Administering ASM Files and Directories

Administering ASM Files, Directories, and Templates

11g ASM is a volume manager and a file system for Oracle database files.

Objectives

• Use different client tools to access Automatic Storage Management (ASM) files
• Describe the format of a fully qualified ASM file name
• Explain how ASM files, directories, and aliases are created and managed
• Describe and manage disk group templates
  

Topics

1. Clients that connect directly to ASM include
   
2. How to migrate existing databases into ASM
   
3. Accessing ASM Files by Using RMAN
   
4. Accessing ASM Files by Using XML DB
5. Accessing ASM Files by Using DBMS_FILE_TRANSFER
   
6. Accessing ASM Files by Using ASMCMD
   
7. Fully Qualified ASM File Names
   
8. ASM File Creation
9. ASM Directories
10. Disk Group Templates
11. ASM Intelligent Data Placement
12. View ASM Aliases Files and Directories

Refer the links below:

Administering ASM Files, Directories, and Templates

View ASM Aliases-Files-and-Directories

View ASM Aliases, Files, and Directories

V$ASM_ALIAS contains a record for each system-generated file name, user-defined alias, and directory for every currently mounted disk group.

Use a hierarchical query on V$ASM_ALIAS to reconstruct the hierarchy of files, aliases, and directories in ASM. Join V$ASM_ALIAS with V$ASM_FILE to display additional file information, such as the file type. V$ASM_ALIAS is also commonly joined with V$ASM_DISKGROUP to display the disk group name.

The asmcmd ls -l command lists the contents of a directory:

ASMCMD> ls -l +DATA/RACDB/DATAFILE

Type Redund Striped Time Sys Name

DATAFILE MIRROR COARSE JUL 31 14:00:00 Y EXAMPLE.264.692926563

DATAFILE MIRROR COARSE JUL 31 14:00:00 Y SYSAUX.257.692926339

DATAFILE MIRROR COARSE JUL 31 14:00:00 Y SYSTEM.256.692926339

DATAFILE MIRROR COARSE JUL 31 14:00:00 Y UNDOTBS1.258.692926341

DATAFILE MIRROR COARSE JUL 31 14:00:00 Y UNDOTBS2.265.692926841

DATAFILE MIRROR COARSE JUL 31 14:00:00 Y USERS.259.692926341

The following query shows an example of how to reconstruct the ASM file hierarchy using V$ASM_ALIAS in combination with other V$ASM views:

SQL> SELECT CONCAT('+'||GNAME, SYS_CONNECT_BY_PATH(ANAME, '/'))
  2    FULL_PATH, SYSTEM_CREATED, ALIAS_DIRECTORY, FILE_TYPE
  3  FROM ( SELECT B.NAME GNAME, A.PARENT_INDEX PINDEX,
  4           A.NAME ANAME, A.REFERENCE_INDEX RINDEX,
  5           A.SYSTEM_CREATED, A.ALIAS_DIRECTORY,
  6           C.TYPE FILE_TYPE
  7         FROM V$ASM_ALIAS A, V$ASM_DISKGROUP B, V$ASM_FILE C
  8         WHERE A.GROUP_NUMBER = B.GROUP_NUMBER
  9               AND A.GROUP_NUMBER = C.GROUP_NUMBER(+)
 10               AND A.FILE_NUMBER = C.FILE_NUMBER(+)
 11               AND A.FILE_INCARNATION = C.INCARNATION(+)
 12       )
 13  START WITH (MOD(PINDEX, POWER(2, 24))) = 0
 14  CONNECT BY PRIOR RINDEX = PINDEX;

ASM Intelligent Data Placement

It is known that access to the data furthest from the spindle of a disk can be as much as 50% faster than for the data closest to the spindle. So placing frequently accessed data in the disk region furthest from the spindle will increase performance. This region is called the hot region and the region closest to the spindle, the cold region.

Some customers would never use the cold region of the disk nearest the spindle due to the increased latency. With Intelligent Data Placement, you can assign an ASM file to a disk region for best performance and use the lower performance region for less frequently accessed files. Using the disk region settings, you can ensure that frequently accessed data is placed on the outermost tracks (hot region). In addition, when files with similar access patterns are located physically close together, latency is reduced. Intelligent Data Placement also allows the placement of primary and mirror extents in different hot or cold regions.

