Feb 7, 2019
Pardon me, as I am sure this is common knowledge for many PVE users. For me, it took many frustrating hours to find the fix, so I will document it here as I have not seen this particular problem/solution laid out explicitly elsewhere. This video from the PVE team documents the fix but does not mention the symptoms of a missing balloon driver/service.

SYMPTOM: Windows Server 2012 and 2016 VMs (and maybe others, I haven't tested) are very slow to start up, with the spinning circle on the Windows splash screen stuttering and getting stuck. The server takes 10 minutes or more to boot, but performs decently after booting.

ENVIRONMENT: Tested on Dell T310, 16GB non-ECC RAM, Intel Xeon X3440, 4x WD Blue 1TB HDD in RAIDZ2. Two Windows Server 2016 Standard VMs installed (with Desktop Experience), each allocated 4 cores/ 6GB RAM. This test setup was designed deliberately to give not-so-great performance, to ensure that the cause was not something like low memory on the host. The symptom manifested immediately after installing two fresh Windows Server 2016 VMs and rebooting.

FIX: Install the Virtio Balloon driver AND the Balloon service in the guest.
  1. Open Device Manager and see if there is an unknown PCI device. If so, right click it and install the driver manually from D:\Balloon\2K16\amd64 (or 2k12, 2k8, etc)
  2. Now copy the entire amd64 folder into C:\Program Files\ (NOT x86) and rename it "Balloon". So, now you have the amd64 folder from the disc copied as C:\Program Files\Balloon
  3. Open an Administrative Command Prompt and cd to C:\Program Files\Balloon
  4. Run this command:
    BLNSVR.exe -i
The balloon service is now installed. This helps Windows VMs with memory management and for me, completely eliminated the slow boot with choppy spinning circle. Hope this helps someone out there!

The video where the PVE team shows how to install the Balloon driver and service is on their YouTube Channel as "Install Wndows 2016 on Proxmox VE"; I cannot post links as I am new to the forum.


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