DRBD and kernel upgrades

A question I recently got from our friends at MySQL:

When speaking about DRBD, we mention that if you upgrade your Linux kernel, it is important that you also upgrade the version of DRBD appropriately.
Question: When upgrading the kernel via yum/yast, does it automatically detect that you should also upgrade your DRBD module?

The answer is, as always, a clear and resounding “it depends.” 🙂
Let’s break this down by distribution.

• If you’re on Debian and updating your linux-image package, dpkg will complain about an unresolved dependency from the DRBD kernel module package, forcing you to update that as well.
• If you’re on Debian and adding a more recent linux-image package, it’s up to you to remember to install a new DRBD kernel module package as well.
• If you’re on Debian using the drbd8-module-source package, module-assistant a-i drbd8 is your friend.
• If you’re on SLES, due to extra Requires flags in the SLES RPM package, updating your kernel image will fail unless your drbd-km package is updated as well.
• For other RPM-based distributions such as RHEL or Fedora, again, it’s up to you to install a new drbd-km package.

We’re currently working on getting sensible kernel dependency into our non-SLES RPMs as well.

Bottom line, in any event: when you upgrade your kernel, it’s generally a good idea to manually double-check your DRBD kernel module package dependencies.