Oracle ASM Day-to-Day Operations – ASMCMD, Oracle ASMLib and SQL*Plus

October 7, 2026 3 Min Read

Oracle ASM administration involves several tools depending on the task being performed. For day-to-day DBA activities, I commonly use ASMCMD, Oracle ASMLib (oracleasm), and SQL*Plus connected as SYSASM.

I put together a collection of frequently used ASM commands that can serve as a quick reference when managing ASM environments.

The complete command reference is available on GitHub:

GitHub: Oracle ASM Day-to-Day Operations

What Does This Reference Cover?

The commands are organized into three main sections.

1. ASMCMD – Everyday ASM Administration

asmcmd provides a command-line interface for working with ASM disk groups and files.

The reference includes commonly used commands for:

Checking the ASM version
Listing disk groups, disks, and ASM files
Navigating ASM directories
Checking space usage
Searching for files
Creating and removing directories
Monitoring ASM disk I/O
Mounting and unmounting disk groups

It also includes examples of using ASMCMD in both interactive and non-interactive modes, which can be useful when incorporating ASM commands into shell scripts.

2. Oracle ASMLib – ASM Disk Management

The oracleasm utility is useful when managing ASM disks at the operating-system level.

The reference includes commands for:

Configuring Oracle ASMLib
Starting and stopping the Oracle ASMLib service
Checking ASMLib status
Listing ASM disks
Creating and deleting ASM disks
Querying disk labels
Renaming ASM disks
Scanning for newly created or removed disks

For RAC environments, it also notes the common practice of creating the ASM disk on one node and running oracleasm scandisks on the remaining nodes so they can discover it.

3. SQL*Plus as SYSASM – Disk Group Administration

For ASM configuration and disk group operations, SQL*Plus connected with the SYSASM privilege provides the greatest level of control.

The reference includes examples for:

Checking ASM instance status
Reviewing disk group capacity
Creating disk groups with External, Normal, and High redundancy
Adding disks to existing disk groups
Dropping disks
Controlling ASM rebalance power
Monitoring rebalance operations
Dropping disk groups

For example, the reference includes commands to monitor active ASM rebalance operations through V$ASM_OPERATION.

ASM Environment Setup

One practice I follow is maintaining separate Oracle environment files for ASM and database administration.

For example:

vi asm.env

export ORACLE_SID=+ASM1
export ORACLE_HOME=/u01/app/oracle/19.3.0/grid/bin

The ASM environment can then be loaded before running ASM administration commands:

. asm.env

Keeping separate ASM and database environment files helps avoid accidentally running commands against the wrong Oracle home or instance.

GitHub Command Reference

Rather than duplicating all the commands in this article, I have kept the complete command collection on GitHub.

You can find the full examples here:

View Oracle ASM Day-to-Day Operations on GitHub

The repository includes practical examples covering ASMCMD, Oracle ASMLib, disk group administration, disk operations, and ASM rebalance monitoring.

Conclusion

Oracle ASM administration usually requires switching between different tools depending on the task.

For most day-to-day activities:

ASMCMD is convenient for navigating and inspecting ASM storage, Oracle ASMLib helps manage ASM disks at the operating-system level, and SQL*Plus as SYSASM provides full control over ASM disk groups and rebalance operations.

This command collection is intended to serve as a simple reference that I can return to whenever performing common ASM administration activities.