[lustre-discuss] No ZFS compression on OST's when using PFL

[Andreas Dilger]

You are changing a number of different things with each of your tests, not just Lustre.  It could be ZFS 2.1.5->2.1.15 or Alma 8.6->8.10 is also causing issues...  Hard to say for sure without apples-to-apples comparisons.

It should be possible to build Lustre 2.15.5 on Alma 8.6 + ZFS 2.1.5 to help isolate the issue.

There was LU-19193<https://jira.whamcloud.com/browse/LU-19193> filed recently about ZFS and blocksize detection, which might hurt ZFS compression, but that was never landed on 2.15.

Cheers, Andreas

On Aug 1, 2025, at 06:33, BALVERS Martin via lustre-discuss <lustre-discuss at lists.lustre.org> wrote:

I ended up installing lustre 2.15.1 on the new servers. Now compression works as expected when PFL is enabled.

What I have tested so far is:
AlmaLinux 9.4 - Lustre 2.16.1 - ZFS 2.1.16 - No compression with PFL
AlmaLinux 8.10 - Lustre 2.15.7 - ZFS 2.2.8 - No compression with PFL
AlmaLinux 8.10 - Lustre 2.15.5 - ZFS 2.1.15 - No compression with PFL
AlmaLinux 8.6 - Lustre 2.15.1 - ZFS 2.1.5 - PFL + compression works as expected

I tried installing 2.15.2, 2.15.3 and 2.15.4 but that failed with ksym errors.

It seems that somewhere between lustre 2.15.1 and 2.15.5 the PFL + compression breaks.

gr,
Martin Balvers

Cheers, Andreas
—
Andreas Dilger
Lustre Principal Architect
Whamcloud/DDN




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