Home setup memory requirements

[otpi]

According to documentation FreeNAS require minimum 8 GB (ECC) memory. My understanding is that, other than loading the OS, it is basically used for caching data, (L1)ARC and L2ARC.

There is also this rule of thumb thrown around 1 GB RAM for every 1 TB storage. I can understand that an office environment, with lots of users, more caching provide a better user experience. But does it apply for home use? i.e. smb + plex (jail), maybe adding nextcloud.

I currently have 12 GB (3x4GB ECC), and another 3x4 not installed (DIMMS are in trios). So, I have the minimum 8 + another 4, but not according to the rule of thumb.

For my home setup; Does adding more RAM increase performance? When does adding ram increase performance?

(Bonus question: Why is 8 GB the minimum?)

 

[Basil Hendroff]

You may find this link helpful https://www.freenas.org/blog/a-comp...are-design-part-i-purpose-and-best-practices/

 

[Chris Moore]

(Bonus question: Why is 8 GB the minimum?)

Experience has shown that avoiding the occasional system crash required a certain amount of memory. In fact, you can run with less, but the possibility of a problem is increased. FreeNAS can crash if all swap space and all RAM are used. I have had it happen to me.
Most home users are going to be able to manage just fine with what you have. Just keep an eye on the swap use.

 

[otpi]

You may find this link helpful https://www.freenas.org/blog/a-comp...are-design-part-i-purpose-and-best-practices/

That's a very helpful link. From "How much RAM is needed":

FreeNAS requires 8 GB of RAM for the base configuration. If you are using plugins and/or jails, 12 GB is a better starting point. There’s a lot of advice about how RAM hungry ZFS is, how it requires massive amounts of RAM, an oft quoted number is 1GB RAM per TB of storage. The reality is, it’s complicated. ZFS does require a base level of RAM to be stable, and the amount of RAM it needs to be stable does grow with the size of the storage. 8GB of RAM will get you through the 24TB range. Beyond that 16GB is a safer minimum, and once you get past 100TB of storage, 32GB is recommended. However, that’s just to satisfy the stability side of things. ZFS performance lives and dies by its caching. ...

Does that imply usable TB or installed TB?

 

[Chris Moore]

Does that imply usable TB or installed TB?

It is pretty flexible and performance based. I have a system at work that has around 350TB of usable space and 'only' 256GB of memory and it not only works reliably, it is very fast.
I wouldn't worry about it too hard, just keep an eye on the performance metrics the article talks about and also watch out for the system engaging swap space. Once you see how your use of the system (because everyone uses their system differently) impacts the memory use, then you can determine if more memory is called for.

 

[kdragon75]

Lol. I have systems that run ZFS on root with 512MB of RAM. All this "you need over 9000" is due to how FreeNAS is setup and for performance reasons. You could easily run FreeNAS with 4GB if you do some tunning. It will run like garbage but it will run and be stable.