ASM instance: ORA-15032 and ORA-15063 errors occur after restart of the Host

We already had the same symptom of ORA-15032 & ORA-15063 mentioned in my last post. Trying to follow these instructions didn't help this time.

ls -l /dev/oracleasm/disks/*
rpm -qa | grep oracleasm
kfod asm_diskstring='ORCL:*' disks=all
/etc/sysconfig/oracleasm conatin ORACLEASM_SCANORDER=dm
spfile has: asm_diskstring = /dev/dm*

All of these command worked fine. Beacause of the dm* parameter I checked the filesystem:

$ ls -l /dev/dm-*
/bin/ls: /dev/dm-*: No such file or directory

It seems that the dm* devices are missing and must be there for ASM by Note 602952.1 :

NOTE: When scanning, only the device names known by the kernel are scanned. With device-mapper, the kernel sees the devices as /dev/dm-XX. The /dev/mapper/XXX names are created by udev for human readability. Any configuration of ORACLEASM_SCANORDER or ORACLEASM_SCANEXCLUDE must use the dm prefix.

Since this Host is RedHat 5, we found the source of the problem by Note 558596.1:

Cause: The oracleasm scans /proc/partitions and expects devices to be available in /dev. If the device doesn't exist in /dev it will fail to open the device. RHEL/OEL5 does not create dm-xx devices in /dev by default.
Solution: Please comment out the following line in file /etc/udev/rules.d/50-udev.rules
#KERNEL=="dm-[0-9]*", ACTION=="add", OPTIONS+="ignore_device"
reboot and the problem should be gone.
Note: Newer versions of EL/RH 5 the udev rule has been moved to "/etc/udev/rules.d/90-dm.rules".