Oracle ASM Cluster File system (ACFS) is a file system implemented within ASM.
It allows you to store almost anything you can imagine within ASM, such as files and backups—this even includes database executables. For more advanced options and large-scale architectures, you can use it to create snapshots and clones with Exascale Volumes, use it with Oracle ZDM, take snapshots at Exadata, etc.
The only things that should not be stored at ACFS are the root directory of the Grid Infrastructure and any files from Oracle that can be stored directly at Oracle ASM .
This document describes how to create an ACFS use it as a backup.
In our case, we’re going to create the file ` ACFS` within one of the existing disk groups; we’ll choose the FRA disk group to create the ` ACFS ` and perform the backup on that mount point.
You can create a new disk group (recommended), for example, with the name ACFSDG, and create the file ` ACFS ` on the newly created disk group.
Here’s an example of how to do it.
https://oracleconraul.com/en/index.php/2025/02/03/oracle-asm-cluster-file-system-acfs-restart/
Keep in mind that the space you are using is ASM space, so you are using space from the disks assigned to that disk group, with all that that entails. That is why it is recommended to create a new disk group. In our case, since this is a test environment, we will do it on an existing disk group.
We load the ASM environment variables ASM check the available space with the lsdg command.
From the 20G available in the "FRA" disk group, in the "Usable_file_MB" column, we are going to create a 5Gb cluster file system ( ASM ) (ACFS).
- Create an Oracle volume on a disk group mounted with ASM.
We will use the volcreate command to create a volume in the ASM disk group, in our case FRA.
oracle> asmcmd
ASMCMD> volcreate -G FRA -s 5g volume1
2. Displays information about Oracle volumes.
We verify that the volume has been created correctly.
ASMCMD> volinfo -G FRA volume1
Diskgroup Name: FRA
Volume Name: VOLUME1
Volume Device:asm
State: ENABLED
Size (MB): 5120
Resize Unit (MB): 64
Redundancy: MIRROR
Stripe Columns: 8
Stripe Width (K): 1024
Usage:
Mountpath:
It is important to verify the disk volume in this case: asm. We will use it for the next step.
3. Create a new ACFS file system
With the root user, we execute the following:
oracle@oracle21dg> /sbin/mkfs -t acfs /dev/asm/volume1-45
mkfs.acfs: version = 21.0.0.0.0
mkfs.acfs: on-disk version = 50.0
mkfs.acfs: volume = /dev/asm/volume1-45
mkfs.acfs: volume size = 5368709120 ( 5.00 GB )
mkfs.acfs: file system size = 5368709120 ( 5.00 GB )
mkfs.acfs: Format complete.
4. Set up the ASM Cluster file System.
We created the /backup directory, changed its owner to oracle , and mounted the ASM cluster file system.
root@localhost ~]# mkdir /backup
[root@localhost ~]# chown oracle:oracle
[root@localhost ~]# /bin/mount -t acfs asm/backup
4. Register the file system in the clusterware.
This step is very important because it will cause ACFS automatically ACFS the mount point, in our case /backup. This prevents the mount point from failing to mount automatically after a reboot, which would result in it being inaccessible.
/sbin/acfsutil registry -a asm /backup
5- Verify that the file system has been created.
With the ASM environment variables, you can check with theASM view that the volume has been created correctly.
Using the crs command, we verify that the acfs volume acfs correctly registered in the cluster.
oracle21dg> crsctl status res -t
ora.fra.volume1.acfs
ONLINE ONLINE mounted on /backup,STABLE
ONLINE ONLINE mounted on /backup,STABLE
We can now use the ACFS system. In our case, we will use it to perform backups directly in ASM.
We connect to the database and create the directory to perform the export on the new ACFS /backup).
SQL>create directory EXPORT as '/backup';
Directory created.
We launch the export.
oracle@oracle21dg> expdp system/oracleconraul@test schemas=system directory=EXPORT dumpfile=exp_system.dmp logfile=exp_system .log
Export: Release 21.0.0.0.0 – Production on Mon Dec 1 16:16:23 2025
Version 21.3.0.0.0
Copyright (c) 1982, 2021, Oracle and/or its affiliates. All rights reserved.
Connected to: Oracle Database 21c Standard Edition 2 Release 21.0.0.0.0 – Production
Starting “SYSTEM.” “SYS_EXPORT_SCHEMA_01”: system/@test schemas=system directory=EXPORT dumpfile=exp_system.dmp logfile=exp_system.log
Processing object type SCHEMA_EXPORT/TABLE/TABLE_DATA
Processing object type SCHEMA_EXPORT/TABLE/INDEX/STATISTICS/INDEX_STATISTICS
Processing object type SCHEMA_EXPORT/TABLE/STATISTICS/TABLE_STATISTICS
Processing object type SCHEMA_EXPORT/DEFAULT_ROLE
Processing object type SCHEMA_EXPORT/PRE_SCHEMA/PROCACT_SCHEMA
