Oracle 11.2 RHEL 6 VMware and ASMlib

If you need to install Oracle 11.2 into RHEL 6 VMware servers you face problems with Oracle ASMlib.
ASMlib is not supported anymore with RHEL 6. Oracle recommends that you use Oracle Unbreakable Linux because it's support ASMlib. And that is not bad choice at all.

But if you need to stick with RHEL 6 then you have to do it without the ASMlib. And you can do it with udev rules. If you are not using VMware you can use also multipath choice but with VMware you need to use udev.

I assume here that all disk are already added into the needed virtual machines.

First you have to enable scsi id's from VMware. If you don't do this you does not see disks id's in RHEL.
Shutdown virtual machine and do the following  (this needs to be done all servers if you are installing RAC)go to the Options tab --> select the Advanced -> General on the left and click the Configuration Parameters button. --> Click the Add Row button and add disk.EnableUUID with value true --> Ok --> reboot Virtual machines

More info about SCSI UUID's from here:
http://diznix.com/2011/05/21/the-case-of-vmware-and-the-missing-scsi-id/

Then create udev rules to find the disks and to create symlinks to them (this needs to be done all servers if you are installing RAC):
Create file /etc/udev/rules.d/99-oracle-asmdevices.rules

File can look like this (in PROGRAM you fetch the SCSI_id which should match the correct disk RESULT value. And SYMLINK creates accepted symlink for the disk.) :

# crs
KERNEL=="sd*1", BUS=="scsi", PROGRAM=="/sbin/scsi_id -g -u --device=/dev/$parent /dev/$name", RESULT=="36000c29de840f074b4c0ecd97719d3c0", OWNER="oracle", GROUP="dba", MODE="0660", SYMLINK+="sdASMcrs"
# data
KERNEL=="sd*1", BUS=="scsi", PROGRAM=="/sbin/scsi_id -g -u --device=/dev/$parent /dev/$name", RESULT=="36000c29d5b7c9a2cf306acf4dbc2d6de", OWNER="oracle", GROUP="dba", MODE="0660", SYMLINK+="sdASMdata"
# arch
KERNEL=="sd*1", BUS=="scsi", PROGRAM=="/sbin/scsi_id -g -u --device=/dev/$parent /dev/$name", RESULT=="36000c29051374180400e5599ae556288", OWNER="oracle", GROUP="dba", MODE="0660", SYMLINK+="sdASMarch"
.
.
.

Last reboot the servers and check that disks are visible correctly in all of them and start the installation.