ZFS ARC size growing?

[Greg_E]

I've been noticing this and wanted to ask to check. I did a long overdue update last night and a reboot, that went fine. But I looked and see my ZFS ARC at 2.1GB, the previous size was over 4GB and it seems to clear out on reboot (which is probably normal). I did not make any adjustments to the cache size, so it's running at whatever default values are set in the Business version, Intel Xeon processor, intel i350 and i219 NICs, 16GB of ECC ram, Supermicro main board and chassis (more specific if needed).

Is it normal for this to grow as time goes on? It's never really gotten big enough to worry about, seems there is something every couple of months that needs a reboot. Mostly just checking to see if this is normal. On my Truenas systems, ZFS ARC will vary a lot depending on what it is doing and may use almost all free RAM, but then it goes back down after a short amount of time where the ARC in OPNsense seems to just grow and stay at that size.

[cookiemonster]

In a very short way:
ARC growing : normal.
ARC resetting on reboot : normal.
ARC not going to lower levels than you expect : With deafauls on freeBSD, OS takes care of utilising as much as possible memory and free it as needed but can be limited with tunables. I do not know if OPN has altered defaults. You can alter them yourself but it takes some knowledge of load types to get something that works for you. Suggest to not do it.
I use tunables in NASes as I have a mixed load, but leave OPN with defaults.

[Greg_E]

Thanks, this was more a sanity check than a real problem.