTE: PST update: grp = 1
NOTE: PST update: grp = 1

从信息NOTE: stopping process ARB0，可知在执行alter diskgroup datadg rebalance power 8命 令后，终止了之前所启动的rebalance进程，后面启动了8个ARB进程来完成rebalance操作。

ASM分配单元
ASM分配空间以chunks为单位，叫作分配单元(AUs)。一个AU是最细粒度的分配–每个ASM磁盘都以相 同大小的AU进行划分。ASM 1MB条带大小对于Oracle数据库来说已经证明是最佳条带深度并且将会支 持最大I/O请求。这个最佳条带大小，再加上均匀分布磁盘组中的区与RDBMS中的buffer cache，防止热点。

对于VLDBs设置 Large AU Size
对于非常大的数据库(VLDBs)–例如，数据库大小为10TB与更大的来说，改变缺省AU大小是有意义的 。以下是对于VLDB改变缺省大小的优点:
.减小RDBMS实例中管理区映射的大小
.增加文件大小限制
.减小数据库打开的时间，因为VLDB通常有许多大的数据文件

增加AU大小可以提高oracle 10g打开大数据库的时间，也会减小区映射所消耗共享池的大小。使用 1MB AU与固定大小区，对于一个10TB数据库来说区映射的大小大约是90MB，在打开数据库时会被读取并被保存在内存中。使用16M AU，对于10TB数据库来说区映射大小减小为大约5.5MB。在Oracle 10g 中，一个文件整个区映射是在文件打开时从磁盘进行读取的。

Oracle 11g通过按需读取区映射显著的最小化了文件打开延迟问题。在Oracle 10g中，对于每个文件 的打开，完整的区映射需要构建并且从ASM实例发送给RDBMS实例。对于大文件，延长文件打开时间这 是不必要的。在oracle 11g中，在文件打开时只有区映射中的前60个区会被发送。剩下的以批量方式被发送到RDBMS。

在Oracle 11g中设置Large AU Size
对于Oracle 11g ASM系统，下面的create diskgroup命令可以被执行用来设置合适的AU大小:

SQL> CREATE DISKGROUP DATA DISK '/dev/raw/raw15', '/dev/raw/raw16',
'/dev/raw/raw17' ATTRIBUTE 'au_size' = '16M', 'compatible.asm' = '11.1'
'compatible.rdbms' = '11.1';

对Oracle 10g设置Large AU Size
在Oracle 10g中，ASM提供了两个隐藏参数(_asm_ausize,_asm_stripesize)来允许你使用16MB的AU大小来创建磁盘组并且对于1MB（代 替128K)有更好的细粒度条带。

SQL> set long 200
SQL> set linesize 200
SQL> select x.ksppinm NAME,y.ksppstvl value,x.ksppdesc describ
  2  from x$ksppi x, x$ksppcv y
  3  where x.inst_id=USERENV('Instance')
  4  and y.inst_id=USERENV('Instance')
  5  and x.indx=y.indx
  6  and x.ksppinm='_asm_stripesize';

NAME                           VALUE                DESCRIB
------------------------------ -------------------- ------------------------------
_asm_stripesize                131072               ASM file stripe size

SQL> select x.ksppinm NAME,y.ksppstvl value,x.ksppdesc describ
  2  from x$ksppi x, x$ksppcv y
  3  where x.inst_id=USERENV('Instance')
  4  and y.inst_id=USERENV('Instance')
  5  and x.indx=y.indx
  6  and x.ksppinm='_asm_ausize'
  7  ;

NAME                           VALUE                DESCRIB
------------------------------ -------------------- ------------------------------
_asm_ausize                    1048576              allocation unit size

AU参数只在创建磁盘组时才使用，而且在磁盘组创建之后现有磁盘组的AU大小是不会改变的。下面的例子使用16MB AU大小来创建一个磁盘组并且对所有数据库文件允许使用1MB的细粒度条带。

1.关闭ASM实例

oracle@jyrac3 ~]$ export ORACLE_SID=+ASM1
[oracle@jyrac3 ~]$ sqlplus / as sysdba

SQL*Plus: Release 10.2.0.5.0 - Production on Wed Nov 30 11:12:02 2016

Copyright (c) 1982, 2010, Oracle.  All Rights Reserved.


Connected to:
Oracle Database 10g Enterprise Edition Release 10.2.0.5.0 - Production
With the Partitioning, Real Application Clusters, OLAP, Data Mining
and Real Application Testing options

SQL> shutdown immediate
ASM diskgroups dismounted
ASM instance shutdown


oracle@jyrac4 ~]$ export ORACLE_SID=+ASM2
[oracle@jyrac4 ~]$ sqlplus / as sysdba

SQL*Plus: Release 10.2.0.5.0 - Production on Wed Nov 30 11:12:02 2016

Copyright (c) 1982, 2010, Oracle.  All Rights Reserved.


