Copying/creating new files and running 'du' immediately after lead to unexpected output, reporting (smaller) size(s). This happen when using ZFS and apparently doesn't happen when using UFS. Step to reproduce the problem: create a script that: - copy an enough large number of files/size (in a empty directory) - run "du -s directory/*" A preliminry examination on FreeBSD forum is here: https://forums.freebsd.org/threads/56763/ test script: mkdir test cp /boot/kernel/kernel test/kernel1 cp /boot/kernel/kernel test/kernel2 cp /boot/kernel/kernel test/kernel3 cp /boot/kernel/kernel test/kernel4 cp /boot/kernel/kernel test/kernel5 cp /boot/kernel/kernel test/kernel6 cp /boot/kernel/kernel test/kernel7 cp /boot/kernel/kernel test/kernel8 ls -l test du -s test/* unexpected result: total 64748 -r-xr-xr-x 1 root wheel 21551736 Jun 28 21:06 kernel1 -r-xr-xr-x 1 root wheel 21551736 Jun 28 21:06 kernel2 -r-xr-xr-x 1 root wheel 21551736 Jun 28 21:06 kernel3 -r-xr-xr-x 1 root wheel 21551736 Jun 28 21:06 kernel4 -r-xr-xr-x 1 root wheel 21551736 Jun 28 21:06 kernel5 -r-xr-xr-x 1 root wheel 21551736 Jun 28 21:06 kernel6 -r-xr-xr-x 1 root wheel 21551736 Jun 28 21:06 kernel7 -r-xr-xr-x 1 root wheel 21551736 Jun 28 21:06 kernel8 21153 test/kernel1 21153 test/kernel2 21153 test/kernel3 1289 test/kernel4 <-- 1 test/kernel5 <-- 1 test/kernel6 <-- 1 test/kernel7 <-- 1 test/kernel8 <-- note that running 'du' a few seconds later will give the correct result/sizes.
Can confirm this exact issue on 11.1-RELEASE. ZFS filesystem (not UFS) does not show the correct disk usage of a file until after (presumably, per [1]) the transaction group commits. My timings agree with the 6 second sync interval. I do not agree that this is a feature. Causes bup [2]'s t/test-sparse-files.sh testcase to fail as it checks disk usage immediately after (test-) restoring a backup. Therefore it appears the failure is benign. [1] https://forums.freebsd.org/threads/du-behavior.56763/#post-323135 [2] https://github.com/bup/bup
I can confirm this behavior on ubuntu 20.04.