Create ACFS on Oracle Exadata for Database Migration (Step-by-Step DBA Guide)

In many Oracle database migration projects—especially when moving from IBM POWER, HP Itanium, or other non-x86 platforms—DBAs often need temporary high-capacity storage for Data Pump dumps, RMAN backups, or staging data.

Exadata provides an excellent solution using the Disk Group, which can be quickly converted into a mountable ACFS (ASM Cluster File System) volume.

ACFS on Exadata is widely used in real-world migrations for fast, scalable, and cost-effective temporary storage.

Why Use ACFS on Exadata for Migration?

• No need for additional storage or SAN
• Uses existing Any Disk Group Or Create New Disk Group (highly available)
• ACFS provides POSIX-compliant filesystem
• Can be shared via NFS
• Easy to create and remove

Prerequisites

• Login as grid user
• Any disk group must have enough free space (In Our Case We rae using RECOC1 Disk Group)
• ASM instance must be running
• Root access required for filesystem operations

Step 1: Create ACFS Volume in ASM And Verify Volume Creation

[grid@ORACLEDBASECRETS01 ~]$./ASMDU.sh

Instances running on ORACLEDBASECRETS01 : +APX1, +ASM1, testserv1

                DiskGroup      Redundancy        Total TB       Usable TB        % Free
                ---------     -----------        --------       ---------        ------
                   DATAC1          NORMAL          324.14            0.88           0
                   RECOC1          NORMAL           36.03           29.18          80

[grid@ORACLEDBASECRETS01 ~]$ls -l /dev/asm
total 0
brwxrwx---. 1 root asmadmin 250,  75777 Apr 13 13:41 acfsvol01-148

[grid@ORACLEDBASECRETS01 ~]$ . oraenv
ORACLE_SID = [grid] ? +ASM1
ORACLE_HOME = [/home/oracle] ? /u01/app/19.0.0.0/grid
The Oracle base has been set to /u01/app/grid

[grid@ORACLEDBASECRETS01 ~]$ sqlplus / as sysasm

SQL*Plus: Release 19.0.0.0.0 - Production on Wed Apr 15 09:50:35 2026
Version 19.28.0.0.0

Connected to:
Oracle Database 19c Enterprise Edition Release 19.0.0.0.0 - Production
Version 19.28.0.0.0

SQL> alter diskgroup RECOC1 add volume acfs_2 size 20T;

Diskgroup altered.

SQL> exit

Disconnected from Oracle Database 19c Enterprise Edition Release 19.0.0.0.0 - Production
Version 19.28.0.0.0

[grid@ORACLEDBASECRETS01 ~]$ls -l /dev/asm
total 0
brwxrwx---. 1 root asmadmin 250, 165377 Apr 15 09:53 acfs_2-323
brwxrwx---. 1 root asmadmin 250,  75777 Apr 13 13:41 acfsvol01-148

Use meaningful volume names like acfs,expdp, staging, or migration for better identification.

Step 2: Create ACFS Filesystem

[grid@ORACLEDBASECRETS01 /]$/sbin/mkfs -t acfs /dev/asm/acfs_2-323
mkfs.acfs: version                   = 19.0.0.0.0
mkfs.acfs: on-disk version           = 46.0
mkfs.acfs: volume                    = /dev/asm/acfs_2-323
mkfs.acfs: volume size               = 21990232555520  (  20.00 TB )
mkfs.acfs: Format complete.
[grid@ORACLEDBASECRETS01 /]$ 

Step 3: Register Filesystem with Clusterware And Start Filesystem

[root@ORACLEDBASECRETS01 /]# /u01/app/19.0.0.0/grid/bin/srvctl add filesystem -d /dev/asm/acfs_2-323 -m /acfs_2 -u oracle -fstype ACFS -autostart ALWAYS
[root@ORACLEDBASECRETS01 /]# /u01/app/19.0.0.0/grid/bin/srvctl start filesystem -d /dev/asm/acfs_2-323

Step 4: Set Ownership, Permissions And Verify Mount

[root@ORACLEDBASECRETS01 /]# chown oracle:oinstall /acfs_2
[root@ORACLEDBASECRETS01 /]# chmod 775 /acfs_2
[root@ORACLEDBASECRETS01 /]# df -h /acfs*
Filesystem                           Size  Used Avail Use% Mounted on
/dev/asm/acfsvol01-148                85T   54T   32T  63% /acfs01
/dev/asm/acfs_2-323                   20T   42G   20T   1% /acfs_2

Check Directory Permissions

[root@ORACLEDBASECRETS01 /]# $ ls -ld /acfs_2/

drwxrwxr-x 4 oracle oinstall 20480 Apr 15 10:08 /acfs_2/

ACFS filesystem is now ready for use. You can store Data Pump dumps, RMAN backups, and migration files.
Always use srvctl for ACFS management
Monitor RECO disk group usage carefully
Do not consume entire RECO (used for FRA/backups)
Test in non-production before implementation
Take backup before performing operations

Exadata ACFS Cleanup: Safely Stop, Remove & Drop ACFS Volume (12c/19c Guide)

During a cross-platform migration from AIX to Exadata, a 25TB ACFS filesystem was created on RECO disk group to store Data Pump files. This eliminated the need for external storage and reduced migration time by 40%.

Key Takeaways

ACFS provides quick and flexible storage on Exadata
No additional hardware required
Easy to create and remove after migration
Ideal for temporary staging and large data movement

Conclusion

ACFS on Exadata is a powerful, zero-cost solution for temporary storage during database migrations. It allows DBAs to quickly provision large storage, use it efficiently, and safely clean it up after use without impacting production workloads. This method is widely adopted in enterprise migrations and is highly recommended for DBAs working on Exadata environments.

Please feel free to ask if you have any questions. Thank you 🙂

Toufique Khan