After I talked about resources management within vSphere Integrated Containers some questions arose immediately:
What happens if I try to create containers above the limits?
That’s what I’m about to demonstrate today, let’s take this journey together, shall we?
By default, the VCH endpoint VM has 1vCPU and 2GB of memory and that's what we'll work on with.
With that said, the first VCH I’ll create has a low CPU limit (only 100MHz);
Apparently, the VCH creation went normally, but during the endpoint VM communication validation step some errors were reported, which what looks like is a timeout issue;
If we take a look at vSphere, the endpoint VM is taking a long time to boot-up, just showing a banner on it’s console...
… eventually, it boot’s up but with some errors on the console, you might try, but even a simple “ping” does not work.
Looking further, we can see on the performance chart that the VMs is Entitled to only 100MHz, the same amount which was specified by the VCH creation.
So during the boot process, the endpoint VM Demands more than what it’s entitled to, that’s when we saw a high READY time, meaning that the VMs is ready to run but could not get scheduled on the physical ESXi CPU.
Now the time-out make sense ; )
Let’s try differently this time, let’s create a VCH with a low memory limit (only 100MB);
This time the VCH creation fails with a more descriptive message. "Failed to power on appliance. The available Memory resources in the parent resource pool are insufficient for the operation"
As we can see there’s not enough memory to power one the endpoint VM so it cannot proceed.
Well, it’s clear that at least we need to set the limits higher that the VCH endpoint configuration.
I think it’s enough for one post, next I will cover what happens when the containers consume more than the Limits.
Stay tuned !!
