Continuous Replication jobs creates full backups every time since 2025-09-06 (xo from source)

olivierlambert

Feedback for you @florent

JB

@peo Yes, same problem!

Andrew

@olivierlambert @florent Looks like 1471ab0c7c79fa6dca9a1598e7be2a141753ba91 (in current master) has fixed the issue.

But, during testing I found a new related issue (no error messages). Running current XO master b16d5...

During the normal CR delta backup job, two VMs shows the warning message: Backup fell back to a full but it did a delta (not full) backup.

I caused this by running a different CR backup job (for testing) that used the two same VMs but to a different SR. The new test job did a full backup and delta backup correctly. Since there is only one CBT snapshot the normal backup job did recognize that the snapshot was not for the original normal backup job and should have done a full (and started a new CBT snapshot), but it only did a short delta.

As the VMs were off, I guess it could correctly use the other CBT snapshot as no blocks had changed... Just odd that CR backup said it was going to do a full and then did a delta.

JB

@Andrew

florent

@JB this means that it should have done a delta ( as per the full backup interval ) , but had to fall back to a full for at least one disk
this can happens after a failed transfer, a new disk added and some edge case. This issue was not really visible before the latest release, even if the impacts can be important , saturating network and storage.

We are investigating this ( especially @Bastien-Nollet ) , and expect to have a fix and/or an explanation fast

Are you using "purge snapshot data" option ? Are there anything on the journalctl logs ?

JB

@florent Thanks, Florent! No, No!

florent

@JB Doyou have anything related in journalctl ? like can't connect through NBD, fall back to stream export or can't compute delta ${vdiRef} from ${baseRef}, fallBack to a full or anything starting by 'xo:xapi:xapi-disks'

