In the realm of modern database management, Oracle Automatic Storage Management (ASM) emerges as a game-changing solution, revolutionizing how organizations log files and handle complex storage requirements within their existing Oracle Database environments.

Designed explicitly for storage management across Oracle database instances, ASM provides a seamless and efficient method for optimizing data storage and simplifying administrative tasks.

From its dynamic ASM Disk Group architecture to its ability to optimize distribution for database files, Oracle ASM is an indispensable tool for organizations seeking robust, automated, and high-performance storage tools for their Oracle Database deployments.

This article dives into the intricacies of Oracle ASM, exploring its unique features and the transformative impact it has on database performance and offering insight into our Oracle consulting services to give you a better idea of what to expect when partnering with us.

What is Automatic Storage Management?

Automatic Storage Management (ASM) offers fully integrated, high-performance database file system and disk manager capabilities that enable the actual database to manage storage instead of requiring administration staff to do it, eliminating manual effort required to manage multiple Oracle database files.

Intelligent ASM functionality provides the following benefits for enterprise users:


ASM ensures the even distribution of database files across all disks in a disk group to improve overall performance, optimize utilization, and eliminate the need for I/O performance tuning and regular monitoring.


Unlike operating system mirroring which mirrors at the disk level, ASM mirrors at the file level, increasing availability by optionally mirroring any file and avoiding critical data loss caused by disk failures.

Mirroring means keeping redundant, or mirrored, copies of each aspect of the file on a different disk from the original copy. This way, if a disk fails, ASM can access affected files by accessing mirrored copies on the remaining disks in the disk group.

File creation and deletion:

ASM automatically assigns filenames when new files are created and automatically deletes files when they are no longer needed. This empowers customers to reduce administration tasks by enabling files stored in ASM disk groups to be Oracle-managed files.

Storage reconfiguration and rebalancing:

ASM allows users to add or remove disks from an existing disk storage system during operation and automatically redistributes the data from each disk to other disks in the disk group.

This rebalancing process evenly distributes all file extents from the disk being removed to other disks in the disk group with minimal impact on database performance or productivity.

Understanding Oracle Automatic Storage Management (ASM)

What is ASM Oracle?

Oracle ASM (Automatic Storage Management) offers intelligent file system and volume management functionality for Oracle database files, supporting single-instance Oracle Database and Oracle Real Application Clusters (RAC) configurations and integrations.

By providing an alternative to traditional volume managers, raw devices, and file systems, Oracle ASM has become Oracle’s recommended storage management solution, leading to better data file storage on disk groups, even file distribution across disk groups, and simplified database file management.

Critical Features

Dynamic Disk Group Architecture: Oracle ASM uses a dynamic disk group architecture, allowing for the online addition or removal of storage devices. This flexibility ensures storage capacity can be adjusted as needed, accommodating changing requirements without interrupting existing database operations.

Automatic Storage Rebalancing: The Oracle ASM platform automates storage rebalancing by redistributing data across disks within a disk group. This automatic process ensures even disk utilization and optimal performance. As new storage devices are added or removed, Oracle ASM automatically adjusts the data distribution to maintain balance.

Compatibility with Oracle Recovery Manager (RMAN): Oracle ASM offers seamless integrations with Oracle Recovery Manager (RMAN) to streamline backup and recovery operations. This integration simplifies the data backup process and enhances recovery capabilities, providing a cohesive solution for data protection within Oracle Database environments.

Automatic Disk Discovery: Automatic disk discovery capabilities in Oracle ASM simplify the initial setup and ongoing administration of disks and disk groups across the enterprise landscape. It automatically detects and configures storage devices, reducing the manual effort required for storage provisioning.

Fast Mirror Resync: In the event of a disk failure and subsequent replacement, Oracle ASM provides a quick and efficient mirror resynchronization process, ensuring no critical data is lost or existing operations are impacted. This accelerates the rebuilding of mirrored data, minimizing the time it takes to restore redundancy and ensuring continued data protection across disk groups.

Integration with Oracle Database: Designed specifically for Oracle Database environments, the Oracle ASM solution seamlessly integrates with Oracle Database instances. This tight integration simplifies storage administration tasks, enhances compatibility, and ensures optimal performance for Oracle Database workloads.

Oracle ASM Instances

An Oracle ASM instance is built on the same technology as an Oracle Database instance, however, because Oracle ASM is responsible for fewer tasks than a database, the ASM SGA (System Global Area) is smaller and more manageable than a database SGA.

By leveraging intutive Oracle Clusterware technology, users can group Oracle ASM instances as needed, outlining one Oracle ASM instance for each cluster node. In a situation where there are multiple database instances for different databases on the same node, the instances will share the same Oracle ASM instance on the existing node.

