Home > Storage > PowerFlex > White Papers > Oracle RAC Performance on Dell PowerFlex with AMD EPYC Compute Nodes > Appendix 2. UDEV rules
The UDEV functionality in the Linux operating system allows to give consistent names and permissions across clusters to the devices. The UDEV rules use the SCSI ID of a device to assign an operating system name and permission. Since the SCSI ID of a device does not change, this allows ASM to see a consistent device name across clusters and reboots.
The following example shows a sample configuration file with UDEV rules:
# /lib/udev/scsi_id --page=0x83 --whitelisted --device=/dev/scinia1
205882424d18e110f72ccd7430000000e
# /lib/udev/scsi_id -g -u -d /dev/scinia1
205882424d18e110f72ccd7430000000e
# vi /etc/udev/rules.d/99-asm-devices.rules
KERNEL=="scini*", OPTIONS:="nowatch", SUBSYSTEM=="block", PROGRAM=="/usr/lib/udev/scsi_id -g -u -d /dev/$parent", RESULT=="205882424d18e110f72ccd7430000000e", SYMLINK+="oradata1", OWNER="grid", GROUP="asmadmin", MODE="0660"
# udevadm control --reload-rules
# udevadm trigger
# ls -l /dev/oracleasm/
lrwxrwxrwx 1 root 10 May 5 06:31 oradata1 -> ../scinia1
The Oracle database administrator can now use asmca with a discovery string of /dev/oracleasm/* to locate the devices and create ASM disk groups from them.