Andrew

@florent

Sep 15 10:00:01 xo1 xo-server[5582]: 2025-09-15T14:00:01.026Z xo:backups:worker INFO starting backup
Sep 15 10:00:32 xo1 xo-server[5582]: 2025-09-15T14:00:32.794Z xo:xapi:xapi-disks INFO Error in openNbdCBT XapiError: SR_BACKEND_FAILURE_460(, Failed to calculate changed blocks for given VD
Is. [opterr=Source and target VDI are unrelated], )
Sep 15 10:00:32 xo1 xo-server[5582]:     at XapiError.wrap (file:///opt/xo/xo-builds/xen-orchestra-202509150942/packages/xen-api/_XapiError.mjs:16:12)
Sep 15 10:00:32 xo1 xo-server[5582]:     at default (file:///opt/xo/xo-builds/xen-orchestra-202509150942/packages/xen-api/_getTaskResult.mjs:13:29)
Sep 15 10:00:32 xo1 xo-server[5582]:     at Xapi._addRecordToCache (file:///opt/xo/xo-builds/xen-orchestra-202509150942/packages/xen-api/index.mjs:1073:24)
Sep 15 10:00:32 xo1 xo-server[5582]:     at file:///opt/xo/xo-builds/xen-orchestra-202509150942/packages/xen-api/index.mjs:1107:14
Sep 15 10:00:32 xo1 xo-server[5582]:     at Array.forEach (<anonymous>)
Sep 15 10:00:32 xo1 xo-server[5582]:     at Xapi._processEvents (file:///opt/xo/xo-builds/xen-orchestra-202509150942/packages/xen-api/index.mjs:1097:12)
Sep 15 10:00:32 xo1 xo-server[5582]:     at Xapi._watchEvents (file:///opt/xo/xo-builds/xen-orchestra-202509150942/packages/xen-api/index.mjs:1270:14)
Sep 15 10:00:32 xo1 xo-server[5582]:     at process.processTicksAndRejections (node:internal/process/task_queues:105:5) {
Sep 15 10:00:32 xo1 xo-server[5582]:   code: 'SR_BACKEND_FAILURE_460',
Sep 15 10:00:32 xo1 xo-server[5582]:   params: [
Sep 15 10:00:32 xo1 xo-server[5582]:     '',
Sep 15 10:00:32 xo1 xo-server[5582]:     'Failed to calculate changed blocks for given VDIs. [opterr=Source and target VDI are unrelated]',
Sep 15 10:00:32 xo1 xo-server[5582]:     ''
Sep 15 10:00:32 xo1 xo-server[5582]:   ],
Sep 15 10:00:32 xo1 xo-server[5582]:   call: undefined,
Sep 15 10:00:32 xo1 xo-server[5582]:   url: undefined,
Sep 15 10:00:32 xo1 xo-server[5582]:   task: task {
Sep 15 10:00:32 xo1 xo-server[5582]:     uuid: '6265a41c-29c3-f4d9-5f0c-e52db6e0fcc9',
Sep 15 10:00:32 xo1 xo-server[5582]:     name_label: 'Async.VDI.list_changed_blocks',
Sep 15 10:00:32 xo1 xo-server[5582]:     name_description: '',
Sep 15 10:00:32 xo1 xo-server[5582]:     allowed_operations: [],
Sep 15 10:00:32 xo1 xo-server[5582]:     current_operations: {},
Sep 15 10:00:32 xo1 xo-server[5582]:     created: '20250915T14:00:32Z',
Sep 15 10:00:32 xo1 xo-server[5582]:     finished: '20250915T14:00:32Z',
Sep 15 10:00:32 xo1 xo-server[5582]:     status: 'failure',
Sep 15 10:00:32 xo1 xo-server[5582]:     resident_on: 'OpaqueRef:65b7a047-094b-4c7a-a503-2823e92b9fe4',
Sep 15 10:00:32 xo1 xo-server[5582]:     progress: 1,
Sep 15 10:00:32 xo1 xo-server[5582]:     type: '<none/>',
Sep 15 10:00:32 xo1 xo-server[5582]:     result: '',
Sep 15 10:00:32 xo1 xo-server[5582]:     error_info: [
Sep 15 10:00:32 xo1 xo-server[5582]:       'SR_BACKEND_FAILURE_460',
Sep 15 10:00:32 xo1 xo-server[5582]:       '',
Sep 15 10:00:32 xo1 xo-server[5582]:       'Failed to calculate changed blocks for given VDIs. [opterr=Source and target VDI are unrelated]',
Sep 15 10:00:32 xo1 xo-server[5582]:       ''
Sep 15 10:00:32 xo1 xo-server[5582]:     ],
Sep 15 10:00:32 xo1 xo-server[5582]:     other_config: {},
Sep 15 10:00:32 xo1 xo-server[5582]:     subtask_of: 'OpaqueRef:NULL',
Sep 15 10:00:32 xo1 xo-server[5582]:     subtasks: [],
Sep 15 10:00:32 xo1 xo-server[5582]:     backtrace: '(((process xapi)(filename lib/backtrace.ml)(line 210))((process xapi)(filename ocaml/xapi/storage_utils.ml)(line 141))((process xapi)(fi
lename ocaml/xapi/message_forwarding.ml)(line 141))((process xapi)(filename ocaml/libs/xapi-stdext/lib/xapi-stdext-pervasives/pervasiveext.ml)(line 24))((process xapi)(filename ocaml/libs/x
