KVM server: old kernel and old QEMU and libvirt versions?

If I wanna shift from Debian 11 to Rocky on my KVM hypervisor servers (all console) should I worry about the “old” RHEL stable kernel and the old stable versions of QEMU and libvirt related packages?

I know RHEL’s stable kernel 4.18 is getting backported, but I have no clue how much! Is it fully up-to-date compared to e.g. kernel 5.14 when in comes to KVM and storage?
Same question goes for the rather old stable QEMU and libvirt related packages.

Another option could be to actually upgrade the kernel to 5.14 from ELRepo. But maybe the stable 4.18 is backported so heavily that is actually performs better than 5.14?

(I assume RHEL’s and Rocky’s kernel and packages are 99,99% identical)

You would most likely need to check the differences between libvirt version 6 and 7 and qemu 4.2 and 5.2 to see if any issues will occur or might not run due to compatibility problems in the VM configuration files, etc. Rocky has libvirt 6 and qemu 4.2 whereas Debian 11 has libvirt 7 and qemu 5.2.

One good way is make a new server with Rocky, and then copy a vm from your Debian install to the Rocky one and see if it start up and works without problems.

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I’m not to worried about migrating my servers.

But I do see issues using kernel 4.18, both in terms of vital performance and stability.

At first glance I just don’t understand how it make sense to publish a distro running 4.18 in 2021?
On one hand RHEL is the “Flagship” of all distro, an no other company has so many developers and use so many resources improving/optimizing, but still the run a very old kernel and old packages.

Somehow it just don’t make sense. Is RHEL really that “bad” as the version number says, or is it actually state-of-art? I only see it can be, if they do heavily backporting in both kernel and packages?
I’ve tried to find information on how much is backported but couldn’t find much info.

I understand that old version might equal “stability”.

But I see more issues with old packages that have bugs which are only fixed in newer versions, which are not available in the stable/official repositories.

Red Hat does backport to RHEL: Security Backporting Practice - Red Hat Customer Portal

How much features? Don’t know. I’ve seen a feature in GCC and nftables (introduced in 3.13) in kernel of RHEL 7 (which originated as fork of 3.10).

RHEL 8 (released 2019) did cherry-pick content from Fedora 28 (released 2018). The idea of “stable” in RHEL is that you could have set up a service in May 2019 and it can run until 2029 without modifications.

While such stable isn’t same as “does not crash every day” stability, it would be quite worthless if it did not provide some of the latter.

@MrCal you would want to compare it more with Debian 10 than Debian 11. As @jlehtone said, RHEL was released 2019, Debian 10 also has a 4.19 kernel, so pretty much the same. Debian also isn’t great when it comes to having new packages. It was hoped that Debian 11 would have PHP 8 and yet it got PHP 7.4. Debian 10 had PHP 7.3. So not a real great difference.

RHEL or even Debian never really had the newest packages, as they are deemed for stable use. Bleeding-edge distros which have the latest packages, Fedora for example, or running Debian Unstable/Sid which I did once. But then one day Libreoffice didn’t work with a certain function, and then a day or two later, it was fixed. Had that been important for my day-to-day job to do documents, I would have had a problem. Hence stable distros, with older packages. They just work, maybe not the fastest or newest, but good enough for everything.

I think you don’t worry about that, I use Redhat, Debian and Fedora installed KVM/qemu with libvirtd service and it’s working normally and perfectly I don’t have complain using them so far,. in My SS Redhat use 4.2 version, Debian use 5.2 version and fedora the most newest package comparre with Debian Bullesye and Redhat use 6.1 version. But I don’t know is that version is really different version or actually the same version but each dev distro repacking the package with their own version, IDK.


You can installed CentOS Linux 8 Advanced Virtualization SIG repository, available in Rocky Extras.

With the lastest update for EL 8.5 you will get access to qemu 7.0.0 and libvirt 7.6.0.

dnf install centos-release-advanced-virtualization ; dnf update

And your VMs will still run smoothly after that :sunglasses:

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Interesting! I’ll take a closer look

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