Memory Usage increases really fast

[Theapplefuture]

Hello,
I’m running a fresh install of FreeNAS 11.2 U4 and started copying files from my PC to my NAS. For this evening I only copied 50Gigs and noticed that after that my Memory Usage was at 50Gigs. I assume this is due to the files being copied (ARC or something like that) ?

After I restarted my Server it was back at 2 Gig Memory Usage.

So my question is, what happens when I reach the maximum of my memory usage? Will older files be removed or doesn’t it have to do something with ARC and its something else?

Hope you can educate me..
Greetings

 

[Chris Moore]

There are some useful links to resources in my signature that will help you learn more about the details of how FreeNAS and ZFS work but the short answer is that FreeNAS, really it is the ZFS file system, uses your system memory for ARC (Adaptive Replacement Cache) and will keep your memory filled to around 97% all the time, with all the bits that ZFS thinks might be useful again in the near future, so that it can more quickly answer your requests for data. Not to get too technical about it, but it looks both at the most recently accessed data and the most frequently accessed data to choose what to keep in RAM. When you reboot, it resets all that to zero, so it is better for performance of the cache if you reboot less frequently. My system has not been rebooted in over 97 days.