Connected to:
Oracle Database 10g Enterprise Edition Release 10.2.0.5.0 - Production
With the Partitioning, Real Application Clusters, OLAP, Data Mining
and Real Application Testing options

SQL> shutdown immediate
ASM diskgroups dismounted
ASM instance shutdown

2.编辑ASM实例的initSID.ora文件增加以下参数:

[oracle@jyrac3 dbs]$ vi init+ASM1.ora
...省略...
#ASM AU 16MB
_asm_ausize=16777216
#ASM fine grain stripesize 1MB
_asm_stripesize=1048576

[oracle@jyrac4 dbs]$ vi init+ASM2.ora
...省略...
#ASM AU 16MB
_asm_ausize=16777216
#ASM fine grain stripesize 1MB
_asm_stripesize=1048576

3.重新ASM实例。为了使用新参数生效ASM实例必须重启。在设置完隐藏参数并重启ASM实例，在这之 后创建的磁盘组将使用新的AU大小与细粒度条带大小。

SQL> col name for a20
SQL> col value for a20
SQL> col describ for a20
SQL> select x.ksppinm NAME,y.ksppstvl value,x.ksppdesc describ
  2  from x$ksppi x, x$ksppcv y
  3  where x.inst_id=USERENV('Instance')
  4  and y.inst_id=USERENV('Instance')
  5  and x.indx=y.indx
  6  and x.ksppinm='_asm_ausize';

NAME                 VALUE                DESCRIB
-------------------- -------------------- --------------------
_asm_ausize          16777216             allocation unit size

SQL> select x.ksppinm NAME,y.ksppstvl value,x.ksppdesc describ
from x$ksppi x, x$ksppcv y
  2    3  where x.inst_id=USERENV('Instance')
  4  and y.inst_id=USERENV('Instance')
  5  and x.indx=y.indx
  6  and x.ksppinm='_asm_stripesize';

NAME                 VALUE                DESCRIB
-------------------- -------------------- --------------------
_asm_stripesize      1048576              ASM file stripe size

4.创建磁盘组data_nrml

SQL> create diskgroup data_nrml  normal redundancy failgroup fg1 disk '/dev/raw/raw5'  failgroup fg2 disk '/dev/raw/raw6';

Diskgroup created.

5.查询v$asm_diskgroup_stat或v$asm_diskgroup中的allocation_unit_size来验证磁盘组data_nrml 的AU大小是否为16MB.

SQL> select name, allocation_unit_size from v$asm_diskgroup where name='DATA_NRML';

NAME                 ALLOCATION_UNIT_SIZE
-------------------- --------------------
DATA_NRML                        16777216

6.通过查询v$asm_template视图来查看磁盘组data_nrml的ASM文件模板，为了完成1MB的条带大小需 要将磁盘组中所要存储的所有文件类型的条带类型设置为FINE

SQL> select * from v$asm_template where group_number=2;

GROUP_NUMBER ENTRY_NUMBER REDUNDANCY   STRIPE       SY NAME
------------ ------------ ------------ ------------ -- --------------------
           2            0 MIRROR       COARSE       Y  PARAMETERFILE
           2            1 MIRROR       COARSE       Y  DUMPSET
           2            2 HIGH         FINE         Y  CONTROLFILE
           2            3 MIRROR       COARSE       Y  ARCHIVELOG
           2            4 MIRROR       FINE         Y  ONLINELOG
           2            5 MIRROR       COARSE       Y  DATAFILE
           2            6 MIRROR       COARSE       Y  TEMPFILE
           2            7 MIRROR       COARSE       Y  BACKUPSET
           2            8 MIRROR       COARSE       Y  AUTOBACKUP
           2            9 MIRROR       COARSE       Y  XTRANSPORT
           2           10 MIRROR       COARSE       Y  CHANGETRACKING
           2           11 MIRROR       FINE         Y  FLASHBACK
           2           12 MIRROR       COARSE       Y  DATAGUARDCONFIG

SQL> declare
  2  cursor jl is select * from v$asm_template where group_number=2 and STRIPE='COARSE';
  3  begin
  4      for r in jl loop
  5       execute immediate 'alter diskgroup data_nrml alter template '||r.name||'  attributes (fine)';
  6      end loop;
  7  end;
  8  /

PL/SQL procedure successfully completed.

SQL> select * from v$asm_template where group_number=2;

GROUP_NUMBER ENTRY_NUMBER REDUNDANCY   STRIPE       SY NAME
------------ ------------ ------------ ------------ -- --------------------
           2            0 MIRROR       FINE         Y  PARAMETERFILE
           2            1 MIRROR       FINE         Y  DUMPSET
           2            2 HIGH         FINE         Y  CONTROLFILE
           2            3 MIRROR       FINE         Y  ARCHIVELOG
           2            4 MIRROR       FINE         Y  ONLINELOG
           2            5 MIRROR       FINE         Y  DATAFILE
           2            6 MIRROR       FINE         Y  TEMPFILE
           2            7 MIRROR       FINE         Y  BACKUPSET
           2            8 MIRROR       FINE         Y  AUTOBACKUP
           2            9 MIRROR       FINE         Y  XTRANSPORT
           2           10 MIRROR       FINE         Y  CHANGETRACKING
           2           11 MIRROR       FINE         Y  FLASHBACK
           2           12 MIRROR       FINE         Y  DATAGUARDCONFIG

这种改变的目的是尽管使用大AU设置，仍然保持1MB的文件区分布。如果使用缺省的coarse条带，那 么将使用16MB进行条带。在Oracle 11g中当使用可变区大小就不需要执行这种改变。