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

[BALVERS Martin]

Hi,

My initial copy from old lustre to new lustre was with rsync, using this syntax:
SOURCE="/lustre/workgroups" DEST="${SOURCE#/lustre/}" && find "$SOURCE" -maxdepth 1 -mindepth 1 -type d | xargs -t -n1 -P6 -I% rsync -aPA --delete-during % "/mnt/lustre_new/$DEST"

I do indeed need to copy the linux ACL's

But when debugging the issue, I used files without any extended attributes, from other filesystems than lustre.
Just enabling DoM with "lfs setstripe -E 1M -L mdt -E -1 -c 1 /mnt/lustre_new/dom" will disable compression on the OST's. (dom_stripesize is set to 1048576)

I'm thinking about trying 2.15.1 on the new servers...

Regards,
Martin Balvers


________________________________
From: Vicker, Darby J. (JSC-EG111)[Jacobs Technology, Inc.] <darby.vicker-1 at nasa.gov>
Sent: Monday, July 28, 2025 16:57
To: BALVERS Martin <Martin.BALVERS at danone.com>; lustre-discuss <lustre-discuss at lists.lustre.org>
Subject: Re: [EXTERNAL] [BULK] [lustre-discuss] No ZFS compression on OST's when using PFL

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I’m not sure if this is related to your problem but you need to be careful when copying data between two lustre filesystems.  If you use something that copies the extended attributes (e.g. rsync -X), you can copy the lustre xattrs, which is probably not what you want.  This will override the PFL you have on the new lustre FS.  You can either not copy the extended attributes (which isn’t a great option if you are using ACL’s or other xattrs) or use a lustre-aware tool like mpifileutils.



From: lustre-discuss <lustre-discuss-bounces at lists.lustre.org> on behalf of BALVERS Martin via lustre-discuss <lustre-discuss at lists.lustre.org>
Date: Friday, July 25, 2025 at 7:07 AM
To: lustre-discuss <lustre-discuss at lists.lustre.org>
Subject: [EXTERNAL] [BULK] [lustre-discuss] No ZFS compression on OST's when using PFL

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Hi,



I am using a lustre 2.15.1 cluster with PFL. I'm using the following layout:

lfs setstripe -E 1M -L mdt -E 128M -c 1 -S 4M -E 2G -c 2 -z 64M -E -1 -c -1 -z 256M /lustre



OST's have zpools with zstd compression enabled.

This has worked fine for me for many years.



I now have new servers and installed 2.16.1 on them. I used the same PFL layout, and after some benchmarking I proceeded to copy data from the old lustre to the new.

After a while I noticed that it was filling up faster that expected, and say that the compression ratio on the zpools was 1.



Compression on the zpools is enabled, it should have worked as far as I can tell.

When I disable PFL, compression works as expected.



I have attached the some results in a txt file.



I have also tried 2.15.7 with the same results. Enabling PFL, or just DoM disables compression on the OST's.



Am I missing something obvious here?



Regards,

Martin Balvers

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