325GB of free RAM but "insufficient memory" for new VMs

[Darren]

root@roy-relativity-host1:~# free -h
              total        used        free      shared  buff/cache   available
Mem:           503G        175G         11G         53M        316G        325G
Swap:          7.4G        268M        7.1G

I have 325GB of RAM available but I cannot start any new VMs. I have the balloon driver active and installed on the existing VMs.

Can someone help me to spin up new VMs in this otherwise wasted space?

 

[WhiteStarEOF]

Sure. Let's start with getting the output of a VM that you're trying to start. If you could, just post the output of the command below, and that should give us a good starting point for more questions.

qm start <vmid>

 

[joshin]

Try: "echo 1 > /proc/sys/vm/drop_caches" to do a relatively safe and quick cache flush. You'll be able to start the VM after that.

Proxmox is a touch dumb about not starting a VM when OS memory caches are full, but there's plenty of memory.

 

[Darren]

While I could not spin up new VMs last week, it works this week. I am not sure if an update came down to fix it but I did nothing. RAM usage is steady at 200GB of 512GB. I don't get it.

 

[janos]

Hi,

do you have LXC vm on the same node? I experiance similar when i want to start a KVM vm on a node where there is LXC vms.

 

[LnxBil]

What about memory fragmentation? Have you checked buddyinfo?