Intelligent Data Placement settings can be specified for a file or in disk group templates. The disk region settings for a file can be modified after the file has been created. The disk region setting can improve I/O performance by placing more frequently accessed data in regions furthest from the spindle, while reducing your cost by increasing the usable space on a disk.

Guidelines for Intelligent Data Placement

Intelligent Data Placement works best for:

• Data files that are accessed at different rates
• Disk groups more than 50% full
• Disks with the geometry exposed to ASM (JBOD)

Intelligent Data Placement requires disk group attributes.

• COMPATIBLE.ASM = 11.2.0 or higher
• COMPATIBLE.RDBMS = 11.2.0 or higher

Assigning Files to Disk Regions

Create a file template:

ALTER DISKGROUP data ADD TEMPLATE datafile_hot

ATTRIBUTES ( HOT MIRRORHOT);

Alter the file attributes:

ALTER DISKGROUP data MODIFY FILE '+data/orcl/datafile/users.259.679156903'

ATTRIBUTES (COLD MIRRORCOLD);



Assigning Files to Disk Regions with Enterprise Manager






Monitoring Intelligent Data Placement

Performance benefit is dependent on:

• File access pattern
• Correct file access evaluation

Use performance views to select the candidate files:

• V$ASM_FILE
• V$ASM_DISK
• V$ASM_DISK_STAT

Performance benefit can be verified by testing.

• Review Automatic Workload Repository (AWR) reports before and after making a change.
• Use V$FILEMETRIC and V$FILEMETRIC_HISTORY.

Disk Group Templates

• Templates are used to set striping, redundancy, and region attributes for ASM files.
• Striping attribute options are:
• FINE: 128 KB stripe size
• COARSE: 1 allocation unit (AU_SIZE attribute) stripe size
• Redundancy attribute options are:
• MIRROR: Two-way mirroring
• HIGH: Three-way mirroring
• UNPROTECTED: No ASM mirroring
• A set of default templates is created for each disk group.
• Default template settings depend on disk group redundancy.
• The redundancy attribute applies only to NORMAL redundancy disk groups.

Viewing Templates

• In either an ASM or database instance, V$ASM_TEMPLATE displays one row for every template present in every disk group mounted by the ASM instance.
• The ASMCMD lstmpl command shows all the templates for a given disk group.

$ asmcmd lstmpl -l -G data

The following query lists all the templates associated with the DATA disk group. The SYSTEM column returns Y for system-generated templates and N for user-defined templates.

SQL> SELECT T.NAME, T.REDUNDANCY, T.STRIPE, T.SYSTEM

2 FROM V$ASM_TEMPLATE T, V$ASM_DISKGROUP G

3 WHERE T.GROUP_NUMBER = G.GROUP_NUMBER

4 AND G.NAME = 'DATA';

Managing Disk Group Templates

Creating your own templates allows you to set the right combination of attributes to meet your requirements. It also allows you to specify an intuitive name for the attribute set.

For example, in a normal or high redundancy disk group, you might use a template with a redundancy setting of UNPROTECTED to create transient files without the overhead of mirroring. This can be a useful way of creating short-term databases for testing and development purposes.



SQL> ALTER DISKGROUP DATA ADD TEMPLATE unprot ATTRIBUTES (UNPROTECTED);

SQL> ALTER DISKGROUP DATA ADD TEMPLATE reliable ATTRIBUTES (HIGH FINE);

SQL> ALTER DISKGROUP DATA MODIFY TEMPLATE DATAFILE ATTRIBUTES (FINE);



Managing Disk Group Templates with ASMCMD

Use the mktmpl statement to add disk group templates.

ASMCMD> mktmpl -G DATA -–redundancy unprotected unprotect;

Use the chtmpl command to modify disk group templates.

ASMCMD> chtmpl –G DATA -–striping fine DATAFILE;

Use the rmtmpl command to drop disk group templates.

ASMCMD> rmtmpl –G DATA unprotect;

Use the lstmpl command to view disk group templates.

