Creating an ACFS filesystem

Cyrille Modiano
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About ACFS filesystem

ACFS mean  Automatic Storage Management Cluster File System. This filesystem volume resides inside the ASM database and can be used to store database files but also any type of files with or without direct relation to the database.

Oracle ACFS does not support Oracle Grid Infrastructure or Oracle Cluster Registry voting files.

The ACFS filesystem can be extended dynamically without any service interruption, you just need to add space to the diskgroup hosting the ACFS volume and then extend the filesystem.

Creation Steps


Creating the diskgroup

As the filesystem is hosted in ASM we need to create a new diskgroup which will be used to host the filesystem. You can obviously use an existing Disk Group but I would recommend to create a separate one.

asmca -silent -createDiskGroup -diskGroupName BACKUP -diskList '/dev/asmbck*' -redundancy EXTERNAL -au_size 4

This command will create a DiskGroup named BACKUP which will use any disk found in /dev and starting with name asmbck, the external redundancy mean that redundancy will not be managed by ASM but by the device hosting the disk.

Create the Volume

Next we will need to create a volume for the filesystem

asmcmd volcreate -G BACKUP -s 1T --redundancy unprotected asmbck01

In this command we create a volume in the DiskGroup BACKUP with size 1TB named asmbck01. Of course the size you specify in the command should be inferior or equal to the space available in the Disk Group.

To see the name of the device created, you can use the following command:

asmcmd volinfo -G BACKUP asmbck01

Diskgroup Name: BACKUP

         Volume Name: asmbck01
         Volume Device: /dev/asm/asmbck01-367
         State: ENABLED


Create the FileSystem

/sbin/mkfs -t acfs /dev/asm/asmbck01-367

Not much to say about this step, we just invoke the mkfs binary saying we want to create an ACFS filesystem with the name of the volume previously created.

Register the new FileSystem with Oracle Clusterware

This step is not mandatory but recommended, it will add the new filesystem as a Clusterware resource. This means that Clusterware will be responsible for mounting the filesystem on all available nodes.

/sbin/acfsutil registry -a /dev/asm/asmbck01-367 /u10

Once mounted, you can change the ownership to the oracle user.

chown -R oracle:dba /u10

For more information, you can see the documentation here: Creating an Oracle ACFS File System

That’s it !

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