Do you know that Redhat and Novell handle their boot process completely different?  Yes it’s true, Novell has modularized their boot process into individual files under /etc however Redhat 5 currently handles this in a linear process.  Ok thanks  now I feel smarter, but how does this affect me?  Here’s the deal, third party vendors that need to be leveraged, have to insert their code into the boot process so their modules are loaded and their product is functional.  On a typical Sles machine these files will be inserted into the boot.d structure; however on a Redhat system the code will be injected into rc.sysinit.

Now we get to the core, on Redhat machine who owns the /etc/rc.d/rc.sysinit file, yes you are correct, it is from initscripts.  And this is important because?  Well this is a rpm package that can and will be updated via content, therefore overriding any content that was previously stored.  And then the multipath is broken …

Have no fear however, the solution is a quick fix.  By restarting Powerpath (/etc/init.d/PowerPath start), it will re-inject itself into sysinit, which will provide the mechanism to survive a reboot and allow the modules to be loaded at default and re-enable your file systems depending upon the emc pseudo devices.