ASMCMD> lstmpl –G DATA


Using Disk Group Templates

You can apply disk group templates to newly created files in the following ways:

Alias file name with template

SQL> ALTER TABLESPACE myspace ADD
2 DATAFILE '+DATA(mytemplate)/mydir/myspace02.dbf' SIZE 50M;

Incomplete file name with template

SQL> ALTER TABLESPACE myspace ADD
2 DATAFILE '+DATA(mytemplate)' SIZE 50M;

DB_CREATE_FILE_DEST database initialization parameter

SQL> ALTER SYSTEM SET DB_CREATE_FILE_DEST = '+DATA(mytemplate)';

SQL> CREATE TABLESPACE yourspace;

ASM Directories

ASM disk groups contain a system-generated hierarchical directory structure for storing ASM files. The system-generated file name that ASM assigns to each file represents a path in this directory hierarchy. The following is an example of a system-generated file name:

+DATA/racdb/DATAFILE/SYSTEM.262.676172197

The plus sign represents the root of the ASM file system. The DATA directory is the parent directory for all files in the DATA disk group. The racdb directory is the parent directory for all files in the racdb database, and the DATAFILE directory contains all data files for the racdb database.

You can create your own directories within this hierarchy to store aliases that you create. Thus, in addition to having user-friendly alias names for ASM files, you can have user-friendly paths to those names. For example, the following user-defined directory might be used to store a collection of alias file names:

+DATA/racdb/my_directory

User-defined directories may be created at any level below the disk group directories. That is, you cannot create a user-defined directory at the root (+) level.

Managing ASM Directories

SQL> ALTER DISKGROUP DATA ADD DIRECTORY '+DATA/mydir';

SQL> ALTER DISKGROUP DATA
2 RENAME DIRECTORY '+DATA/mydir' TO '+DATA/myotherdir';

The ASMCMD commands:

• mkdir: Makes directory
• mv: Renames a file or directory
• rm: Removes a file or directory and its aliases
• rmalias: Removes the alias only

You can also perform all these operations from Enterprise Manager.

Managing Alias File Names

SQL> ALTER DISKGROUP DATA ADD ALIAS '+DATA/mydir/system.dbf'
2 FOR '+DATA/sample/datafile/system.262.676172197';

SQL> ALTER DISKGROUP DATA RENAME ALIAS '+DATA/mydir/datafile.dbf'
2 TO '+DATA/payroll/compensation.dbf';

ASM File Creation

Single File Creation: Examples

Alias ASM file name

SQL> ALTER TABLESPACE myspace ADD
2 DATAFILE '+DATA/mydir/myspace02.dbf' SIZE 50M;


Alias file name with template

SQL> ALTER TABLESPACE myspace ADD
2 DATAFILE '+DATA(mytemplate)/mydir/myspace03.dbf';


Incomplete file name

SQL> ALTER TABLESPACE myspace ADD
2 DATAFILE '+DATA' SIZE 50M;

Note: When the SIZE parameter is not given, the SIZE defaults to 100 MB.


Multiple File Creation: Example

• Create an online redo log group with two members.
• Set the following database initialization parameters:

        DB_CREATE_ONLINE_LOG_DEST_1 = '+DATA'
        DB_CREATE_ONLINE_LOG_DEST_2 = '+FRA'

• Then create the log group without any file references:

        SQL> ALTER DATABASE ADD LOGFILE;

• The resulting fully qualified file names are:

    +DATA/ORA11g/ONLINELOG/group_5.269.699798885
    +FRA/ORA11g/ONLINELOG/group_5.256.699799169


Multiple file creation operations work only in conjunction with incomplete ASM file names. In such operations, the incomplete file name reference is implied through the use of the following database initialization parameters:

• DB_CREATE_FILE_DEST
• DB_CREATE_ONLINE_LOG_DEST_<n> (where <n> = 1, 2, 3, 4 or 5)

The above example illustrates how an online redo log group containing two members is created without any explicit file references.

Although it is recommended that you use the Database Configuration Assistant (DBCA) to create databases, it is possible to set DB_CREATE_FILE_DEST to an ASM disk group and create a complete database using the following simple statement:

CREATE DATABASE sample;

This statement creates a database with at least the following ASM files:

• A SYSTEM tablespace data file in the disk group specified in DB_CREATE_FILE_DEST
• A SYSAUX tablespace data file in the disk group specified in DB_CREATE_FILE_DEST
• A multiplexed online redo log with two log groups. Each log group will have one member in the disk group specified in DB_CREATE_FILE_DEST and a second member in the disk group specified in DB_RECOVERY_FILE_DEST.

