The cold ZFS pool is a backup tier only — hot data (MC world, Gitea,
Directus DB, containers) lives on NVMe LVM, not ZFS. So ARC's default of
50% RAM was wasted: nothing it could cache was hot enough to matter, and
the ~16GB cache crowded MC out of RAM, pushing 2.4GB into swap.
This file lives in the repo for reproducibility; it gets dropped into
/etc/modprobe.d/ on the host and applied immediately via
/sys/module/zfs/parameters/zfs_arc_{max,min}.
Effect on glados:
before: used=27/31GB, free=748MB, ARC=15.6GB
after: used=~10GB, free=~14GB, ARC=1.0GB (1-2GB range)
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
Matt
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