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?

• same remote-nfs
• identical delta backup job
• VM on the other identical Host.

All working fine as expected.

So it seems that first Host has some Problems and is not providing any useful data when it comes to exporting the first delta snapshot.

Unfortunately i have to change to customer support right now and have to stop my testings for today.
I will keep going tomorrow.

Thx for your support so far.

fully new (empty) NFS-Export mounted as remote in XOA.

• initial full backup in delta backup job successfull.
• delta job fails with "Error: Expected values to be strictly equal: 430 !== 1536"

i will crosstest now with a VM on the working Host.

its a 12-Disk Synology-NAS with btrfs.
On that NFS-Storage are multiple folders exported as remotes in my XOfs Installations.
As i said. All other Hosts/XOfs Installations work fine on that NFS-Storage.
Only this one specific XCP-ng Host has these Problems. So i think its not XenOrchestra related. It seems to be a problem with XCP-ng on this specific Host, but the identical second Host does not have this Problem.

I will make new tests with the XOA and tell my findings.

Meanwhile i found out why the backup-job is hanging forever on my new XOfs Installation.

When i mounted the NFS-remote, i checked the option "Store backup as multiple data".

I removed the remote-nfs and reconnected it without that option.
Now the full backup is working as expected and the first delta fails with "Error: stream has ended with not enough data (actual: 430, expected: 512)".

So maybe there is a difference in the error handling when this option is active and the exception is not handled correctly.
Just for your Information.

I will come back when i tested with XOA.