Post #3699640
2026-05-12 21:08 UTC
Ok, I probably get a thing here...
I applied a temporary sysctl vfs.zfs.arc_max=200000000 to keep ARC usage a bit lower. This does the trick with smaller data subset. Gonna retry the whole big data set when the last smaller rsync test is done.
ARC is supposed to be giving memory back when needed by someone else. It doesn't seem to work well enough on my computer©
Replies (3)
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@paul@notnull.space 2026-05-12 21:12
@joel@gts.tumfatig.net out of interest, is zfs send | zfs recv not an option? I'd expect that to handle zfs to zfs much more efficiently than rsync.
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@olbohlen@norden.social 2026-05-13 06:08
@joel@gts.tumfatig.net ARC takes time to give memory back, it doesn't work like traditional filesystem caches where the pages can just be reused at any time
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@joel@gts.tumfatig.net 2026-05-13 13:09
Another trick seem to not use --delete-before (or --delete-after) flags on rsync because it seems to build some catalog in memory (or such). Using --delete seem to not behave the same way regarding memory consumption - and keep usage low enough to have the process finish.