[DRBD-user] Updating Kernel w/out Updating DRBD

[Eric Robinson]

> From: Veit Wahlich [mailto:cru.lists at zodia.de]
> Sent: Friday, June 22, 2018 12:45 AM
> To: Eric Robinson <eric.robinson at psmnv.com>
> Cc: drbd-user at lists.linbit.com
> Subject: Re: [DRBD-user] Updating Kernel w/out Updating DRBD
> 
> Hi Eric,
> 
> if your distro is el (e.g. RHEL/CentOS/Scientific), the kernel ABI
> *should* not change during kernel updates, and copying modules from older
> kernel versions as "weak updates" is not uncommon, following the slogan "old
> module is better than no module". This is for example the case for CentOS 7
> and worked quite well in the past, unfortunately with upgrade to 7.5 the ABI
> changed nevertheless and caused many systems even to crash when using
> some old modules, including drbd.
> 
> If you build the module on the system that runs it, you might consider
> installing/building a dkms or akmod package of drbd instead, along with
> dkms/akmod itself. When booting a new kernel, dkms/akmod will check
> whether the packaged modules already exist for the running kernel, and if not,
> they will be built and installed. This works as long as the module source builds
> well against the kernel source/headers provided and all dependencies and build
> tools are present.
> 
> Regards,
> // Veit
> 
> Am Freitag, den 22.06.2018, 04:38 +0000 schrieb Eric Robinson:
> > Greetings -
> >
> > We always build drbd as a KLM, and it seems that every time we update the
> kernel (with yum update) we have to rebuild drbd. This is probably the worlds's
> dumbest question, but is there a way to update the kernel without having to
> rebuild drbd every time?
> >
> > --Eric
> >


I'm familiar with the --with-km switch when building drbd, but I don't see anything in the documentation that allows building an akmod or dkms version instead. How would I do that?

Also, I find it odd that the option to build from source is only in the DRBD 8.3 User Guide and was left out of the 8.4 and 9.X User Guides. (I'm sure the reason is obvious to everyone else I just missed something.) 

--Eric