Oracle 11g ASM (Automatic Storage Management) Features, advantages and benefits

ASM is built-in database file system which is used for database related objects like tables, indexes, tempfiles, backup sets, control files, parameter files, redo logs, archive logs, dump sets. ASM simplifies the Oracle database storage administration. It is the centralized way to administer Oracle database disk storage.
ASM is a volume manager and a file system for Oracle database files which supports single instance Oracle Database and Oracle RAC configurations. It is an alternative to conventional volume managers, file systems and raw devices.

Advantages of ASM
          ASM allows you to reduce the management of Oracle files into ASM disk groups. It provides data redundancy configuration, re-balancing operations. When you install ASM on top of cluster ware, it can share the database related files. You can configure the flashback recovery area on an ASM disk group, so backup can also be performed through ASM. The content of files that are stored in a distributed disk group or striped to eliminate hot spots and to proved uniform performance across disks. That means performance is comparable to the performance of the raw devices.

High availability with reduced downtime: ASM provides the hot swappable disks. You can add or remove disks from a disk group while a database is online. When you perform add or remove disks from a disk group, ASM automatically redistributes the file contents and eliminates the need for downtime.

Data redundancy: ASM provides flexible server-based mirroring options. The ASM normal and high redundancy disk groups enable 2-way and 3-way mirroring respectively. You can use RAID storage subsystems to perform the mirroring

Reduces the administrative overhead: ASM accomplish this by consolidating data storage into a small number of disk groups. This enables you to consolidate the storage for multiple databases and to provide for improved I/O performance.

ASM uses the Oracle Managed Files(OMF ) for simplified database file management.

Compatibility with other storage systems: ASM can support with other storage management options such as raw disks and third-party file systems. This feature simplifies the integration ASM with pre-existing environments.

It has easy to use management interfaces such as SQL*plus, ASMCMD command-line interface and Oracle EM (enterprise Manager). Using OEM wizard you can easily migrate a non-ASM database files to ASM.

In an ASM instance, you can store database datafile, redo log files, archive log files, backup files, datapump dump files, change-tracking files and control files of one or several oracle database. Another feature of ASM is elimination of fragmentation.

Load balancing: ASM provides dynamic parallel load balancing which helps to prevent hot spots. IO spread evenly across available disks.
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