[lustre-discuss] No ZFS compression on OST's when using PFL
BALVERS Martin
Martin.BALVERS at danone.com
Fri Aug 1 05:33:34 PDT 2025
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
AlmaLinux 8.6 - Lustre 2.15.1 - ZFS 2.1.5
[root at microbio pfl]# ls -lh *
-rw-r--r-- 1 root root 6.3G Jul 1 13:28 test1.txt
-rw-r--r-- 1 root root 6.3G Jul 23 09:34 test2.txt
-rw-r--r-- 1 root root 6.3G Jul 23 09:35 test3.txt
LUSTRE:SVNAME COMPRESS NAME RATIO REFRATIO USED LUSED
lustre-MDT0000 zstd-fast mdt/mdt 1.51x 1.51x 8.23M 6.80M
lustre-OST0000 zstd lustre/ost 4.60x 4.60x 1.37G 6.29G
lustre-OST0001 zstd lustre/ost 4.60x 4.60x 1.37G 6.29G
lustre-OST0002 zstd lustre/ost 4.60x 4.60x 1.37G 6.29G
[root at microbio pfl]# lfs getstripe test1.txt
test1.txt
lcm_layout_gen: 40
lcm_mirror_count: 1
lcm_entry_count: 5
lcme_id: 1
lcme_mirror_id: 0
lcme_flags: init
lcme_extent.e_start: 0
lcme_extent.e_end: 1048576
lmm_stripe_count: 0
lmm_stripe_size: 1048576
lmm_pattern: mdt
lmm_layout_gen: 0
lmm_stripe_offset: 0
lcme_id: 2
lcme_mirror_id: 0
lcme_flags: init
lcme_extent.e_start: 1048576
lcme_extent.e_end: 134217728
lmm_stripe_count: 1
lmm_stripe_size: 4194304
lmm_pattern: raid0
lmm_layout_gen: 0
lmm_stripe_offset: 0
lmm_objects:
- 0: { l_ost_idx: 0, l_fid: [0x100000000:0x6e:0x0] }
lcme_id: 3
lcme_mirror_id: 0
lcme_flags: init
lcme_extent.e_start: 134217728
lcme_extent.e_end: 2147483648
lmm_stripe_count: 2
lmm_stripe_size: 4194304
lmm_pattern: raid0
lmm_layout_gen: 0
lmm_stripe_offset: 2
lmm_objects:
- 0: { l_ost_idx: 2, l_fid: [0x100020000:0x6e:0x0] }
- 1: { l_ost_idx: 1, l_fid: [0x100010000:0x6f:0x0] }
lcme_id: 5
lcme_mirror_id: 0
lcme_flags: init
lcme_extent.e_start: 2147483648
lcme_extent.e_end: 6979321856
lmm_stripe_count: 3
lmm_stripe_size: 4194304
lmm_pattern: raid0
lmm_layout_gen: 0
lmm_stripe_offset: 2
lmm_objects:
- 0: { l_ost_idx: 2, l_fid: [0x100020000:0x6f:0x0] }
- 1: { l_ost_idx: 1, l_fid: [0x100010000:0x70:0x0] }
- 2: { l_ost_idx: 0, l_fid: [0x100000000:0x6f:0x0] }
lcme_id: 6
lcme_mirror_id: 0
lcme_flags: extension
lcme_extent.e_start: 6979321856
lcme_extent.e_end: EOF
lmm_stripe_count: 0
lmm_extension_size: 268435456
lmm_pattern: raid0
lmm_layout_gen: 0
lmm_stripe_offset: -1
________________________________
From: lustre-discuss <lustre-discuss-bounces at lists.lustre.org> on behalf of BALVERS Martin via lustre-discuss <lustre-discuss at lists.lustre.org>
Sent: Tuesday, July 29, 2025 09:19
To: Vicker, Darby J. (JSC-EG111)[Jacobs Technology, Inc.] <darby.vicker-1 at nasa.gov>; lustre-discuss <lustre-discuss at lists.lustre.org>
Subject: Re: [lustre-discuss] [EXTERNAL] [BULK] No ZFS compression on OST's when using PFL
WARNING - EXTERNAL SENDER - BE CYBERSAFE
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
WARNING - EXTERNAL SENDER - BE CYBERSAFE
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
CAUTION: This email originated from outside of NASA. Please take care when clicking links or opening attachments. Use the "Report Message" button to report suspicious messages to the NASA SOC.
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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