Dear @CJ, We have added an article in our documentation that explains why full exports sometimes happen unexpectedly. You can find this article on this page. I hope it clarifies, do not hesitate to tell us your opinion!

Yeah this is relatively normal, it's using 2MiB blocks so there are going to be a lot of requests when you are doing this with large VMs or data. Are these a ton of VMs or a few larger ones? If the later, might be worth moving that data to a NAS of some kinda, TrueNAS or whatever, and have the NAS handle the backup of it so that the VMs remain light and nimble. Of course that only works IF you can do that.

Good news then

You do not enable NBD in your VM, you enable NBD on a XCP-ng network, that's it. There's no drawback to enable it (well, it's a new service exposed but it's OK)

@Gheppy I would have done those operation, if i wouldn't loose connection to xcp-ng. I got only 1 IP address which is dedicated to pfsense, and from there i connect to xcp-ng (LAN side).

Hi, sorry for the long break. i'll continue here for my colleague AlexD2006. We have now also tried with the current version (deeb3) of Xen-Orchestra, the problem remains the same. But we have now noticed other error messages (also with the old version) that appear during a delta backup ("base VDI is not a vhd; cannot compute differences"): May 23 16:40:35 xcp-mono02 xapi: [error||7644621 HTTPS 10.32.1.159->:::80|[XO] Exporting content of VDI test-vm.test 1 R:2e892fda7776|vhd_tool_wrapper] base VDI is not a vhd; cannot compute differences May 23 16:40:37 xcp-mono02 xapi: [error||7644621 :::80||backtrace] [XO] Exporting content of VDI test-vm.test 1 R:2e892fda7776 failed with exception (Failure "base VDI is not a vhd; cannot compute differences") May 23 16:40:37 xcp-mono02 xapi: [error||7644621 :::80||backtrace] Raised (Failure "base VDI is not a vhd; cannot compute differences") May 23 16:40:37 xcp-mono02 xapi: [error||7644621 :::80||backtrace] 1/14 xapi Raised at file stdlib.ml, line 29 May 23 16:40:37 xcp-mono02 xapi: [error||7644621 :::80||backtrace] 2/14 xapi Called from file ocaml/xapi/vhd_tool_wrapper.ml, line 206 May 23 16:40:37 xcp-mono02 xapi: [error||7644621 :::80||backtrace] 3/14 xapi Called from file ocaml/xapi/export_raw_vdi.ml, line 50 May 23 16:40:37 xcp-mono02 xapi: [error||7644621 :::80||backtrace] 4/14 xapi Called from file lib/xapi-stdext-pervasives/pervasiveext.ml, line 24 May 23 16:40:37 xcp-mono02 xapi: [error||7644621 :::80||backtrace] 5/14 xapi Called from file lib/xapi-stdext-pervasives/pervasiveext.ml, line 35 May 23 16:40:37 xcp-mono02 xapi: [error||7644621 :::80||backtrace] 6/14 xapi Called from file lib/xapi-stdext-pervasives/pervasiveext.ml, line 24 May 23 16:40:37 xcp-mono02 xapi: [error||7644621 :::80||backtrace] 7/14 xapi Called from file lib/xapi-stdext-pervasives/pervasiveext.ml, line 35 May 23 16:40:37 xcp-mono02 xapi: [error||7644621 :::80||backtrace] 8/14 xapi Called from file ocaml/xapi/export_raw_vdi.ml, line 90 May 23 16:40:37 xcp-mono02 xapi: [error||7644621 :::80||backtrace] 9/14 xapi Called from file ocaml/xapi/export_raw_vdi.ml, line 116 May 23 16:40:37 xcp-mono02 xapi: [error||7644621 :::80||backtrace] 10/14 xapi Called from file ocaml/xapi/server_helpers.ml, line 101 May 23 16:40:37 xcp-mono02 xapi: [error||7644621 :::80||backtrace] 11/14 xapi Called from file ocaml/xapi/server_helpers.ml, line 122 May 23 16:40:37 xcp-mono02 xapi: [error||7644621 :::80||backtrace] 12/14 xapi Called from file lib/xapi-stdext-pervasives/pervasiveext.ml, line 24 May 23 16:40:37 xcp-mono02 xapi: [error||7644621 :::80||backtrace] 13/14 xapi Called from file string.ml, line 115 May 23 16:40:37 xcp-mono02 xapi: [error||7644621 :::80||backtrace] 14/14 xapi Called from file src/sexp.ml, line 113 May 23 16:40:37 xcp-mono02 xapi: [error||7644621 :::80||backtrace] Can anyone say anything about the cause of the problem or any ideas for further analysis?

It is very simple. Whatever happens to your system, you can re-import your previous metadata on a fresh system and everything will be back on track as it were before the issue.

@Darkbeldin Done. Thanks for the reply. It took a while to make sure I was understanding it, but I think I've got the hang of it now.

@olivierlambert Thank you for following up.

Not yet, it's not top priority until we got our new backup code ready. After that, it might be easier than before