Not able to install rhel 9 on ganeti

[tshul...@gmail.com]

Hi,  

When I tried to isntall rhel 9 on ganeti,  I ended up with follow issues.

Anybody please help.

Thanks 

[Martin McClure]

Hi,

I don't know specifically recognize this error screen, but rhel 9 has a requirement for certain newer CPU features, so running with a generic virtual CPU will fail. For KVM, changing the hypervisor parameter cpu_type can fix this.

Regards,
-Martin

[tshul...@gmail.com]

Thank you. If  I am to change the cpu_type , will this is affect existing instances ? or is it possible to change for particular instance ? Thanks,.

[Martin McClure]

On 3/7/23 22:41, tshul...@gmail.com wrote:

Thank you. If  I am to change the cpu_type , will this is affect existing instances ? or is it possible to change for particular instance ? Thanks,.

You can change the default for the cluster, or for the specific instance.

If all nodes in your cluster have the same CPU type, you might benefit by setting the entire cluster's cpu_type to 'host,' which will make all of the instructions of the CPU available to instances, increasing performance for libraries that take advantage of more recent CPU instructions if present.

However, if your cluster has nodes of different ages, doing this could cause problems during live migration, though migrating shut-down instances between nodes will still work fine.

Regards,
-Martin

[tshul...@gmail.com]

Thank you. 

[c sights]

Dang! I discovered all this the hard way just a week ago. :-)

C.

[John McNally]

Tshul,

I have experienced this issue exactly. The problem is that RHEL 9 and "compatible" distros, like Rocky and AlmaLinux, are stricter about CPU type.

The KVM hypervisor allows minute specification of the processor type through its "-cpu" option. In ganeti, you can set this option with the "cpu_type" backend parameter in "gnt-cluster init" or "gnt-cluster modify." For example, to set the CPU type to "IvyBridge", run:

gnt-cluster modify -H kvm:cpu_type=IvyBridge

If the CPU type across all cluster nodes is _not_ the same, pick a type representing the least common denominator, or the type of the oldest CPU in the cluster. If all the CPU's in the cluster are identical (highly recommended for for live migration), then set "cpu_type" to "host", like this:

gnt-cluster modify -H kvm:cpu_type=host

This tells KVM to use the CPU type of the ganeti host for each instance.

Don't worry about your cluster CPUs being too "old" -- I'm running new EL9 instances on 13-year-old Westmere hardware, with no problem. If you spec cpu_type appropriately, it should be fine.

So, cpu_type is the important factor here. Without it, KVM instances will default to "QEMU Virtual CPU version n.n.n" (as seen in /proc/cpuinfo) which is, apparently, unacceptable to the EL9 Linux 5 kernel.

Hope this helps.

  

_________________
John McNally
jmcn...@acm.org

--
You received this message because you are subscribed to the Google Groups "ganeti" group.
To unsubscribe from this group and stop receiving emails from it, send an email to ganeti+un...@googlegroups.com.
To view this discussion on the web visit https://groups.google.com/d/msgid/ganeti/abf886f4-2718-45fd-976f-4807c141fdabn%40googlegroups.com.

[c sights]

This contains a script to check whether your (virtual) CPU is at least x86-64-v2, which is required for EL9.

https://unix.stackexchange.com/questions/631217/how-do-i-check-if-my-cpu-supports-x86-64-v2

To view this discussion on the web visit https://groups.google.com/d/msgid/ganeti/CAJCZBsz1-c8YYLr14hxxcyOatfQWB7ioejT1BXMr0R2R7c2Gpg%40mail.gmail.com.