[DRBD-user] Do You Always Have to Upgrade/Rebuild DRBD Whenever You Upgrade the Kernel?

[Eric Robinson]

> -----Original Message-----
> From: drbd-user-bounces at lists.linbit.com <drbd-user-
> bounces at lists.linbit.com> On Behalf Of Roland Kammerer
> Sent: Tuesday, April 19, 2022 1:55 AM
> To: drbd-user at lists.linbit.com
> Subject: Re: [DRBD-user] Do You Always Have to Upgrade/Rebuild DRBD
> Whenever You Upgrade the Kernel?
>
> On Mon, Apr 18, 2022 at 09:43:38PM +0000, Eric Robinson wrote:
> > New kernel versions are released fairly often. What are the rules
> > about upgrading DRBD when that happens? Is it always necessary, or are
> > there certain thresholds within which it is okay to upgrade the kernel
> > without rebuilding DRBD? Rebuilding DRBD every time is pretty
> > disruptive.
>
> "depends", but in general that is how things work, there are no stable kABI
> guarantees from the Linux kernel itself. So you have to rebuild external
> modules. This is for example why dkms exists.
>
> In more detail it depends on the distribution. RHEL guarantees a stable kABI
> for certain symbols. Unfortunately sometimes even they make mistakes and
> break it, but one usually gets away with relatively few builds. Debian tries to
> keep a stable kABI, Ubuntu does not seem to do so.
>
> Needless to say that we for example test for new RHEL kernels and compat
> and provide new binary modules for our customers. They just upgrade and
> don't have to worry. Same for Debian - we build when we need to - we build
> every Ubuntu kernel release. For the other distros it depends on their model
> (which roughly depends on how "good" their RHEL clone actually is). Even
> with rotating out old kernels rather quickly, we get
> 3 figure kernel numbers we build for easily.
>
> Regards, rck
> ____

Thanks for the feedback, Roland. I am actually a paying Linbit customer, but I am unaware of the process to follow when upgrading the OS. For example, I'm currently running Rocky Linux 8.5 (kernel 4.18.0-348.2.1.el8_5.x86_64) and drbd 9.19.1-1.el8. There is a kernel upgrade to 4.18.0-348.20.1.el8_5 available in the Rocky repo. If I install that, does it break drbd? If so, are you saying that I should do a rolling upgrade of drbd on my cluster?

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