"Available Memory: 0.10 bytes - ..." I need help with setting vfs.zfs.arc_max ( ?) so my VM's have enough RAM. Thanks

[WallyV]

Available Memory: 0.10 bytes - Caution: Allocating too much memory can slow the system or prevent VMs from running.
TrueNAS-SCALE-21.06-BETA.1
47.0GiB total available
Free: 19.3 GiB
ZFS Cache:22.0 GiB
Services: 5.7 Gib
I have NZBget and Plex installed in Apps and 2 VM's Windows 10 and Debian10. I set 8GB for RAM for each VM. When starting the VMs I see the above message Available Memory: 0/10 bytes. I can start the VMs after ticking a box acknowledging a problem with lack of memory. Both Windows10 and Debian10 VMs boot to UEFI interactive shell. I haven't gotten the Windows10 VM to boot but I have gotten the Debian10 VM to boot but I am stuck in a login loop. Only booting into UEFI shell and login loop are for another day. I wondered if the login loop was caused by lack of memory but there are other possibilities.
I have read many posts about setting a tunable for arc and I am still not getting it.
I understand going to ui/system/advanced then "Add Sysctl"
This was an example I found from last year for a FreeNAS system. I don't know the correct command nor do I understand what value to put for Value.
47GiB total memory
2 VM's with 8 GiB each
Plex & NZBget Apps
2 Pools- 3-10 TB harddrives

• Variable: vfs.zfs.arc_max
• Value: 8589934592
• Type: loader

 

[188pilas]

I used the below instructions to set the arc size.

[solved] How to limit max arc size on TrueNAS SCALE?

I found an option on the misc menu, but that seems to relate to the way FreeBSD used to do it, I think ZFs on Linus is a different method, since Every reboot the system files reset I don't know where I can configure an ARC size limit. A little documentation for the BETA at least would be nice.

www.truenas.com

 

[ornias]

Dont worry about it, the available memory counter is wrong 99% of the time. It's based on a worst case scenario and mistakes the dynamic(!) allocated ARC size as "taken RAM", while the ARC should just shrink once you start enough VM's.

The VM memory takes preference over ZFS memory allocation, there is no need to set max arc size.