I came across the following from the ext3-users mailing list. The poor user was stuck on a never-updated RHEL 3 production server and running into kernel panic problems. He was advised to try updating to the latest kernel rpm from Red Hat, but he didn’t feel he could do that. In his words:
I’m caught between a rock and a hard place due to the EMC PowerPath binary only kernel crack. Which makes it painful to both me and my customers to regularly upgrade the kernel. Not to mention the EMC supportability matrix of doom.
That pretty much sums it all up right there.
The good news is that I’ve been told that dm-multipath is almost at the point where it has enough functionality to replace PowerPath. Of course, that version isn’t yet shipping in distributions, and I’m sure it needs more testing, but it’ll be good when enterprise users who need this functionality can move to a 100% fully open source storage stack.