UDEV rules for device persistency-ownerships in REDHAT 6.1 for ASM | Oracle Data base Administration Oracle Database AdministrationUma M Katru blog about Oracle Database Home About Home > Linux > UDEV rules for device persistency-ownerships in REDHAT 6.1 for ASM UDEV rules for device persistency-ownerships in REDHAT 6.1 for ASM September 5, 2011 ukatru454 Leave a comment Go to comments In linux ASMLib is used to make sure device persistency and ownership after a reboot.UDEV is another alternative to ASMlib to achieve device persistency and ownership on devices. This article outlines the steps that are required to establish device persistency and setup new device names with desired permissions and ownership in REDHAT6.1 using udev. Universally Unique Identifiers (UUIDs) are a standardized method for identifying computers and devices in distributed computing environments. This section uses UUIDs to identify iSCSI, SRP, or Fibre Channel LUNs. UUIDs persist after restarts, disconnection and device swaps. The UUID is similar to a label on the device. [root@dbsl2001 etc]# cat redhat-release Red Hat Enterprise Linux Server release 6.1 (Santiago) Single path configuration Edit the /etc/scsi_id.config file. Add the following line: options=Cwhitelisted Creplace-whitespace To display the UUID for a given device run the scsi_id Cwhitelisted Creplace-whitespace Cdevice=/dev/sd* command. example: [root@dbsl2001 etc]# scsi_id Cwhitelisted Creplace-whitespace Cdevice=/dev/sdd 14f504e46494c45525971777468462d5a3277382d42727976 Verify the UUID output from the scsi_id Cwhitelisted Creplace-whitespace Cdevice=/dev/sd* command is correct and as expected. Create a rule to name the device. Create a file named 20-names.rules in the /etc/udev/rules.d directory. Add new rules to this file. All rules are added to the same file using the same format. Rules follow this format: KERNEL==sd*, SUBSYSTEM==block, PROGRAM=/sbin/scsi_id Cwhitelisted Creplace-whitespace /dev/$name, RESULT==UUID, NAME=devicename,OWNER=, GROUP=,OS group>, MODE=0660? Replace UUID and devicename with the UUID retrieved above, and a name for the device. This is an example for the rule above for three example iSCSI luns: KERNEL==sd*, SUBSYSTEM==block, PROGRAM=/sbin/scsi_id Cwhitelisted Creplace-whitespace /dev/$name, RESULT==14f504e46494c45525971777468462d5a3277382d42727976, NAME=asm1,OWNER=grid,GROUP=dba,MODE=0660 [root@dbsl2001 rules.d]# udevadm test /block/sdd [root@dbsl2001 rules.d]# start_udev Starting udev: [ OK ] Check the names, ownerships and permissions of the devices. [root@dbsl2001 rules.d]# ls -la /dev/asm* brw-rw-. 1 grid disk 8, 49 Sep 5 00:20 /dev/asm1