在Oracle Database 11gR2 中，asmcmd有了大量的改进和增强，即使11.2.0.2和11.2.0.1比较，也有很多不同。

在ASM元数据的备份与恢复方面，Oracle增加了两个命令：md_backup 和 md_restore。
md 是 metadata的缩写，这一工具极大的简化了ASM的元数据维护。

在asmcmd中，通过help md_backup可以看到详细的命令提示：

ASMCMD> help md_backup
md_backup

The md_backup command creates a backup file containing metadata
for one or more disk groups.
Volume and Oracle Automatic Storage Management Cluster File System
(Oracle ACFS) file system information is not backed up.

md_backup backup_file [-G diskgroup [,diskgroup,...]]

The options for the md_backup command are described below.

backup_file - Specifies the backup file in which you want to
store the metadata.
-G diskgroup - Specifies the disk group name of the disk group
that must be backed up

By default all the mounted disk groups are included in the backup file,
which is saved in the current working directory.

The first example shows the use of the backup command when you run it
without options. This example backs up all of the mounted disk groups
and creates the backup image in the current working directory. The
second example creates a backup of disk group DATA and FRA. The backup
that this example creates is saved in the /tmp/dgbackup20090714 file.

ASMCMD [+] > md_backup /tmp/dgbackup20090716
ASMCMD [+] > md_backup /tmp/dgbackup20090716 -G DATA,FRA
Disk group metadata to be backed up: DATA
Disk group metadata to be backed up: FRA
Current alias directory path: ASM/ASMPARAMETERFILE
Current alias directory path: ORCL/DATAFILE
Current alias directory path: ORCL/TEMPFILE
Current alias directory path: ORCL/CONTROLFILE
Current alias directory path: ORCL/PARAMETERFILE
Current alias directory path: ASM
Current alias directory path: ORCL/ONLINELOG
Current alias directory path: ORCL
Current alias directory path: ORCL/CONTROLFILE
Current alias directory path: ORCL/ARCHIVELOG/2009_07_13
Current alias directory path: ORCL/BACKUPSET/2009_07_14
Current alias directory path: ORCL/ARCHIVELOG/2009_07_14
Current alias directory path: ORCL
Current alias directory path: ORCL/DATAFILE
Current alias directory path: ORCL/ARCHIVELOG
Current alias directory path: ORCL/BACKUPSET
Current alias directory path: ORCL/ONLINELOG

现在backup_file是一个需要强制制定的参数，以下命令备份了ASM中所有的磁盘组元数据：

ASMCMD> md_backup /tmp/oradgbackup20110322
Disk group metadata to be backed up: ACFSG
Disk group metadata to be backed up: CRSDG
Disk group metadata to be backed up: ORADG
Current alias directory path: EYGLE/ONLINELOG
Current alias directory path: EYGLE
Current alias directory path: EYGLE/CONTROLFILE
Current alias directory path: ASM
Current alias directory path: EYGLE/PARAMETERFILE
Current alias directory path: EYGLE/CONTROLFILE
Current alias directory path: EYGLE/TEMPFILE
Current alias directory path: EYGLE/DATAFILE
Current alias directory path: EYGLE
Current alias directory path: EYGLE/ONLINELOG
Current alias directory path: ASM/ASMPARAMETERFILE

也可以制定备份特定的磁盘组信息：

ASMCMD> md_backup /tmp/oradgbackup20110323 -G ORADG
Disk group metadata to be backed up: ORADG

