@olivierlambert Thanks! Just read this and after experimenting with dynamic memory I see what you mean!

@nikade thanks for the ideas of where to look!

In my case we're testing and just have a 1Gb link between these hosts, which is what I was putting it down to.

This particular VM is a freshly migrated PV from Debian Xen with:

Memory limits (min/max)
Static: 16 MiB/16 GiB
Dynamic: 8 GiB/16 GiB

Could that Dynamic setting be the problem because as I recall it reduces the VM to 8 on migrate, so when doing the migrate perhaps 8 isn't enough for the VM?

I will try changing it to 16/16 and see if that has any noticeable impact. Thanks!

We're seeing this issue when trying to migrate a Debian VM with 16GB of RAM.

It is a worker node in a Kubernetes cluster so it is likely that the RAM changes a fair bit. It is not uncommon for the migration to fail due to the freeze hitting a 30 second time limit.

A Windows 10 Pro VM with 16GB of RAM migrates fine, because not much is changing in the RAM I expect.

Following along for recommendations! Our hosts sound very similar to @arc1 except our network speed is slower, which is one thing we are working on.

I have been migrating VMs from Xen on Debian 11/12 using the python2 script this past week and it worked best if I had ensured the VMs were booting on Debian using pygrub as the bootloader rather than the specified kernel from the Dom0.

Then all I had to do after running the script was go into Xen Orchestra and change the "PV args" for the VM under "Advanced" to "root=/dev/xvda ro" (instead of "root=/dev/xvda2 ro" from the imported config), edit the "Network" config to match the MAC addresses used by the VM before, and mount the tools disk.

The VM will then boot and I can edit the /etc/fstab file to use xvda and xvdb for the boot disk and swap respectively (instead of xvda2 and xvda1 that Debian had been using).

I edited my VM's /etc/network/interfaces (because we have standardised on having the internal network as the first ethernet port rather than the second), then mounted the tools and ran 'sudo /mnt/Linux/install.sh' before rebooting. It is a pretty quick process once you've done a dozen or so!!

I tried updating the script to use python3 but as I am not a python developer I decided it was safer to build python2.7 from sources to run on Debian 12, since unfortunately python 2 is no longer available from packages on Debian 12.

Thanks for sharing your experience here, which I thought I would just add to as it may help others migrating to xcp-ng over coming months/years. All I can say is, "Do it!". The sooner the better!

Once I have all the VM migrated in PV mode, I will then work on moving to HVM.

I also worked on trying to update the script to python3 last week and hadn't realised you had this work here so was starting from scratch.

I am not a python developer so when I got to errors in the section that is actually streaming the files I decided to stop and just finish 'making' python2.7 on the servers that I need to get the VMs off and that has worked for me.

It doesn't seem like it should be a huge amount of work left to upgrade the script to python3 but probably not something I have the skills or time for right now.

Thanks for sharing your efforts here. What have you ended up doing @josef1909