Do you have pointers to articles supporting this statement? A small size ARC should not rise problems, except performance wise...?
The practical lower limit is only reached when the ZFS internal data structures do not fit into it anymore. The concept: https://openzfs.github.io/openzfs-docs/Performance and Tuning/Workload Tuning.html#adaptive-replacement-cache
----
Edit: an obviously extreme example - on the *BSD side, not OpenZFS: https://wiki.freebsd.org/ZFSTuningGuide#ARC --> "vfs.zfs.arc_max="40M""
Problem encountered: RAM saturation and ZFS ARC limit exceeded, resulting in a system crash.
Test environment:
Laptop with 16 GB of RAM.
ZFS installation with the ARC limited to 2 GB (zfs_arc_max = 2 GB).
Operating system and running applications consuming approximately 4 GB of RAM.
3 virtual machines running, using approximately 8 GB of RAM in total.
Procedure triggering the incident:
Running an rsync script on the host machine to perform a backup of approximately 20 GB, while the 3 VMs were already running.
Observed result:
Despite the 2 GB limit, the ARC cache exceeded this value during the backup. The available RAM was completely consumed, the system froze (no response), and a forced reboot was required. Upon reboot, corruption was observed.
I am not the only one to have had a similar problem, it seems to me that there is an open bug that resembles this scenario.