Fully Qualified ASM File Names

Every file created in ASM gets a system-generated file name, known as the fully qualified file name. You cannot set the fully qualified file name. The fully qualified file name represents a complete path name in the ASM file system. An example of a fully qualified file name is:

+DATA/racdb/DATAFILE/SYSTEM.262.676172197

You can use the fully qualified file name to reference (read or retrieve) an ASM file.

You can also use other abbreviated file name formats, such as an alias ASM file name to reference an ASM file.

You can find the fully qualified file name in database views displaying Oracle Database file names, such as V$DATAFILE and V$LOGFILE.

A fully qualified file name has the following form:

+group/dbname/file_type/file_type_tag.file.incarnation

where:

• +group is the disk group name preceded by a plus sign. You can think of the plus sign as the root of the ASM file system, similar to the slash (/) on UNIX or Linux file systems.
• dbname is the DB_UNIQUE_NAME of the database to which the file belongs.
• file_type is the Oracle Database file type.
• file_type_tag is type-specific information about the file.
• file.incarnation is the file/incarnation pair, used to ensure uniqueness.

Examples

+DATA/ORA11g/DATAFILE/SYSTEM.262.676172197
+DATA/ORA11g/PARAMETERFILE/spfile.268.676172697
+DATA/ORA11g/CONTROLFILE/Current.257.676172363
+DATA/ORA11g/ONLINELOG/group_1.256.676172371
+FRA/ORA11g/CONTROLFILE/Backup.275.676172942


Other ASM File Names

In addition to the fully qualified file name, the following other ASM file names can be used in various different situations:

Numeric ASM file name

Format: <+group>.<file>.<incarnation>
Example: +DATA.262.676172197

Alias ASM file name

Format: <+group>/<alias>
Example: +DATA/my_dir/my_other_dir/my_file_name.dbf

Alias ASM file name with template

Format: <+group>(<template>)/<alias>
Example: +DATA(my_template)/my_dir/my_other_file_name.dbf

Incomplete ASM file name

Format: <+group>

Incomplete ASM file name with template

Format: <+group>(<template>)
Example: +DATA(my_template)

Accessing ASM Files by Using ASMCMD

ASMCMD is a command-line utility that you can use to view and manipulate files and directories within ASM disk groups. ASMCMD can list the contents of disk groups, perform searches, create and remove directories and aliases, display space utilization, and more.

The ASMCMD commands include many commands that perform the same basic functions as their UNIX/Linux counterparts. These include: cd, cp, du, find, ls, mkdir, pwd, and rm. There are additional commands that perform ASM-specific functions.

[grid@host01 ~]$ asmcmd
ASMCMD> cd +DATA/racdb/DATAFILE
ASMCMD> ls -l SYS*
Type Redund Striped Time Sys Name
DATAFILE MIRROR COARSE AUG 03 16:00:00 Y SYSAUX.257.692926339

DATAFILE MIRROR COARSE AUG 03 16:00:00 Y SYSTEM.256.692926339
ASMCMD> cd ..
ASMCMD> pwd
+DATA/racdb/DATAFILE
ASMCMD> exit

When you invoke the ASMCMD utility from the Grid software $ORACLE_HOME, the utility attempts to connect AS SYSASM. The ASMCMD utility attempts to connect AS SYSASM, so the user that invokes ASMCMD must be a member of the OSASM group. When connecting from a $ORACLE_HOME database, ASMCMD attempts to connect AS SYSDBA.


OS user must be a member of the OSDBA group for ASM. Set the ORACLE_SID environment variable to the local name of the database instance. Any OS user who is a member of the appropriate OS group may connect with ASMCMD to a local instance, and specify the connect role with the -a option.

Accessing ASM Files by Using DBMS_FILE_TRANSFER

The DBMS_FILE_TRANSFER package provides procedures to copy ASM files within a database or transfer binary files between databases that use ASM. The DBMS_FILE_TRANSFER package has the following procedures:

• COPY_FILE: Reads a file from a source directory and creates a copy of the file in a destination directory. The source and destination directories can both be in a local file system or in an ASM disk group. You can also use this procedure to copy between a local file system and an ASM disk group; the copy operation is valid in either direction.
• GET_FILE: Contacts a remote database to read a remote file and then creates a copy of the file in the local file system or ASM disk group
• PUT_FILE: Reads a local file or ASM disk group and contacts a remote database to create a copy of the file in the remote file system

When using DBMS_FILE_TRANSFER, note the following:

• The size of the copied file must be a multiple of 512 bytes.
• The size of the copied file must be less than or equal to two terabytes.
• Transferring a file is not transactional. To guarantee consistency, bring files offline when the database is in use.
• The copied file is treated as a binary file, and no character set conversion is performed.