备份以文本格式记录了磁盘组的参数信息：

[grid@enmou1 ~]$ more /tmp/oradgbackup20110323
@diskgroup_set = (
{
'ATTRINFO' => {
'_._DIRVERSION' => '11.2.0.0.0',
'COMPATIBLE.ASM' => '11.2.0.0.0',
'COMPATIBLE.RDBMS' => '10.1.0.0.0'
},
'DISKSINFO' => {
'VOL3' => {
'VOL3' => {
'TOTAL_MB' => '9687',
'FAILGROUP' => 'VOL3',
'NAME' => 'VOL3',
'DGNAME' => 'ORADG',
'PATH' => 'ORCL:VOL3'
}
}
},
'DGINFO' => {
'DGTORESTORE' => 0,
'DGCOMPAT' => '11.2.0.0.0',
'DGNAME' => 'ORADG',
'DGDBCOMPAT' => '10.1.0.0.0',
'DGTYPE' => 'EXTERN',
'DGAUSZ' => '1048576'
},
'ALIASINFO' => {},
'TEMPLATEINFO' => {
'6' => {
'DGNAME' => 'ORADG',
'STRIPE' => 'COARSE',
'TEMPNAME' => 'ONLINELOG',
'REDUNDANCY' => 'UNPROT',
'SYSTEM' => 'Y'
},
'11' => {
'DGNAME' => 'ORADG',
'STRIPE' => 'COARSE',
'TEMPNAME' => 'AUTOBACKUP',
'REDUNDANCY' => 'UNPROT',
'SYSTEM' => 'Y'
},
'3' => {
'DGNAME' => 'ORADG',
'STRIPE' => 'FINE',
'TEMPNAME' => 'CONTROLFILE',
'REDUNDANCY' => 'UNPROT',
'SYSTEM' => 'Y'
},
'7' => {
'DGNAME' => 'ORADG',
'STRIPE' => 'COARSE',
'TEMPNAME' => 'DATAGUARDCONFIG',
'REDUNDANCY' => 'UNPROT',
'SYSTEM' => 'Y'
},
'9' => {
'DGNAME' => 'ORADG',
'STRIPE' => 'COARSE',
'TEMPNAME' => 'CHANGETRACKING',
'REDUNDANCY' => 'UNPROT',
'SYSTEM' => 'Y'
},
'12' => {
'DGNAME' => 'ORADG',
'STRIPE' => 'COARSE',
'TEMPNAME' => 'BACKUPSET',
'REDUNDANCY' => 'UNPROT',
'SYSTEM' => 'Y'
},
'2' => {
'DGNAME' => 'ORADG',
'STRIPE' => 'COARSE',
'TEMPNAME' => 'DUMPSET',
'REDUNDANCY' => 'UNPROT',
'SYSTEM' => 'Y'
},
'14' => {
'DGNAME' => 'ORADG',
'STRIPE' => 'COARSE',
'TEMPNAME' => 'DATAFILE',
'REDUNDANCY' => 'UNPROT',
'SYSTEM' => 'Y'
},
'15' => {
'DGNAME' => 'ORADG',
'STRIPE' => 'COARSE',
'TEMPNAME' => 'ASMPARAMETERFILE',
'REDUNDANCY' => 'UNPROT',
'SYSTEM' => 'Y'
},
'8' => {
'DGNAME' => 'ORADG',
'STRIPE' => 'COARSE',
'TEMPNAME' => 'FLASHBACK',
'REDUNDANCY' => 'UNPROT',
'SYSTEM' => 'Y'
},
'4' => {
'DGNAME' => 'ORADG',
'STRIPE' => 'COARSE',
'TEMPNAME' => 'FLASHFILE',
'REDUNDANCY' => 'UNPROT',
'SYSTEM' => 'Y'
},
'1' => {
'DGNAME' => 'ORADG',
'STRIPE' => 'COARSE',
'TEMPNAME' => 'OCRFILE',
'REDUNDANCY' => 'UNPROT',
'SYSTEM' => 'Y'
},
'0' => {
'DGNAME' => 'ORADG',
'STRIPE' => 'COARSE',
'TEMPNAME' => 'PARAMETERFILE',
'REDUNDANCY' => 'UNPROT',
'SYSTEM' => 'Y'
},
'10' => {
'DGNAME' => 'ORADG',
'STRIPE' => 'COARSE',
'TEMPNAME' => 'XTRANSPORT',
'REDUNDANCY' => 'UNPROT',
'SYSTEM' => 'Y'
},
'13' => {
'DGNAME' => 'ORADG',
'STRIPE' => 'COARSE',
'TEMPNAME' => 'TEMPFILE',
'REDUNDANCY' => 'UNPROT',
'SYSTEM' => 'Y'
},
'5' => {
'DGNAME' => 'ORADG',
'STRIPE' => 'COARSE',
'TEMPNAME' => 'ARCHIVELOG',
'REDUNDANCY' => 'UNPROT',
'SYSTEM' => 'Y'
}
}
}
);

通过这些信息，就可以在磁盘组损坏时，快速恢复ASM的元数据。
恢复在磁盘组可用状态下不允许执行：

ASMCMD> md_restore --full -G oradg /tmp/oradgbackup20110323
Current Diskgroup metadata being restored: ORADG
ASMCMD-09352: CREATE DISKGROUP failed
ORA-15018: diskgroup cannot be created
ORA-15030: diskgroup name "ORADG" is in use by another diskgroup (DBD ERROR: OCIStmtExecute)

以下是在DROP了ORADG之后，执行恢复的全过程，恢复完成以后，磁盘组被创建，模板信息被还原：

ASMCMD> md_restore --full -G oradg /tmp/oradgbackup20110323
Current Diskgroup metadata being restored: ORADG
Diskgroup ORADG created!
System template ONLINELOG modified!
System template AUTOBACKUP modified!
System template CONTROLFILE modified!
System template DATAGUARDCONFIG modified!
System template CHANGETRACKING modified!
System template DUMPSET modified!
System template BACKUPSET modified!
System template ASMPARAMETERFILE modified!
System template DATAFILE modified!
System template FLASHBACK modified!
System template OCRFILE modified!
System template FLASHFILE modified!
System template PARAMETERFILE modified!
System template TEMPFILE modified!
System template XTRANSPORT modified!
System template ARCHIVELOG modified!

