Re: Best use of a small SSD with LVM

["Brian J. Murrell" <brian@interlinx.bc.ca>]

On Thu, 2025-08-07 at 11:21 -0400, John Stoffel wrote:
> > > > > 
> 
> This looks interesting, but why isn't it upstreamed into the linux
> kernel?  What's stopping it being added if it's so good?

See my other reply in this thread about that:

https://lore.kernel.org/linux-lvm/eb048b63ab9ecc6aba533a932bf6ff2ed87701f8.camel@interlinx.bc.ca/

Specifically the link to the exact same question I asked of the Open-
CAS developers:

https://github.com/Open-CAS/open-cas-linux/discussions/1605

They list a number of reasons.

Ultimately it still means more work to update kernels from the distro.
And more work typically introduces delays into updating until you have
the time for the extra processing needed to update the Open-CAS kernel
driver as well as your kernel.  :-(

Although, I suppose most directly that's a lack of support for Open-CAS
in a distribution rather than in the upstream kernel.

Ultimately it needs automating in some way such that when your distro
publishes a new kernel package a rebuild of Open-CAS('s kernel module
RPM) for that new kernel is kicked off and an RPM is published in a
repo your servers are subscribed to in order to automatically get that
new kernel module when your distro gets a new kernel.

Quite doable.  Fortunately the Open-CAS project includes a make target
to build an RPM, but it builds to the currently installed kernel, not
the one that you are going to be installing in your update.  It also
requires lots of development tools, etc. on the target system to be
installed.

Alternatively, I have a patch (that I need to submit to Open-CAS) that
I spent a few hours working on last night that let's you specify an
alternate kernel version (i.e. the one in the updates repo that you
want to update to) and builds the Open-CAS RPMs in a mock chroot for
that kernel.  Simply have a process to scoop the result of that build
up and put it into a repo and you have automated Open-CAS updates ready
when you want to update the kernel.

The one missing piece is triggering all of that on the newly available
kernel update in the distro's upstream repos.  Fedora has some neat
tooling (anitya, fedbus, etc.) for that kind of triggering but other
distros do not sadly.

But this is starting to get far afield from LVM so maybe better just
end this discussion there.

Cheers,
b.