Configuring VMware vSphere ESXi Dump Collector on vCenter 7

After (re)-installing ESXi 7.0.0 and vCenter 7.0.2 in my Intel NUC Gen. 8 Homelab, vCenter presented me a warning for all my three hosts.
No coredump target has been configured. Host core dumps cannot be saved.

No coredump target has been configured. Host core dumps cannot be saved.
No coredump target has been configured. Host core dumps cannot be saved.

At the time of this post, i boot my ESXi-Hosts from USB-Devices, with the internal SATA- and NVMe-Disks forming an All-Flash vSAN-Cluster with no additional network or local storage to “outsource” the core dumps.

Disable / Suppress the warning

A simple and easy to apply approach is to just disable or suppress the warning. Which in a homelab or test enviroment is a choice. I won’t use that setting in a production enviroment.
Just set in the “Advanced System Settings” for “UserVars.SuppressCoredumpWarning” the “Value” from 0 to 1. Another way is from the CLI with the esxcli command:
esxcli system settings advanced set -o /UserVars/SuppressCoredumpWarning -i 1
With the list command you can verify the setting:
esxcli system settings advanced list -o /UserVars/SuppressCoredumpWarning

Configure the USB-Device to store the core dumps

You can also choose to save the core dump to your USB-Boot-Device. In this case you need to configure the kernel option “allowCoreDumpOnUsb=TRUE/FALSE (default FALSE)” to “TRUE” https://kb.vmware.com/s/article/77009. Another way is to set that option through the “Advanced System Settings” for “VMkernel.Boot.allowCoreDumpOnUsb” from “false” to “true”.
The CLI way is:
esxcli system settings kernel set -s allowCoreDumpOnUsb -v TRUE
To show the setting use:
esxcli system settings kernel list | { head -2; grep allowCore;}

Don’t forget to reboot your host.

esxcli system settings kernel set -s allowCoreDumpOnUsb -v TRUE
esxcli system settings kernel set -s allowCoreDumpOnUsb -v TRUE

Configuring the VMware vSphere ESXi Dump Collector on vCenter 7

Another option is to use the vCenter as a core dump target. First you need to enable the VMware vSphere ESXi Dump Collector service on the VAMI-Interface https://vCenterIP_or_FQDN:5480 of the vCenter. Go to VAMI – Services – VMware vSphere ESXi Dump Collector, start the service and set the startup type to “Automatic”. To start the service from the CLI, ssh to your vCenter and start the bash shell.
Use this command to start the service:
service-control --start netdumper
or
vmon-cli --start netdumper
To set the startup type to “Automatic”:
vmon-cli --update netdumper --starttype AUTOMATIC

vmon-cli --update netdumper --starttype AUTOMATIC
vmon-cli –start netdumper // vmon-cli –update netdumper –starttype AUTOMATIC

Configure the ESXi-Hosts to use the vCenter as the core dump target

For configuring the ESXi-Hosts, connect through ssh to your host and use the below esxcli commands to set the parameters.
Set the parameters (–server-port is optional, default is 6500 and –server-ipv4 is deprecated):
esxcli system coredump network set --interface-name=vmk0 --server-ip=172.28.100.10 --server-port=6500
To enable the network service:
esxcli system coredump network set --enable=true
And finally the the configuration:
esxcli system coredump network get
and
esxcli system coredump network check

esxcli system coredump network

Core dump file location

To check the core dump file location on the vCenter Server Appliance, ssh to your vCenter, start the bash shell and look for the netdumper.log file under /var/log/vmware/netdumper/ (i used tail -f, but feel free to use whatever you like to show the output). There you can check the configured size limits and the store location on the filesystem (/var/core/netdumps).
tail -f /var/log/vmware/netdumper/netdumper.log

tail -f /var/log/vmware/netdumper/netdumper.log