Oracle ASM metadata includes the following:

  • Specific file names of the files comprised in a disk group
  • Individual disks that belong to a disk group
  • Amount of space available for each disk group
  • Oracle ADM volume information
  • Location of each disk group data file extent
  • Log of information about atomically changing metadata blocks

Oracle ASM Disks

Disks refer to the storage groups used to manage essential data across Oracle ASM disk groups. With intelligent disk functionality, Oracle ASM evenly distributes files across all the disks in a disk group, enabling the maintenance of each disk at the capacity level and ensuring all the disks in a disk group have the same I/O load.

Here are a few key examples of Oracle ASK Disks:

  • Network-attached files (NFS)
  • A disk/partition from a specific storage array
  • Logical data volumes
  • A complete disk or partitions of a disk

Oracle ASM Files

Oracle ASM Files are files stored in Oracle ASM disk groups, enabling efficient communication between Oracle Database and Oracle ASM and ensuring optimal data performance and protection across the board. Each Oracle ASM file is stored in a single Oracle ASM disk group, and Oracle ASM creates file names for intelligent file and tablespace creation initiatives.

Users can store the following file types in Oracle ASM disk groups:

  • Data files and temporary data files
  • Control files
  • Data Pump dumpsets
  • Online redo, flashback, and archive logs
  • RMAN backups
  • Change tracking bitmaps
  • Disaster recovery configurations

Oracle ASM Disk Groups

A disk group consists of multiple disks containing the metadata required to manage space in each disk group, providing the fundamental object for Oracle ASM initiatives. Oracle ASM disk groups often contain files from different databases and enable databases to use files from multiple disk groups.

Disk groups are comprised of the following:

  • Files
  • Disks
  • Allocation units

Mirroring and Failure Groups

Oracle ASM mirroring offers more flexible features than traditional RAID mirroring capabilities, enabling users to store copies of data on multiple disks and protect core data integrity. Each mirroring level in which Oracle creates files in a disk group are determined by an existing disk group, making it easier to specify redundancy levels for each file and allocate extents for a mirrored file.

Oracle ASM disk group types are based on the following redundancy levels:

  • Normal: Used for two-way mirroring
  • High: Used for three-way mirroring
  • External: Used to avoid Oracle ASM mirroring, like when hardware RAID is configured for redundancy

Failure groups are used to place mirrored copies of data on a disk outlined for a specific failure group. External disk groups do not require failure groups, high redundancy disk groups require at least three failure groups, and normal redundancy disk groups require at least two failure groups.

Key Benefits of Oracle ASM for Enterprise Users

Here’s a closer look at the main advantages of ASM functionality:

Simplified Storage Management: Oracle ASM simplifies storage management by providing a centralized and automated approach to storage configuration and administration. It eliminates the need for manual tuning and simplifies routine storage tasks, reducing the administrative overhead associated with managing storage infrastructure.

Optimized Data Distribution: ASM optimizes data distribution across available storage devices, ensuring balanced I/O and enhancing overall database performance. This intelligent data distribution improves efficiency and reduces the likelihood of performance bottlenecks.

High Availability and Reliability: ASM is designed to provide high availability and reliability for database storage. It includes features such as mirroring and failure recovery, ensuring data protection and minimizing the risk of data loss in the event of hardware failures.

Scalability: Enterprises can easily scale their storage infrastructure by adding new disks to existing disk groups. This scalability ensures that organizations can accommodate growing data volumes and evolving business requirements without significant disruptions.

Simplified Backup and Recovery: ASM simplifies backup and recovery processes by providing integration with Oracle Recovery Manager (RMAN). This integration streamlines backup operations and enhances recovery capabilities, contributing to a more robust and efficient data protection strategy.

Cost-Efficient Storage Management: By automating storage management tasks and optimizing data distribution, ASM contributes to cost efficiency. Enterprises can achieve better utilization of storage resources, reduce the need for manual intervention, and ultimately lower the total cost of ownership for their storage infrastructure.

Improved Performance and Throughput: The intelligent management of storage resources by ASM contributes to improved database performance and throughput. By distributing data across available storage devices and optimizing I/O operations, ASM helps organizations achieve higher levels of efficiency and responsiveness in their database environments.

Partnering with the Best

From implementing Oracle Cloud applications for the first time to navigating integrations between the ASM instance and the database instance and maintaining critical data files, control files, and system files within the ASM architecture, Surety Systems can help.

Our senior-level Oracle consultant team has the knowledge, skills, and proven track record to handle your critical project initiatives, ensuring your business needs are met and your teams are prepared for change, no matter what.

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