So /dev/smf is limited to 50% of the ram... and I've been told to do use it for some tasks like plex transcoding as unlike using /tmp the 50% ram limit ensures that your system will not run out of ram and crash. I have 64GB of ram though and use unraid for not much more than a media server, so it seems wasteful to only always have 32GB of ram free at all time. I thought maybe I could increase the % of /dev/smf to 75% by using the startup script things to add the command mount -o remount,size=75% tmpfs /dev/shm" to run at at first array start only.

So will that command work?

1) Like if I go to settings/user in settings and make a new script and put "mount -o remount,size=75% tmpfs /dev/shm" and then set the timing to "at first array start only"

2) Is this a terrible idea? and if so is there another solution?

/dev/shm is limited to 50% of your max memory, it does not take up 50% of your system memory.

Edit: I am assuming you thought that if you don't use it, that 50% of your RAM is going to sit empty.

Otherwise yes you can resize it or create a separate tmpfs and make it whatever size you want using user-scripts

Edited October 30, 2025Oct 30 by MowMdown

As mentioned it's a limit, and transcoding should not use more than a couple of GBs anyway so sure you can increase it but it probably won't change anything since even that much isn't needed anyway.

Edited October 30, 2025Oct 30 by Kilrah

I think I got this working...

nano /boot/config/go

mount -o remout,size=#G /dev/shm

seems to work fine. replace the # with the size you want for "max utilisation".