Can't start VM

TrueNAS General
1

So, I have 94.2 GB Ram, 22.2 used by services, 67.4 ZFS cache, and, 4.5G free according to the dashbiard. I try and start a 8GB VM, and, problem. Error: not enough memory and it asks me to overcommit but says use with caution. Given we have eliminated swap space, and given I don’t know how much RAM the VM will actually use or how quickly…

I presume it’s safe to “overcommit” and hopefully ZFS will then free some. But there is no mention of anything other than use with caution in the message that comes up. I have a whole group of VMs I activate here or there, not at startup. Now that I am on Dragonfish.

So, I ask, what is the correct way to handle this? If it’s truly ok to start, not sure what Scale actually does behind the scenes, then can the message be improved as currently saying use with caution is not very comforting. Clearly I actually have 71.9G memory free if zfs cache went to 0.

If I start the VM via virsh (after dumping the xml), I notice that a lot of memory is freed before it starts the VM just fine. It reduced the ZFS arc to less than half memory.

2

You aren’t low on ZFS cache so just start it and Report a Bug if something happens. Linux is seeing all memory usage as the same.

3

I filed a bug for this

NAS-129490: VM won’t start without a warning because of Dragonfish ARC changes

Apparently its fixed in 24.10 (Electric Eel)

In the meantime, if you have enough ARC cache to dump, then ignore the warning and check the checkbox.

The fix is basically to include “droppable memory” in the free memory.

4

Sure, but, I am suggesting here and hoping for a IX reply as it’s already a bug in my view before I hit the button. And I am not fond of no swap space at all, I can’t take a OOM right now. So, it will have to wait to just hit it.

5

Exactly my point, so thanks for already reporting it! Still waiting on docker to drop in Eel so I can start testing.