Dug a little deeper. For a VM where the disks are not shown the following XO API call fails: /rest/v0/vms/a519e879-3971-9210-51b6-7df14336e7b7/vdis { "error": "no such VDI ac37700d-3157-4df7-b8e8-e1799a994591", "data": { "id": "ac37700d-3157-4df7-b8e8-e1799a994591", "type": [ "VDI" ] } } Also the VDI cannot be retrieved over the XO API: /rest/v0/vms/a519e879-3971-9210-51b6-7df14336e7b7 ... "$VBDs": [ "4ea8a3cd-0d1b-dc60-4d9c-fd70e060f06c", "9f4ca686-9fc2-35a9-c3e9-c871c9f68aba" ], ... /rest/v0/vbds/9f4ca686-9fc2-35a9-c3e9-c871c9f68aba { "type": "VBD", "attached": false, "bootable": false, "device": "xvda", "is_cd_drive": false, "position": "0", "read_only": false, "VDI": "ac37700d-3157-4df7-b8e8-e1799a994591", "VM": "a519e879-3971-9210-51b6-7df14336e7b7", "id": "9f4ca686-9fc2-35a9-c3e9-c871c9f68aba", "uuid": "9f4ca686-9fc2-35a9-c3e9-c871c9f68aba", "$pool": "93d361b7-f549-53b7-a3aa-c9695bf0abe4", "$poolId": "93d361b7-f549-53b7-a3aa-c9695bf0abe4", "_xapiRef": "OpaqueRef:1d424d94-f540-2eb4-9e52-2a9b21ec0a19" } /rest/v0/vdis/ac37700d-3157-4df7-b8e8-e1799a994591 { "error": "no such VDI ac37700d-3157-4df7-b8e8-e1799a994591", "data": { "id": "ac37700d-3157-4df7-b8e8-e1799a994591", "type": "VDI" } } However the VDI can be listed using the xe cli: $ xe vm-list uuid=a519e879-3971-9210-51b6-7df14336e7b7 uuid ( RO) : a519e879-3971-9210-51b6-7df14336e7b7 name-label ( RW): XXX power-state ( RO): halted $ xe vbd-list vm-uuid=a519e879-3971-9210-51b6-7df14336e7b7 uuid ( RO) : 4ea8a3cd-0d1b-dc60-4d9c-fd70e060f06c vm-uuid ( RO): a519e879-3971-9210-51b6-7df14336e7b7 vm-name-label ( RO): XXX vdi-uuid ( RO): <not in database> empty ( RO): true device ( RO): xvdd uuid ( RO) : 9f4ca686-9fc2-35a9-c3e9-c871c9f68aba vm-uuid ( RO): a519e879-3971-9210-51b6-7df14336e7b7 vm-name-label ( RO): XXX vdi-uuid ( RO): ac37700d-3157-4df7-b8e8-e1799a994591 empty ( RO): false device ( RO): xvda $ xe vdi-list uuid=ac37700d-3157-4df7-b8e8-e1799a994591 uuid ( RO) : ac37700d-3157-4df7-b8e8-e1799a994591 name-label ( RW): XXX Disk 0 name-description ( RW): Created by XO sr-uuid ( RO): 977b7e63-bb84-57b2-3e0d-206afea553bf virtual-size ( RO): 34359738368 sharable ( RO): false read-only ( RO): false Seems almost like something changed in the XCP-ng API which XO cannot consume.

okay weird. Let's see if there's other reports then

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?

@olivierlambert said in Backup-NG Error "invalid header checksum" after VM-Disk-Resize and reaching retention Limit.: So the issue appeared just when the oldest extended delta had to be merged in the full I suppose. This is exact, but we need to have a proper process to reproduce it. This might be related to: increasing the size of the disk above a certain threshold increasing the content of the disk above a certain threshold