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When the host reboots, all devices receive root user permissions by default. However, Oracle ASM storage devices require an Oracle user permission. The permission setting of the Oracle ASM devices must be part of the boot sequence, which is when ASM services start.
Oracle ASMlib and ASM Filter Driver (AFD) set the device permissions automatically. When ASMlib or AFD are not used, using udev rules is the simplest way to set device permissions during the boot sequence.
Udev rules are added to a text file in the /etc/udev/rules.d/ directory. The rules are applied in order based on the index number preceding the file names in this directory.
The content of the text file with the rule involves identifying the Oracle devices correctly. For example, if all PowerPath devices can have Oracle permissions, set a general rule that applies to all such devices. If all devices are not used for Oracle, then the devices must be grouped based on either their WWN or another form of identification.
For example, if a single partition is used on each of the Oracle devices, identify only those devices. While partitions might not be necessary to run Oracle ASM on Linux, they offer a convenient means of assigning Oracle user permissions to all the devices with a partition on the host.
Set Oracle user permissions to all the PowerPath devices with partition 1:
# vi /etc/udev/rules.d/85-oracle.rules
ACTION=="add|change", KERNEL=="emcpower*1", OWNER:="oracle", GROUP:="dba", MODE="0660"
Set Oracle user permissions to all the DM aliases starting with ora_ and using partition 1:
# vi /etc/udev/rules.d/12-dm-permissions.rules
ENV{DM_NAME}=="ora_*p1", OWNER:="oracle", GROUP:="dba", MODE:="660"