In this case also as an extra check that we did not break anything. Proceeded with the remaining 8 Datafiles and when doing the rename step it was a good thing to see this below information in the Alert log:.
You are commenting using your WordPress. You are commenting using your Google account. You are commenting using your Twitter account. You are commenting using your Facebook account. Notify me of new comments via email. Notify me of new posts via email. Skip to content Home About. Scenario: Often on the web it is stated that you should not believe it just because it is printed. In this case, it is used in the file creation form.
The tablespace mytblspace is created and comprises one data file of size MB contained in the disk group data. The data file is set to auto-extensible with an unlimited maximum size. Alias names, or aliases, are intended to provide a more user-friendly means of referring to Oracle ASM files, rather than using the system-generated filenames.
You can create an alias in any system-generated or user-created Oracle ASM directory. The alias name must consist of the full directory path and the alias itself. The old and the new alias names must consist of the full directory paths of the alias names. The underlying file to which the alias refers is unchanged. Example fails because it attempts to drop a system-generated filename and this syntax is not allowed. You must use a fully qualified filename, or an alias name when specifying the file to delete.
The underlying file on the file system is not dropped when the alias is dropped. A file created using aliases is not an Oracle Managed File. Consequently, it is not automatically deleted. A point-in-time-recovery of a database might restore the database to a time before a tablespace was created. The restore does not delete the tablespace, but there is no reference to the tablespace or its data file in the restored database.
You could manually delete the data file. In Example , the alias name for the file is used to delete both the file and the alias from a disk group. Example Dropping a file and alias from a disk group using the alias name. In Example , the Oracle Managed Files system-generated file name is used to drop the file and any associated alias.
Example Dropping a file and alias from a disk group using the system-generated name. The system-generated filename that Oracle ASM assigns to each file represents a path in this directory hierarchy. The following is an example of a system-generated filename:. The plus sign represents the root of the Oracle ASM file system. The data directory is the parent directory for all files in the data disk group.
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 Oracle ASM files, you can have user-friendly paths to those names. It also describes how you can rename a directory or drop a directory. This section contains the following topics:. The parent directory must exist before attempting to create a subdirectory or alias in that directory. A directory must be created below the disk group level. Example Creating a new directory.
Example Creating a new subdirectory. System-created directories those containing system-generated names cannot be renamed. The root level disk group name cannot be renamed. Example Renaming a directory. You cannot drop a system-created directory. Example Dropping a directory. The folder is virtual because its contents do not actually reside in the repository; they exist as normal Oracle ASM files and directories. See "cp". If the database is not configured to use Oracle ASM, the folder is empty and no operations are permitted on it.
The Oracle ASM virtual folder contains folders and subfolders that follow the hierarchy defined by the structure of an Oracle ASM fully qualified file name. Figure illustrates an example of this hierarchy, which for simplicity, excludes directories created for aliases. 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 file type folders, which contain the Oracle ASM files.
Examples of Oracle ASM alias file names are:. Oracle Database references database files by their alias file names, but only if you create the database files with aliases. If you create database files without aliases and then add aliases later, the database references the files by their fully qualified file names.
The following are examples of how the database uses alias file names:. Files created using an alias file name are not considered Oracle Managed Files and might require manual deletion in the future if they are no longer needed. This example assumes that a directory has been created in disk group data to contain the alias name and that the user-defined template exists.
Because an alias is used when creating the data file, the file is not an Oracle Managed Files OMF file and the file is not automatically deleted when the tablespace is dropped. To drop the file manually after the tablespace has been dropped, use the following SQL statement:.
It has the following format:. Alias file names with template behave identically to alias file names except that a file created with an alias file name with template receives the attributes specified by the named template. The template must belong to the disk group that the file is being created in. Explicitly specifying a template name, as in the previous example, overrides the system default template for the type of file being created. Files created using an alias file name with template are not considered Oracle Managed Files and might require manual deletion in the future if they are no longer needed.
Example for information about creating objects using an alias name. Incomplete Oracle ASM file names are used only for file creation operations and are used for both single and multiple file creation. They consist only of the disk group name.
The system template that is used is determined by the file type that is being created. With this setting, every time you create a tablespace, a data file is created in the disk group data , and each data file is assigned a different fully qualified name.
Incomplete Oracle ASM file names with templates are used only for file creation operations and are used for both single and multiple file creation.
They consist of the disk group name followed by the template name in parentheses. When you explicitly specify a template in a file name, Oracle ASM uses the specified template instead of the default template for that file type to determine attributes for the file. Any Oracle Managed File is automatically deleted when it is no longer needed. Using the Oracle Managed Files feature for operating system files, you can specify a directory as the default location for the creation of data files, temporary files, redo log files, and control files.
Using the Oracle Managed Files feature for Oracle ASM, you can specify a disk group, in the form of an incomplete Oracle ASM file name, as the default location for creation of these files, and additional types of files, including archived log files. As for operating system files, the name of the default disk group is stored in an initialization parameter and is used whenever a file specification for example, DATAFILE clause is not explicitly specified during file creation.
