Createing ACFS in ASM

Question

Hi,
I am going to create ACFS filesystem in ASM having 2 node RAC 11.2.0.2.
I could get the option of ASMCA which will create ACFS file system on disk group. Which looks very straight forward.
But when I gone through some docs on ACFS [command line] it says to create the volume first [which is ADVM feature] and then create ACFS using ASMCMD>mkfs. I could not understand the why do we have to create volume in order to create ACFS? Also gone through the ADVM docs but did not understand what exactly it is and how it works?
Is the volume created using ADVM is the logical structure? Becuase when I created volume using ADVM I could not do CD to particular volume.
Can anyone explain the same to clear my fundas.
Thanks...

Answer 1

Hi,
think of ASM as a logical volume manager.
Like with every volume manager, you have to first create a volume, before you can put a filesystem onto it.
It is the same here: You first have to create a volume inside your ASM diskgroup, that this volume gets "exported" to the OS. After you created a volume, you will find a volume under /dev/asm/<name>.
This volume than can be used, to put any filesystem onto it, whatever you want.
E.g. ext3. Or better the ACFS filesystem.
Filesystems are formatted using mkfs (make file system command) from linux.
In the special case of ACFS it is mkfs.ext3 (which by the way is not an asmcmd command, but a generall linux command).
Now if you create ACFS via asmca, then the volume is created under the cover automatically. But if you look you will find the volume listed under the volume tab of ASMCA.
Regards
Sebastian