Example:

Copy a local database file into ASM.

SQL> CREATE DIRECTORY dgb AS '+DATA/dbfiles';
SQL> CREATE DIRECTORY loc AS '/u01/app/oracle/oradata/db';
SQL> BEGIN
2 DBMS_FILE_TRANSFER.COPY_FILE('loc','tmp.dbf','dgb','tmp.dbf');
3 END;
4 /

Accessing ASM Files by Using XML DB

ASM files and directories can be accessed through a virtual folder in the Oracle Database XML DB repository.

The repository path to the virtual folder is /sys/asm.

/sys/asm provides a means to access and manipulate the ASM files and directories with programmatic APIs, such as the DBMS_XDB package, and with XML DB protocols such as FTP and HTTP/WebDAV.

You must log in to XML DB as a user other than SYS and that user must be granted the DBA role to access /sys/asm with XML DB protocols.

A typical use for this capability might be to view /sys/asm as a web folder in Windows Explorer, and then copy a Data Pump dumpset from an ASM disk group to an operating system file system by dragging and dropping.

Under /sys/asm, the folder hierarchy is defined by the structure of an ASM fully qualified file name. That is, the /sys/asm virtual folder contains one subfolder for every mounted disk group, and each disk group folder contains one subfolder for each database that uses the disk group.

In addition, a disk group folder might contain files and folders corresponding to aliases created by the administrator. Continuing the hierarchy, the database folders contain ASM file type folders, which contain the ASM files.

Note: XML DB must be configured to enable FTP and HTTP/WebDAV. Use EM or the script provided at $ORACLE_HOME/rdbms/admin/catxdbdbca.sql to do this. 

 

 

Accessing ASM Files by Using RMAN

The Oracle Recovery Manager (RMAN) is the preferred method for backup and recovery of databases contained in ASM. RMAN is very well integrated with ASM and is also used by third-party Oracle Database backup and recovery managers.

RMAN can back up from and recover to ASM. It can also use ASM as a store for backup sets.

Depending on the context, RMAN can reference individual ASM files or entire disk groups. For example, the following RMAN BACKUP command refers to an individual ASM file on the second line and also refers to an ASM disk group on the third line.

RMAN> BACKUP AS COPY

DATAFILE "+DATA/rdbms/datafile/tbs_5.256.565313879"

FORMAT "+DATA2";

How to migrate existing databases into ASM

RMAN can also be used to migrate existing databases into ASM. This can be done one file at a time or a complete database can be migrated into ASM in the same operation.

The following provides an example of the procedure you can use to relocate your entire database to an ASM disk group (assuming the use of a server parameter file):

• Obtain the file names of the current control files and online redo logs using V$CONTROLFILE and V$LOGFILE.
• Shut down the database consistently.
• Modify the server parameter file of your database as follows:
• Start the database with the NOMOUNT option.
• Set the DB_CREATE_FILE_DEST parameter to the desired ASM disk group.
• Remove the CONTROL_FILES parameter. It will be re-created automatically.
• Edit to replace the placeholder file and disk group references with your actual locations, and then run the following RMAN command file. This backs up the database, switches the current data files to the backups, renames the online redo logs, and re-creates the temporary tablespaces.

RESTORE CONTROLFILE FROM '/u1/c1.ctl';
ALTER DATABASE MOUNT;
BACKUP AS COPY DATABASE FORMAT '+YOURDG';
SWITCH DATABASE TO COPY;
# Repeat command for all online redo log members
SQL "ALTER DATABASE RENAME '/u1/log1' TO '+YOURDG' ";
ALTER DATABASE OPEN RESETLOGS;
# Repeat commands for all temporary tablespaces
SQL "ALTER TABLESPACE temp ADD TEMPFILE";
SQL "ALTER DATABASE TEMPFILE '/u1/temp1' DROP";

• Delete the old database files.

Note: This example illustrates the procedure for migrating a database into ASM. You may want to use other options and settings to migrate your specific databases into ASM. For a complete discussion of this topic, refer to the Oracle Database Backup and Recovery User’s Guide 11g Release 2.

