@lawrencesystems
Thanks a lot for all the information and recommendations!

@lawrencesystems
And what is this option "Use differential restore" for? Do you have experience with it?

@lawrencesystems
Yes I understand that a normal restore will create a new VM. But there are situations where I just need to overwrite the backed up VM itself. So this is only possible with a snapshot and only the new VM is always restored from the backup?

Hi,
how exactly should I proceed if I want to restore a VM from backup but not as a new VM, but restore/replace the original one to keep the GUID etc.
Thanks in advance.

The update went fine and everything is working fine.

@gduperrey said in XCP-ng 8.3 updates announcements and testing:

xapi: Re-enabled nested virtualization in 8.3, with the same limitations as in 8.2.

Since I keep bothering with nested virtualization here on the forum, I of course immediately tried the support in 8.3

Setup:

• HW XCP-ng 8.3
• • Nested XCP-ng 8.3
• • • Windows Server 2025
• • • Debian 12.9

Windows installation on the nested hypervisor went ok and the system seems to be working fine.
The problem occurred with Debian. ISO 12.9 netistall, UEFI was used. The system boots up and shows the notorious install screen: Graphic install, Install ... Regardless of the type of installation chosen, immediately after starting it, nested hypervisor XCP-ng 8.3 crashes and reboots. By the way, this problem with Debian is also on VMware - if I use nested XCP-ng 8.3 there, the Debian installation crashes it just the same.

It looks like this issue occurs only when saving the backup to non-block storage. When saving to block storage ("Store backup as multiple data blocks instead of a whole VHD file: ON"), it does not, at least in my environment.

It's really confusing. I'm using the current version of XO and I see this in the log:

The value in the file mentioned is the expected value and the backup file itself is the appropriate size:

Xen Orchestra, commit 494ea

As if XO calculates the value before the backup is complete and the file has time to grow a bit?

@florent Clear now, thanks!

Hello @florent may I remind you to make this question clear, when and under what circumstances is compression used and when is it not? Thanks a lot.

@tjkreidl We don't need performance, but we do need to test how XCP-ng pools, networking, migration, live migration, backup, import from VMware and so on work. It's just a playground where we can have relatively many XCP-ng hosts, but it's not about performance, it's about efficiency and low requirements, because it's just a playground where we learn, validate how things work, and prepare the process for the final migration from VMware to XCP-ng. We originally had two R630s ready for this, then 4, but that would have been unnecessary, given the power consumption, to have physical hypervisors, so in the end we decided to virtualize it all. Well, on ESXi it's because XCP-ng works seamlessly there in nested virtualization.

@tjkreidl In the end, everything turned out completely different. In order to make the lab as efficient as possible, we decided to virtualise it. That is, to run XCP-ng hosts as guests on a dedicated hypervisor. This allows us to efficiently turn virtualized hosts on and off, change their CPU counts, etc.

The only problem is that the current version of XCP-ng, or the version of Xen used, does not yet support nested virtualization, so the entire XCP-ng virtual lab "sits" on an ESXi hypervisor.

@manilx Thanks, how simple! I confused myself by thinking of "Block" as a noun, not a verb imperative, being influenced by the NBD term

Hi, what exactly is the purpose of the "Block migration" setting on the Advanced tab of the VM configuration?

I tried to look it up in the documentation at https://docs.xen-orchestra.com, but I had no luck finding it there. Thank you in advance for the explanation.

Hi, I was wondering if it is possible to configure auto-start order of the virtual machines and set related delays. Something similar to this configuration available within an ESXi server:

Regarding my tests and other post on this forum I got the impression that in a single-host environment (lab/test/home env.) it is not possible, that "Start delay (seconds)" option available on the VM´s Advanced tab has no effect in such case (It seems that the VM is started immediately after the host boots up, even if a delay is configured.).

Did I miss something? Thanks a lot in advance for the explaining how this works with XCP-ng and Xen Orchestra.

@tjkreidl Hello, I have two identical Dell R630 servers (BIOS 2.19.0) each with a pair of Intel E5-2680 v4 CPUs in my lab where I am testing deployment scenarios. In the lab, performance is not important, but instead I want to minimize power consumption. Ideally to be able to switch performance "profiles" without having to reboot the servers and toggling settings in the BIOS. Thanks for the link to the article, useful tips and advice there!

Hi,
are there any configurable options for a basic power management policy similar to ESXi?

Restarting the toolstack on the host resolves the CPU count issue in the Stats view.

@florent Can you please provide some summary on backup setup versus compression versus remotes configuration?

@frank-s This confirms my observations and tests that for compression to be active, data blocks must be enabled for remote.

@frank-s Do you have the "data block" option enabled for remote or not?