Comment 34 for bug 220493

Still didn't work automatically for me:
I upgraded my Hardy AMD64 Server installation via apt-get dist-upgrade. After that, there was still only the old module dm-raid4-5.ko in /lib/modules/2.6.24-18-server/ubuntu/md (and yes, I performed at least one reboot, which didn't help).
Only after adding the module from Stefan's PPA manually into that directory, and inserting a line into modules.dep it finally worked.

Package versions currently installed:
linux-image-server is 2.6.24-18.20
linux-ubuntu-modules ist 2.6.24-26
I just upgraded once more, there are no further updates available.