You need to disable native multipathing and boot into the WO ram disk first before the PowerPath install. . Note it is in the boot from san section but still applies. See page 38 of the linked guide.

https://support.emc.com/docu56668_PowerPath-for-Linux-6.0-Installation-and-Administration-Guide.pdf

From the guide..

Disabling dm-multipath on

a RHEL 6.x or OL 6.x host

1. Blacklist all devices in /etc/multipath.conf

a. Save a copy of /etc/multipath.conf as

/etc/multipath.conf.bak for backup if it

already exists.

b. Edit /etc/multipath.conf so that it contains only the following lines:

blacklist {

devnode "*"

}

2. Ensure dm-multipath does not start automatically at boot.

# chkconfig multipathd off

# chkconfig --list multipathd

  -- - -Service should be off on

all run levels

3. Recreate initramfs so that dm-mul

tipath is excluded from initramfs.

# dracut /boot/initramfs-wo-DM-$(uname -r).img $(uname -r)

4. Add a new boot entry with the initramfs file created in previous step in the

/boot/grub/menu.lst file.

5. Reboot the host with the new initramfs im

age and ensure dm-multipath does not have

any devices configured.

# multipath -ll

  --- should not return any dm devices

After you boot into the new ram disk you will then do the PowerPath install and lvm configuration per the guide..