Hello,
I have a 13.2-RELEASE-p3 system with a large storage attached:
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NAME SIZE ALLOC FREE CKPOINT EXPANDSZ FRAG CAP DEDUP
HEALTH ALTROOT
tank 135T 122T 12.8T - - 66% 90% 1.27x
ONLINE -
zroot 31.5G 27.8G 3.74G - - 70% 88% 1.00x
ONLINE -
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In order to process some newly incoming files I'd like to use the zfs
diff functionality to get the list of the files created or modified. So
I wrote a simple script (/root/periodic/zfsdiff) diffing two dataset
snapshots between today and yesterday. Most of these launches do merely
work. But not all of them. Some (like 15%) just are waiting for
something infinitely, while seemingly doing nothing:
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39935 - I 18101:52,29 zfs diff tank/data/tank2@2025-01-20
tank/data/tank2@2025-01-21
46118 - Is 0:00,00 /bin/sh /root/periodic/zfsdiff
46126 - I 354:34,75 zfs diff tank/data/tank0@2025-02-03
tank/data/tank0@2025-02-04
49620 - I 2155:14,42 zfs diff tank/data/tank1@2025-02-10
tank/data/tank1@2025-02-11
53243 - Is 0:00,00 /bin/sh /root/periodic/zfsdiff
53255 - I 3607:34,83 zfs diff tank/data/tank0@2025-02-09
tank/data/tank0@2025-02-10
56849 - Is 0:00,00 /bin/sh /root/periodic/zfsdiff
59725 - I 3630:23,01 zfs diff tank/data/tank2@2025-01-27
tank/data/tank2@2025-01-28
65460 - I 1425:25,55 zfs diff tank/data/tank1@2025-02-03
tank/data/tank1@2025-02-04
82371 - I 111:25,63 zfs diff tank/data/tank3@2025-02-11
tank/data/tank3@2025-02-12
98172 - Is 0:00,00 /bin/sh /root/periodic/zfsdiff
98223 - I 4792:11,99 zfs diff tank/data/tank3@2025-02-04
tank/data/tank3@2025-02-05
40589 2 IN 18108:48,07 zfs diff tank/data/tank2@2025-01-20
tank/data/tank2@2025-01-21
28649 6 I+ 471:24,81 zfs diff tank/data/tank1@2025-02-03
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Surprisingly, this has little to no correlation to the size of the
snapshot, for instance I have the relatively small snapshot diff that
fails to process (notice the idle process above):
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tank/data/tank1@2025-02-03 31.6M - 16.0T -
tank/data/tank1@2025-02-04 32.5M - 16.0T -
===Cut===
Also, some of these leave no output, without any traces of the script
killed or crashed which is very suspicious as well. You could say that
this probably means there were no changes, but the snapshot size thinks
there were some.
Is there any trick there ? Does this look like a race condition, do I
have to run these sequentially, like one diff at a time ? Can those
interfere with only their fellow diffs, or also with snapshot creation ?
Thanks.
Eugene.
