This note explains how to set udev rule for setting the disk permission on ASM disks in multipath on CentOS/RHEL 6.x. Follow the below steps if you are using multipath and want to set udev rule on multipath device.
1. Determine partitioned alias for target device
# dmsetup ls |grep p1 datap1 (253, 4) ### you would see something similar to this
2. Edit /etc/udev/rules.d/12-dm-permissions.rules file to set the above device ownership as oracle:dba.
# vi /etc/udev/rules.d/12-dm-permissions.rules
# Set permissions for first partition created on a multipath device (and detected by kpartx)
ENV{DM_NAME}=="datap1", OWNER:="oracle", GROUP:="dba", MODE:="660", SYMLINK+="iscsi/oraasm-$env{DM_NAME}"
3. Restart multipathd service.
# service multipathd restart
4. Check if permissions are correct
# ls -l /dev/dm* brw-rw---- 1 root disk 253, 0 Apr 15 19:40 /dev/dm-0 brw-rw---- 1 root disk 253, 1 Apr 15 19:40 /dev/dm-1 brw-rw---- 1 root disk 253, 2 Apr 15 21:47 /dev/dm-2 brw-rw---- 1 root disk 253, 3 Apr 15 21:47 /dev/dm-3 brw-rw---- 1 oracle dba 253, 5 Apr 15 21:47 /dev/dm-4
5. Verify if oracle ASM symbolic links exists for multipath devices.
# ls -l /dev/iscsi/* lrwxrwxrwx 1 root root 7 Apr 15 21:47 /dev/iscsi/oraasm-datap1 -> ../dm-4