I had the above situation on 2 of the 3 vCenter Appliances in the lab. All 3 are running the latest 5.5 Updates. I found a useful article here, which then link to this great article.

As you can see below, the Coredumps is full. It shows 100%.

To empty it, simply login to the appliance via SSH. I use Bitvise, a great utility, in the example below.

From there, just browse to the directory where we need to delete the files. As shown below, I have a lot of files that I no longer require.

It’s a matter of deleting them. The result is a clean directory 🙂

And the core dump now shows a healthy usage.

Speaking of vCenter, I’d recommend you deploy the vCenter Support Assistant. You should also upgrade your vCenter independently of your ESXi. I have provided some articles on vSphere 6.0, which I hope you find useful:

• How to redirect the vSphere 6.0 Platform Services Controller log
• vSphere 6 Update 1 appliance installation error.
• vSphere 6 enhancements. A tour of the web client.
• Features that are now global (cross vCenter Servers) in vSphere 6