通过-S参数可以仅生成恢复脚本，不执行恢复动作：

ASMCMD> md_restore -S create_oradg.sql /tmp/oradgbackup20110323
Current Diskgroup metadata being restored: ORADG

以下是ORADG磁盘组恢复时执行的命令：

[grid@enmou1 ~]$ more create_oradg.sql
create diskgroup ORADG EXTERNAL redundancy disk 'ORCL:VOL3' name VOL3 size 9687M attribute 'compatible.asm' = '11.2.0.0.0', 'compatible.r
dbms' = '10.1.0.0.0';
alter diskgroup /*ASMCMD AMBR*/ORADG set attribute '_._DIRVERSION' = '11.2.0.0.0';
alter diskgroup /*ASMCMD AMBR*/ORADG alter template ONLINELOG attributes (UNPROTECTED COARSE);
alter diskgroup /*ASMCMD AMBR*/ORADG alter template AUTOBACKUP attributes (UNPROTECTED COARSE);
alter diskgroup /*ASMCMD AMBR*/ORADG alter template CONTROLFILE attributes (UNPROTECTED FINE);
alter diskgroup /*ASMCMD AMBR*/ORADG alter template DATAGUARDCONFIG attributes (UNPROTECTED COARSE);
alter diskgroup /*ASMCMD AMBR*/ORADG alter template CHANGETRACKING attributes (UNPROTECTED COARSE);
alter diskgroup /*ASMCMD AMBR*/ORADG alter template DUMPSET attributes (UNPROTECTED COARSE);
alter diskgroup /*ASMCMD AMBR*/ORADG alter template BACKUPSET attributes (UNPROTECTED COARSE);
alter diskgroup /*ASMCMD AMBR*/ORADG alter template ASMPARAMETERFILE attributes (UNPROTECTED COARSE);
alter diskgroup /*ASMCMD AMBR*/ORADG alter template DATAFILE attributes (UNPROTECTED COARSE);
alter diskgroup /*ASMCMD AMBR*/ORADG alter template FLASHBACK attributes (UNPROTECTED COARSE);
alter diskgroup /*ASMCMD AMBR*/ORADG alter template OCRFILE attributes (UNPROTECTED COARSE);
alter diskgroup /*ASMCMD AMBR*/ORADG alter template FLASHFILE attributes (UNPROTECTED COARSE);
alter diskgroup /*ASMCMD AMBR*/ORADG alter template PARAMETERFILE attributes (UNPROTECTED COARSE);
alter diskgroup /*ASMCMD AMBR*/ORADG alter template TEMPFILE attributes (UNPROTECTED COARSE);
alter diskgroup /*ASMCMD AMBR*/ORADG alter template XTRANSPORT attributes (UNPROTECTED COARSE);
alter diskgroup /*ASMCMD AMBR*/ORADG alter template ARCHIVELOG attributes (UNPROTECTED COARSE);

ASMCMD的新增命令极多，以下是命令列表：

ASMCMD> help

asmcmd [-V] [-v <errors|warnings|normal|info|debug>] [--privilege <sysasm|sysDBA>] [-p] [command]
asmcmd_no_conn_str

Starts asmcmd or executes the command

asmcmd [-V] [-v <errors|warnings|normal|info|debug>] [--privilege <sysasm|sysdba>] [-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
SYSASM. The user must be a member of the OSASM group.

Specifying the -V option prints the asmcmd version number and
exits immediately.

Specifying the -v option prints extra information that can help
advanced users diagnose problems.

Specify the --privilege option to choose the type of connection. There are
only two possibilities: connecting as SYSASM or as SYSDBA.
The default value if this option is unspecified is SYSASM.

Specifying the -p option allows the current directory to be displayed
in the command prompt, like so:

ASMCMD [+DATA/ORCL/CONTROLFILE] >

[command] specifies one of the following commands, along with its
parameters.

Type "help [command]" to get help on a specific ASMCMD command.';

commands:
--------

md_backup, md_restore

lsattr, setattr

cd, cp, du, find, help, ls, lsct, lsdg, lsof, mkalias
mkdir, pwd, rm, rmalias

chdg, chkdg, dropdg, iostat, lsdsk, lsod, mkdg, mount
offline, online, rebal, remap, umount

dsget, dsset, lsop, shutdown, spbackup, spcopy, spget
spmove, spset, startup

chtmpl, lstmpl, mktmpl, rmtmpl

chgrp, chmod, chown, groups, grpmod, lsgrp, lspwusr, lsusr
mkgrp, mkusr, orapwusr, passwd, rmgrp, rmusr

volcreate, voldelete, voldisable, volenable, volinfo
volresize, volset, volstat