Clients that connect directly to ASM include

• Oracle Database: Oracle Database is the most fundamental ASM client. It makes requests of ASM relating to numerous types of activities such as ASM File creation.
• ASM Cluster File System: This depends on ASM to provide the ASM volumes.
• ASM Clusterware: If the Oracle Cluster Registry (OCR), voting files, or ASM server parameter file (SPFILE) is stored on an ASM disk group, the ASM instance is a client of itself.
• ASMCA: ASM Configuration Manager is a graphical interface that allows you to manage ASM instances, disk groups, and volumes.
• Enterprise Manager: This allows you to manage and monitor the ASM instance directly, and indirectly through the database.
• Clusterware: Clusterware uses ASM to store the OCR and voting disk files by default.
• SQL clients (such as SQL*Plus): A series of ASM-specific SQL commands (such as CREATE DISKGROUP) provide the most fundamental management client for ASM.
• ASMCMD: ASM command-line interface is used to interrogate and manage ASM. It includes many UNIX-like commands that can be used to manage the files and directories in an ASM system.

In addition to clients that connect to ASM directly, there are a series of interfaces provided by Oracle Database that can be used to manipulate ASM in various different ways. These include:

• SQL: When an Oracle Database is managed under ASM, activities that create and delete ASM files (such as CREATE DATABASE and DROP TABLESPACE) will implicitly interact with the underlying ASM instance. A database instance will also directly read and write ASM files as a result of SQL data manipulation language (DML) commands (INSERT, UPDATE, and DELETE). However, operations that involve space management (such as extending a data file) will also require interaction with the ASM instance.
• Oracle Recovery Manager (RMAN): RMAN is Oracle’s recommended backup and recovery utility. RMAN is well integrated with ASM and can be used to migrate non-ASM databases into ASM.
• XML DB: ASM files and directories can be accessed through a virtual folder in the XML DB repository. XML DB provides a means to access and manipulate the ASM files and directories with programmatic APIs, such as the DBMS_XDB package, and with XML DB protocol services such as FTP and HTTP/WebDAV.
• DBMS_FILE_TRANSFER: The DBMS_FILE_TRANSFER package provides procedures to copy ASM files within a database or to transfer binary files between a local ASM instance and a remote database file. DBMS_FILE_TRANSFER.COPY_FILE supports all transfer combinations involving ASM and/or your local file system, namely:
• Local file system to local file system
• Local file system to ASM
• ASM to local file system
• - ASM to ASM

Oracle file types and Oracle ASM file type tags

Oracle file types and Oracle ASM file type tags

Oracle ASM File Type	Description	Oracle ASM File Type Tag	Comments
CONTROLFILE	Control files and backup control files	Current Backup	Archive Backup
DATAFILE	Data files and data file copies	tblspname	Name of the tablespace into which the file is added
ONLINELOG	Online logs	group_loggroup#
ARCHIVELOG	Archive logs	thread_thread#_seq_sequence#
TEMPFILE	Tempfiles	tsname	Name of the tablespace into which the file is added
BACKUPSET	Data file and archive log backup pieces; data file incremental backup pieces	spfile?_timestamp	spfile? can take one of two values: s indicates that the backup set includes the spfile; n indicates that the backup set does not include the spfile. timestamp is the time that the backup is started.
PARAMETERFILE	Persistent parameter files	spfile	Name of the SPFILE
DATAGUARDCONFIG	Data Guard configuration file	db-unique-name	Data Guard uses the value of the DB_UNIQUE_NAME initialization parameter.
FLASHBACK	Flashback logs	log_flashbacklog#
CHANGETRACKING	Block change tracking data	ctf	Used during incremental backups
DUMPSET	Data Pump dumpset	user_obj#_file#	Dump set files encode the user name, the job number that created the dump set, and the file number as part of the tag.
XTRANSPORT	Data file convert	tblspname	Name of the tablespace where the Oracle ASM metadata is added
AUTOBACKUP	Automatic backup files	spfile?_timestamp	spfile? can take one of two values: s indicates that the backup set includes the spfile; n indicates that the backup set does not include the spfile. timestamp is the time that the backup is started.
ASMPARAMETERFILE	Oracle ASM persistent parameter files	spfile	Name of the Oracle ASM SPFILE
OCRFILE	Oracle Clusterware Registry files	ocrfile	Name of the OCR files