[lustre-discuss] Versioning compatibility between userland utilities and kernel modules

[Patrick Farrell]

We don't have any explicit guarantees, no, but we're careful about changes and try not to break older user utilities.

In practice:
The userland utilities should not break across minor updates (within the same release, eg 2.15 to 2.15.1 to 2.15.2), and we try to make sure the userland utilities do not break across major version updates, but in practice this is not well tested and there have been some issues.

So it's still best practice for Lustre to keep user utilities and kernel modules in sync, but if you don't upgrade userspace within a release stream, problems should be unlikely.  Between major releases you should update userspace, as there are likely to be at least some corner case issues.

Patrick Farrell
Lustre Architect, TLC

Get Outlook for iOS<https://aka.ms/o0ukef>
________________________________
From: lustre-discuss <lustre-discuss-bounces at lists.lustre.org> on behalf of Julián Espina Del Ángel via lustre-discuss <lustre-discuss at lists.lustre.org>
Sent: Friday, 04 September 2026 19:01:19
To: lustre-discuss at lists.lustre.org <lustre-discuss at lists.lustre.org>
Subject: [lustre-discuss] Versioning compatibility between userland utilities and kernel modules

Hello! I have a quick question about the version compatibility between the userland utilities and the kernel modules.

According to the wiki, you can perform a rolling update of a cluster if the version you're trying to upgrade to is a newer patch release within the same minor version. However, this assumes the userland utilities and the kernel modules are upgraded simultaneously. My question is: are there any compatibility guarantees when upgrading the kernel modules independently from the userland utilities? Can I upgrade the kernel modules to the next patch version without upgrading the userland utilities? What about if I'm upgrading to the next minor version?

Best regards,
José Julián Espina
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.lustre.org/pipermail/lustre-discuss_lists.lustre.org/attachments/20260905/8c91b166/attachment.html>