The following initialization parameters accept the multiple file creation context form of Oracle ASM file names as a destination:. The following initialization parameters accept the multiple file creation context form of the Oracle ASM file names and Oracle ASM directory names as a destination:. Specifies a default disk group or Oracle ASM directory as destination for archiving redo log files. Optional parameter to use to specify a default disk group or Oracle ASM directory as destination for archiving redo log files.
Use when specifying only one destination. Relevant only for a standby database. It specifies a default disk group or Oracle ASM directory that is the location of archive logs arriving from a primary database.
Not discussed in this book. This parameter has been deprecated. File extents are stored using the attributes defined by the default template for a data file. Oracle Database Reference for information about initialization parameters. Oracle Database Administrator's Guide for information about initialization parameter files. If you are creating a file for the first time, then use the creation form of an Oracle ASM file name. If the Oracle ASM file exists, then you must use the reference form of the file name, and if you are trying to re-create the file, you must add the REUSE keyword so that the space is reused for the new file.
In this case, it is used in the file creation form. The tablespace mytblspace is created and comprises one data file of size MB contained in the disk group data. The data file is set to auto-extensible with an unlimited maximum size.
Oracle Database provides a set of dynamic performance views to show a complete mapping of a file to intermediate layers of logical volumes to actual physical devices. Using these dynamic views, you can locate the exact disk on which any block of a file resides.
Oracle Database communicates with a background process called FMON to manage the mapping information. The database instance does not have to be shut down to set this parameter. In a cold startup scenario, the Oracle Database has just started and no mapping operation has been invoked yet. This forces all of the mapping information in the SGA to be flushed to disk.
Oracle Database Reference for information about dynamic views. Alias names, or aliases, are intended to provide a more user-friendly means of referring to Oracle ASM files, rather than using the system-generated file names. You can create an alias in any system-generated or user-created Oracle ASM directory. The alias name must consist of the full directory path and the alias itself. Example adds a new alias name for a system-generated file name. The old and the new alias names must consist of the full directory paths of the alias names.
Example renames an alias. The underlying file to which the alias refers is unchanged. Example drops an alias. Example fails because it attempts to drop a system-generated file name and this syntax is not allowed. You must use a fully qualified file name, or an alias name when specifying the file to delete.
This redistribution is known as reba lancing. It is done in the background and with minimal impact to database performance. When you request to remove a disk, Oracle ASM first rebalances the disk group by evenly relocating all file extents from the disk being removed to the other disks in the disk group.
Oracle ASM automatically assigns file names when files are created, and automatically deletes files when they are no longer needed. Oracle recommends that you use Oracle ASM for your database file storage, instead of raw devices or the operating system file system.
The Oracle ASM instance is tightly integrated with the database instance. Only one Oracle ASM instance is required for each node, regardless of the number of database instances on the node. Administ ering Oracle ASM. You configure Oracle ASM by creating disk gr oups that become the default location for files created in the database.
The disk group type determines how Oracle ASM mirrors files. When you create a disk group, you indicate whether the disk group is a normal redundancy disk group 2-way mirroring for most files by default , a high redundancy disk group 3-way mirroring , or an external redundancy disk group no mirroring by Oracle ASM.
You use an external redundancy disk group if your storage system does mirroring at the hardware level, or if you have no need for redundant data. The default disk group type is normal redundancy.
A disk group consists of a grouping of disks that are managed as a unit. These disks are referred to as Oracle ASM disks. An Oracle ASM disk can be a disk device, a partition, or a network-attached file. Disco very is the process of finding all disks that were prepared for Oracle ASM by your system administrator, examining their disk headers, and determining which disks belong to disk groups and which are available for assignment to disk groups. Oracle ASM discovers disks in the paths that are listed in an initialization parameter, or if the parameter is NULL , in an operating system—dependent default path.
Failure gro ups define Oracle ASM disks that share a common potential failure mechanism. Failure groups are used to determine which Oracle ASM disks to use for storing redundant copies of data. For example, if 2-way mirroring is specified for a file, then Oracle ASM automatically stores redundant copies of file extents in separate failure groups.
Failure groups apply only to normal and high redundancy disk groups. You can define the failure groups in a disk group when you create or alter the disk group, or let Oracle ASM automatically place each disk into its own failure group. For most systems, the default failure groups work well to prevent data loss. Oracle Automatic Storage Management Administrator's Guide for additional information about failure groups, and for instructions for configuring failure groups. The procedure for accessing the Oracle ASM Home page differs depending on whether your database is a single-instance database or an Oracle Real Application Clusters database.
Details are provided in the following sections:. Depending on your configuration, the Database Control OC4J instance may also be running on other nodes.
Using Oracle Enterprise Manager, you can monitor the total capacity of your disk groups, including the amount of unused space and the amount of unused space that can be safely utilized after taking mirroring into account.
Have disk groups with different redundancy levels normal, high, or external , depending on availability requirements and storage system capabilities. Disks in a disk group should have similar size and performance characteristics.
The Create Disk Group page appears.
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