X server not running after migrating from ESXi to Proxmox on CentOS 7 VMs

[jameswang]

Hello,

We were a VMWare shop for over 15 years. Recently I migrated most of our VMs from ESXi into Proxmox 7.2 (new to proxmox). Initially we had server random crash issue. It was fixed by identifying a couple of failed ram modules. The two clustered Proxmox servers have been up and stable for over 50 days and we are very happy with their performances.

We still have a few VMs on ESXi. We ran into an issue that prevents us from migrating these servers over.

We have servers run CentOS 7.9 and provide ssh access to our users. When a user ssh into the server using Windows SSH Tectia with X11 tunneling enabled and Xming running in background, they can run xterm, xmail, emacs, ddd, etc.

'netstat -na' would show:

tcp 0 0 127.0.0.1:6010 0.0.0.0:* LISTEN

and 'echo $DISPLAY' shows 'localhost:10.0'.

After migrating the servers to Proxmox, when a user ssh into the server using the same ways, they get "Error: Can't open display:". 'netstat -na' command shows no tcp port opening/listening on 6000+offset. 'echo $DISPLAY' shows: DISPLAY: Undefined variable.

VMs that run Rocky Linux 8 or Ubuntu work on X11 tunneling after migration. None of the CentOS 7 VMs work. We have users depend on X11 tunneling to run their X applications. I had to move some of the CentOS 7 VMs back to EXSi until this issue is resolved.

Any help is greatly appreciated.

Thank you.

James Wang

 

[bbgeek17]

Its very unlikely that your X forwarding issues have anything to do with PVE as a hypervisor.

Have you tried following one of many guides to see if you can bring up X sessions manually? Have you ruled out that post-migration changes could have affected the configuration? i.e. new IP, new NIC designation, different user, profile, etc.

https://aws.amazon.com/blogs/comput...port-gui-based-installations-from-amazon-ec2/

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Blockbridge : Ultra low latency all-NVME shared storage for Proxmox - https://www.blockbridge.com/proxmox

 

[jameswang]

Its very unlikely that your X forwarding issues have anything to do with PVE as a hypervisor.

Have you tried following one of many guides to see if you can bring up X sessions manually? Have you ruled out that post-migration changes could have affected the configuration? i.e. new IP, new NIC designation, different user, profile, etc.

https://aws.amazon.com/blogs/comput...port-gui-based-installations-from-amazon-ec2/

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Blockbridge : Ultra low latency all-NVME shared storage for Proxmox - https://www.blockbridge.com/proxmox

Thank you bbgeek. I will go through the link and give it a try.

I created a brand new VM in PVE and installed CentOS 7.9 on it. The X11 forwarding works. So it has to do with the new virtual hardware like you mentioned new NIC designation , change in drivers, or something similar.

I did try all the display options under "Hardware" and none helped. Server IPs are the same but they did have new Mac addresses. Users are centrally managed and profiles are NFS mounted.

 

[bbgeek17]

The hardware for display does not matter at all. It could be a completely headless server for X over ssh to work. The issue is in your OS configuration somewhere

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Blockbridge : Ultra low latency all-NVME shared storage for Proxmox - https://www.blockbridge.com/proxmox