SymptomsA Virtuozzo-related task fails with the following error message:
ERRCODE 5000 ERRCODE_MINOR -4 VZALib error, code: -4, msg: Connection to vzagent was closed
The Virtuozzo Node in question operates in compat mode.
CauseMost likely, there are network issues between the POA Management Node and the Service Container of the Virtuozzo Node.
ResolutionThe POA Management Node communicates with the Parallels Virtuozzo Containers server, which is working in compat mode through the Service Container (container with ID #1 on a registered Node) using the SSH protocol on port 22/TCP.
One may perform the following actions to investigate/fix such issues:
1. Check the connection between the Management Node and the Service Container. Execute the following command on the POA Management Node:
# telnet <SCT_IP> 22
Replace "SCT_IP" with the IP address of the Service Container on the Virtuozzo server in question. The command must connect successfully. If it does not, then there are network issues that need to be addressed.
2. Try to restart VZAgent on the Virtuozzo server: log in to the Node as "root" and run the command:
# vzagent_ctl restart
# vzagent_compat_ctl restart
After that, try to resubmit the failed task in POA.
3. If the problem persists, try to log in to the Service Container from the POA Management Node as the user vzagent0:
$ ssh vzagent0@<SCT_IP> -i /usr/local/pem/etc/ssh-keys/vem.key.sec
If login fails, it may indicate that the Node has not been registered in POA yet, or that the corresponding RSA key has been removed from the Service Container. Keys can be checked in the folder ~vzagent0/.ssh/authorized_keys on the Service Container (you can log in to it using vzctl enter 1 from the Virtuozzo Node itself). The file authorized_keys should contain the content of the /usr/local/pem/etc/ssh-keys/vem.key.sec.pub file from the Management Node as single line.
Additional Information1. It is recommended that you have the most up-to-date version of Virtuozzo Tools installed on the Hardware Node. Please install available updates for Virtuozzo Tools using the utility vzup2date.
See the following article for details about vzup2date usage: https://kb.odin.com/1170
2. To determine the IP address of the Service VPS, you may execute the command vzlist 1 on the Virtuozzo Node. You can also do this via the POA CP: Top > Service Director > Virtuozzo Manager > VPS Hardware Nodes > (Node) > IP Address of Service VPS.