How To Create ACFS Mount Point?

July 27, 2025

Creating ACFS Mount Point

Configuration Details

The example commands use the following configuration.

Oracle Clusterware runs on the nodes rkol7rac2a and rkol7rac2b. There are ASM disk groups DATA, FRA and FS. We want to create a new cluster file system on the ASM disk group FS.

Create ASM Volume

ACFS runs on ASM in Oracle Clusterware. Every ACFS is located in Oracle ASM Dynamic Volume. We use asmcmd to create a new volume in ASM. The minimum volume size is 512MB. Le’t create a new 1GB large volume in ASM disk group FS. We will use this volume for configuration files and TDE wallets.

The following commands are executed as grid OS user:

Check the size of FS ASM disk group

grid@rkol7rac2a> asmcmd    
ASMCMD> lsdg FS
State    Type    Rebal  Sector  Logical_Sector  Block       AU  Total_MB  Free_MB  Req_mir_free_MB  Usable_file_MB  Offline_disks  Voting_files  Name
MOUNTED  EXTERN  N         512             512   4096  1048576     20478    19343                0           19343              0             N  FS/

There is enough free space to create a new ASM volume:

ASMCMD> volcreate -G FS -s 1G cfg

Create ACFS

Let’s check the status of the ASM disk volume cfg:

ASMCMD> volinfo -G FS cfg
Diskgroup Name: FS

	 Volume Name: CFG
	 Volume Device: /dev/asm/cfg-459
	 State: ENABLED
	 Size (MB): 1024
	 Resize Unit (MB): 64
	 Redundancy: UNPROT
	 Stripe Columns: 8
	 Stripe Width (K): 1024
	 Usage: 
	 Mountpath:

In the output we can see the device path for this volume: /dev/asm/cfg-459. We use this device to create a new cluster file system (ACFS) on it.

As root OS user:

root@rkol7rac2a ~]# mkfs -t acfs -n cfgfs /dev/asm/cfg-459
mkfs.acfs: version                   = 19.0.0.0.0
mkfs.acfs: on-disk version           = 46.0
mkfs.acfs: volume                    = /dev/asm/cfg-459
mkfs.acfs: volume size               = 1073741824  (   1.00 GB )
mkfs.acfs: Format complete.
[root@rkol7rac2a ~]#

The -n cfgfs options specifies cfgfs name for our new file system.

Add ACFS Mount Point

ACFS is created. Now we have to add mount points on each node. As root OS user create on both nodes a new directory /cfg:

[root@rkol7rac2a ~]# mkdir /cfg
[root@rkol7rac2a ~]# 

[root@rkol7rac2b ~]# mkdir /cfg
[root@rkol7rac2b ~]#

Now we can register this mount point to ACFS.

As root OS user:

[root@rkol7rac2a ~]# /sbin/acfsutil registry -a /dev/asm/cfg-459 /cfg
acfsutil registry: mount point /cfg successfully added to Oracle Registry

We can check the ACFS property of this mount point with the following command as root OS user:

[root@rkol7rac2a ~]# /sbin/acfsutil info fs /cfg
/cfg
    ACFS Version: 19.0.0.0.0
    on-disk version:       49.0
    compatible.advm:       19.0.0.0.0
    ACFS compatibility:    19.0.0.0.0
    flags:        MountPoint,Available,KiloSnap
    creation time:   Sun Jul 27 16:44:43 2025
    mount time:      Sun Jul 27 16:51:42 2025
    mount sequence number: 1
    number of nodes:       2
    allocation unit:       4096
    metadata block size:   4096
    volumes:      1
    total size:   1073741824  (   1.00 GB )
    total free:   496132096  ( 473.15 MB )
    file entry table allocation: 393216
    primary volume: /dev/asm/cfg-459
        label:                 cfgfs
        state:                 Available
        major, minor:          250, 235010
        logical sector size:   512
        size:                  1073741824  (   1.00 GB )
        free:                  496132096  ( 473.15 MB )
        metadata read I/O count:         2096
        metadata write I/O count:        38
        total metadata bytes read:       8806400  (   8.40 MB )
        total metadata bytes written:    540672  ( 528.00 KB )
        ADVM diskgroup:        FS
        ADVM resize increment: 67108864
        ADVM redundancy:       unprotected
        ADVM stripe columns:   8
        ADVM stripe width:     1048576
    number of snapshots:  0
    snapshot space usage: 0  ( 0.00 )
    replication status: DISABLED
    compression status: DISABLED
[root@rkol7rac2a ~]#

ACFS Test

Let’s test this cluster file system as oracle OS user. At first, we have to create a new directory in this mount point and give oracle OS user read and write permissions on it.

