Requirements for Disk Discovery
There're several requirements for disks to be discovered:
1. Right Device Type
For 11g or later, only block devices leading by letter b in permission notation are acceptable, any others device types, such as character devices, symbolic links (leading by letter l) and pseudo devices are not ASM candidates.
Please see an example of block device in the following content.
2. Proper Permission
If you plan to use grid to install grid infrastructure, then the owner of disks should be grid:asmadmin, not root:root.
[root@primary01 ~]# ll /dev/sdb1
brw-rw---- 1 grid asmadmin 8, 17 Oct 10 12:58 /dev/sdb1
Either using persistent rule of udev or ASMLib can set the permission properly.
3. Compatible sector size
Since release 12.2, ASM disks have to be compatible with the possible combination of physical and logical sector size of disks. In summary, either 512 or 4K is acceptable.
That is to say, ASM does not accept physical sector sizes larger than 4K. But we can work around the restriction by using the logical sector size instead of physical sector size if you're using ASMLib.
4. Correct discovery path
The default path of disks for ASM to discover is /dev/sd*. You can change the discovery path by clicking on Change Discovery Path in grid infrastructure OUI.
For ASMLib, there're two possible paths where ASM can find disk candidates.
You can try above paths one by one.
The 4th point (Correct Discovery Path) worked for me. Thanks a lot.
I’m glad it’s helpful.
Thanks for this blog.
But I am facing issue while installing oracle 12.2 grid.
While selecting ASM disk during installation, it is showing error INS 30515.
Cause – Insufficient space available in the selected Disks. At least, 38,728 MB of free space is required.
Action – Choose additional disks such that the total size should be at least 38,728 MB
But i have given 30gb space ,.
Need your help.
OS – OEL 7.8
GRID – Oracle 12.2
I don’t know about the error, but I guess it might discover the wrong path.
I resolved a similar issue by changing permissions under /dev/oracleasm:
There are hidden files under that directory that were owned by ‘root’:
Changed the ownership to grid:oinstall. Also changed ownership on the IID directory to grid:oinstall (recursive)
Went back to my GRID install and used ORCL:* as Directory Path and the disks showed.
The server was setup by a chef script so I’m not sure how the permissions get set originally.
Thanks for your feedback, it is much appreciated.