Oracle using ASM diskgroup with 4096 sector size (ASMLib)

Hi All,


This is neto from Brazil


How are you?


Here you have a procedure to install and create a database with ASM diskgroups with 4096 sector size.


If you want to use ASMLib please make sure you have the following version and configuration:




GRID install


Checking asm_diskstring (for GRID install)

Diskgroup with 512 sector size because it's using /dev/mapper on the asm_diskstring

Create a diskgroup CONF with the string /dev/mapper (512 bytes) to store your spfile (spfile must resides in 512 bytes diskgroup)



Preparing the asm_diskstring to have ORCL:* and /dev/mapper (with the specific disks for GRID and CONF diskgroups)

Change asm_diskstring in the file and recreate the spfile as: create spfile='+GRID' from pfile='/home/grid/spfile-neto.ora';


After adding the ORCL:* string and create the diskgroups.

Using DBCA, the installer will try to create the spfile on the same diskgroup as datafiles and it will fail (because it's 4096 bytes).


Please don't click finish on DBCA, save the scripts, modify the spfile to +CONF diskgroup.



After to make all changes to '+CONF', please execute the script:


Database has been created with success.



All the best



NetApp - I love this company!

on ‎2013-10-16 04:09 AM

Dear Neto,

thanks a lot for this article. We are currently running into the problem, that our asmlib (exactly the version you are using in this article) does not accept LUNs provided by a FAS 3270 (Ontap 8.1.2 7-mode) with a physical sector size of 4k. Therefore we also have the problem that we cannot put our spfile in a 512 byte diskgroup as our FAS 3270 only provides LUN with a physical sector size of 4k.

Due to compatibility issues we cannot update to Ontap 8.1.3 to use the command "lun set report-physical-size <path> disable" to fix this issue.

Our target configuration is RHEL 6.4, Oracle as RAC, using asmlib in combination with SnapDrive and SMO.

Do you have any idea how we can get this running?

Thanks a lot,