First thought is did you disable Linux Multipath prior to installing PowerPath?  Steps are noted in the "EMC® Host Connectivity Guide for Linux" available from PowerLink via the following breadcrumb trail:

Home > Support > Technical Documentation and Advisories > Host Connectivity/HBAs > Installation/Configuration

Specifically, the topic of interest is the section: "Disabling Linux Multipath". 

Also, you should be using "_netdev" in /etc/fstab for the mount options for both RHEL 5.x and 6.x.  This is also noted in the "PowerPath Guide for Linux" available from PowerLink via the following breadcrumb trail:

Home > Support > Technical Documentation and Advisories > Software ~ P-R ~ Documentation > PowerPath Family > PowerPath > Installation/Configuration

I agree with Christopher.

regards,

phukon

I could not locate the "Disabling Linum Multipath" section, but I did read through the "Host connectivity guide for Linux", which was under the "Installation/Configuration" link.

I also read the Powerpath configurat guide.

What I have done on both boxes is to edit the /etc/multipath.conf and blacklist all devices:

blacklist {

        devnode "*"

}

and removed the "devices" and "multipath" sections.

I verified that the multipathd does not startup, and attempt to startup multipathd results in "FAILED" message when using the init scripts.

One box boots fine, the other fails to boot and drops directly into the "Repair filesystem" aka single-user mode.

All this happens very early in the boot sequence, during LUN scanning, well before anything in /etc/fstab is examined.

It simply does not find any SAN based luns at all on one box, the other box works fine.

Ive gone through the init scripts, including "sysinit" and they have the same content on both machines.