During the installation of Oracle 11gR2 on Red Hat Enterprise Linux 5 I stumbled upon a incorrect default setting for ASM disk discovery when using ASM lib. The discovery path is set to ‘/dev/raw/sd*’, which is incorrect because ASM lib creates the devices under ‘/dev/oracleasm/disks’.

Another thing to be aware of is the ownership of the disks. You need to run ‘/etc/init.d/oracleasm configure’ in order to configure the owner. If you just hit return the ownership of the disks is set to root. Because you will start the Oracle installation as user oracle the disks will not appear in the discovery step during the installation.

Incorrect ownership:

ls -l /dev/oracleasm/disks/* brw------- 1 root root 8, 65 Jan 20 15:27 /dev/oracleasm/disks/VOL1 brw------- 1 root root 8, 49 Jan 20 15:27 /dev/oracleasm/disks/VOL2 brw------- 1 root root 8, 33 Jan 20 15:27 /dev/oracleasm/disks/VOL3

Configure Oracle ASM Library:

/etc/init.d/oracleasm configure Configuring the Oracle ASM library driver. This will configure the on-boot properties of the Oracle ASM library driver. The following questions will determine whether the driver is loaded on boot and what permissions it will have. The current values will be shown in brackets ('[]'). Hitting without typing an answer will keep that current value. Ctrl-C will abort. Default user to own the driver interface []: oracle Default group to own the driver interface []: oinstall Start Oracle ASM library driver on boot (y/n) [y]: Scan for Oracle ASM disks on boot (y/n) [y]: Writing Oracle ASM library driver configuration: done Initializing the Oracle ASMLib driver: [ OK ] Scanning the system for Oracle ASMLib disks: [ OK ]

Correct ownership:

ls -l /dev/oracleasm/disks/ total 0 brw-rw---- 1 oracle oinstall 8, 33 Jan 20 15:27 VOL1 brw-rw---- 1 oracle oinstall 8, 49 Jan 20 15:27 VOL2 brw-rw---- 1 oracle oinstall 8, 65 Jan 20 15:27 VOL3

Hope it saves you some time!