As root OS user on the first node:

[root@rkol7rac2a ~]# mkdir /cfg/oracle
[root@rkol7rac2a ~]# chown oracle:oinstall /cfg/oracle
[root@rkol7rac2a ~]# ls -ld /cfg/oracle
drwxr-xr-x 2 oracle oinstall 20480 27. Jul 16:56 /cfg/oracle
[root@rkol7rac2a ~]#

As root OS user on the second node:

[root@rkol7rac2b ~]# ls -ld /cfg/oracle
drwxr-xr-x 2 oracle oinstall 20480 27. Jul 16:56 /cfg/oracle
[root@rkol7rac2b ~]#

We have created a new directory on the first node. The second node is aware of this directory as well. Now we want to create a new file as oracle OS user in this directory:

First node:

oracle@rkol7rac2a> echo "ACFS test"  > /cfg/oracle/test.out
oracle@rkol7rac2a>

Second node:

oracle@rkol7rac2b> cat /cfg/oracle/test.out 
ACFS test
oracle@rkol7rac2b>

ACFS is ready to use on both nodes.

Resize ACFS

Manual Resize

If there is enough space in the ASM disk group, you can resize the ACFS mount point.

We want to change the size of this file system:

[root@rkol7rac2a ~]# /sbin/acfsutil info fs /cfg
/cfg
    ACFS Version: 19.0.0.0.0
...
    allocation unit:       4096
    metadata block size:   4096
    volumes:      1
    total size:   1073741824  (   1.00 GB )
    total free:   429023232  ( 409.15 MB )
...

We can increase the size by 128MB:

[root@rkol7rac2a ~]# /sbin/acfsutil size +128M /cfg
acfsutil size: new file system size: 1207959552 (1152MB)

[root@rkol7rac2a ~]# /sbin/acfsutil info fs /cfg
/cfg
    ACFS Version: 19.0.0.0.0
...
    allocation unit:       4096
    metadata block size:   4096
    volumes:      1
    total size:   1207959552  (   1.12 GB )
    total free:   562974720  ( 536.89 MB )
...

Automatic Resize

You can use -a IncrementSize option to automatically resize the ACFS by the specified increment. In such a case you should use -x MaximumSize option as well to set the maximum size of this file system.

Enable automatic resize:

[root@rkol7rac2a ~]# /sbin/acfsutil size -a 64M -x 2048M /cfg
acfsutil size: ACFS-03641: auto-resize increment below minimum 1G

Apparently we should increase the increment from 128MB to 1GB:

root@rkol7rac2a ~]# /sbin/acfsutil size -a 1G -x 2048M /cfg
acfsutil size: ACFS-03642: successfully updated auto-resize settings
[root@rkol7rac2a ~]#

Let’s check automatic resize properties of this file system:

[root@rkol7rac2a ~]# /sbin/acfsutil info fs /cfg
/cfg
    ACFS Version: 19.0.0.0.0
...
    total size:   2147483648  (   2.00 GB )
    total free:   1500635136  (   1.40 GB )
    auto-resize increment:   1073741824  (   1.00 GB )
    auto-resize maximum:     2147483648  (   2.00 GB )
...

We don’t need automatic resize for this file system. So we disable this now:

[root@rkol7rac2a ~]# /sbin/acfsutil size -a 0 /cfg
acfsutil size: ACFS-03642: successfully updated auto-resize settings
[root@rkol7rac2a ~]# 

[root@rkol7rac2a ~]# /sbin/acfsutil info fs /cfg
/cfg
    ACFS Version: 19.0.0.0.0
...
    total size:   2147483648  (   2.00 GB )
    total free:   1500635136  (   1.40 GB )
...

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