memory usage for large servers

[ggiinnoo]

Let me start of by knowing zfs/truenas will only use half of the memory for it's cache purpose so with 32gb of ram, it will use 16gb wich for a small server is smart.

The dilemma i'm facing is with servers with a huge amount of memory, like mine.
I got 378gb of memory and zfs/truenas will only use 189 of it for cache wich means 189gb of memory is wasted.
I know you need extra memory for other services like plex, vm's and other containers but that could easily be done with 64gb wich leaves about 128gb on the table for caching.

Would it be an idea to set the 50% mark higher with the more memory you have starting with 256gb to use 75% of it.

It is possible to set it manualy with `zfs_arc_max` but a more automatic way might be better/

 

[sretalla]

This has been covered in many other threads, largely ending with the conclusion that Linux memory management sucks and there's no real way around it.

If you want all your memory to be in scope for ZFS, use TrueNAS CORE.

Playing with that setting is certainly possible, but deemed risky as memory shortage can cause ZFS instability.

EDIT: I see you've posted this in a TrueNAS CORE forum, but this problem that you describe is specific to Linux (TrueNAS SCALE)... if you're not using all your memory, you may not yet have done enough to cause it to be used... have a look at arc_summary and watch it as you use the server.

 

[ggiinnoo]

You are right yes. And i am thinking of switching over to core for this reason. I got the memory, i want to use it dammit
The only reason i got scale was for plex and vm's But i'm going to configure a new server for that.

 

[winnielinnie]

The only reason i got scale was for plex and vm's

You must fight the temptation! Stay strong, my friend. Stay strong.

 

[NugentS]

Its possible that Cobia might have a better take on this. I doubt as good as Core - but hopefully better than 50%

 

[jgreco]

You must fight the temptation! Stay strong, my friend. Stay strong.

You can do VM's on CORE and Plex in a VM, so there's not a real reason to mess with SCALE for this minor wishlist.

 

[ggiinnoo]

I had core running a couple years on the 'Main nas' in my bio. But it had issues with the 8086k. Some weird reboots and such. There was a specific way of starting the nas i then switched to scale on a 'new' server and got a nvidia P4 for transcoding.

Now i wish i stayed on core.

BUT! you are correct, you can run VM's and jail stuff. But i like to experiment. Wich isn't always a smart thing to do but o well.