Re: [HTCondor-users] Upgrading the cluster piecemeal instead of big bang

[Cole Bollig <cabollig@xxxxxxxx>]

Hi Dennis,

We try our best to not break communications between versions but guarantee interoperability between the current (v25) and the previous (v24) major versions that are being supported. Note there is the caveat of some functionality newer functionality not being available if said feature requires changes on multiple parts (i.e. AP and EP). We, the CHTC, actually make sure to test interoperability in our local pool by having an older version set up. Otherwise most of our pool is running the most recent unreleased Alpha or Beta version for testing purposes (since we develop HTCondor).

As for upgrade order, it shouldn't matter, but I believe we upgrade our CM first and do the rest is waves.

Cheers,

Cole Bollig

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From: HTCondor-users <htcondor-users-bounces@xxxxxxxxxxx> on behalf of Dennis van Dok <dennisvd@xxxxxxxxx>
Sent: Tuesday, March 3, 2026 5:38 AM
To: HTCondor-Users Mail List <htcondor-users@xxxxxxxxxxx>
Subject: [HTCondor-users] Upgrading the cluster piecemeal instead of big bang

 

Hi,

we are still running 24.x on our Grid cluster, planning to upgrade to 25.0.

Is it feasible to upgrade the cluster bit by bit instead of doing a Big
Bang upgrade?

My idea is to upgrade the worker nodes first. If there is no change in
communication protocol, these should still be able to accept work from
the schedds and communicate classads with the central manager.

The four schedds could be done one by one, so we do not have to drain
the entire system.

Only the central manager is a single machine, but it can go down for a
few minutes without affecting running jobs, so impact should be minimal
(no new jobs will be negotiated during that upgrade).

Is this a bad idea? Is there a better order for doing the upgrade? How
do people generally approach these upgrades?

I did look for some guidance in the documentation but found nothing
about running in a mode where versions got mixed.


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