api-stdext/lib/xapi-stdext-pervasives/pervasiveext.ml)(line 39))((process xapi)(filename ocaml/xapi/rbac.ml)(line 188))((process xapi)(filename ocaml/xapi/rbac.ml)(line 197))((process xapi)
(filename ocaml/xapi/server_helpers.ml)(line 77)))'
Sep 15 10:00:32 xo1 xo-server[5582]:   }
Sep 15 10:00:32 xo1 xo-server[5582]: }
Sep 15 10:00:35 xo1 xo-server[5582]: 2025-09-15T14:00:35.240Z xo:xapi:vdi WARN invalid HTTP header in response body {
Sep 15 10:00:35 xo1 xo-server[5582]:   body: 'HTTP/1.1 500 Internal Error\r\n' +
Sep 15 10:00:35 xo1 xo-server[5582]:     'content-length: 318\r\n' +
Sep 15 10:00:35 xo1 xo-server[5582]:     'content-type: text/html\r\n' +
Sep 15 10:00:35 xo1 xo-server[5582]:     'connection: close\r\n' +
Sep 15 10:00:35 xo1 xo-server[5582]:     'cache-control: no-cache, no-store\r\n' +
Sep 15 10:00:35 xo1 xo-server[5582]:     '\r\n' +
Sep 15 10:00:35 xo1 xo-server[5582]:     '<html><body><h1>HTTP 500 internal server error</h1>An unexpected error occurred; please wait a while and try again. If the problem persists, please
 contact your support representative.<h1> Additional information </h1>VDI_INCOMPATIBLE_TYPE: [ OpaqueRef:ec54186c-0ab5-0390-d244-64414e9d8887; CBT metadata ]</body></html>'
Sep 15 10:00:35 xo1 xo-server[5582]: }
Sep 15 10:00:35 xo1 xo-server[5582]: 2025-09-15T14:00:35.249Z xo:xapi:xapi-disks WARN can't compute delta OpaqueRef:888ccaa8-07c6-e6f0-3bfb-3e6b5ac4da2a from OpaqueRef:ec54186c-0ab5-0390-d2
44-64414e9d8887, fallBack to a full {
Sep 15 10:00:35 xo1 xo-server[5582]:   error: Error: invalid HTTP header in response body
Sep 15 10:00:35 xo1 xo-server[5582]:       at checkVdiExport (file:///opt/xo/xo-builds/xen-orchestra-202509150942/@xen-orchestra/xapi/vdi.mjs:36:19)
Sep 15 10:00:35 xo1 xo-server[5582]:       at process.processTicksAndRejections (node:internal/process/task_queues:105:5)
Sep 15 10:00:35 xo1 xo-server[5582]:       at async Xapi.exportContent (file:///opt/xo/xo-builds/xen-orchestra-202509150942/@xen-orchestra/xapi/vdi.mjs:244:5)
Sep 15 10:00:35 xo1 xo-server[5582]:       at async #getExportStream (file:///opt/xo/xo-builds/xen-orchestra-202509150942/@xen-orchestra/xapi/disks/XapiVhdStreamSource.mjs:123:20)
Sep 15 10:00:35 xo1 xo-server[5582]:       at async XapiVhdStreamSource.init (file:///opt/xo/xo-builds/xen-orchestra-202509150942/@xen-orchestra/xapi/disks/XapiVhdStreamSource.mjs:135:23)
Sep 15 10:00:35 xo1 xo-server[5582]:       at async #openExportStream (file:///opt/xo/xo-builds/xen-orchestra-202509150942/@xen-orchestra/xapi/disks/Xapi.mjs:128:7)
Sep 15 10:00:35 xo1 xo-server[5582]:       at async #openNbdStream (file:///opt/xo/xo-builds/xen-orchestra-202509150942/@xen-orchestra/xapi/disks/Xapi.mjs:81:22)
Sep 15 10:00:35 xo1 xo-server[5582]:       at async XapiDiskSource.openSource (file:///opt/xo/xo-builds/xen-orchestra-202509150942/@xen-orchestra/xapi/disks/Xapi.mjs:191:18)
Sep 15 10:00:35 xo1 xo-server[5582]:       at async XapiDiskSource.init (file:///opt/xo/xo-builds/xen-orchestra-202509150942/@xen-orchestra/disk-transform/dist/DiskPassthrough.mjs:28:41)
Sep 15 10:00:35 xo1 xo-server[5582]:       at async file:///opt/xo/xo-builds/xen-orchestra-202509150942/@xen-orchestra/backups/_incrementalVm.mjs:67:5
Sep 15 10:00:35 xo1 xo-server[5582]: }

peo

I'm currently testing the "fixed" version. At the time I ran the replications the first time, I expected and accepted it doing new "first" full backups/transfers, but even this small, singe-disk VM (the one for my XO) is still doing full transfers:

This simple operation previously taking 2-5 minutes now takes 44 minutes:

Compared to the previous "normal" backup time:

The same goes for "Admin Ubuntu 24", single but slightly larger disk (50GB) which yesterday took 4 hours (initial "new" "first" backup, so I don't know if it still takes that time)

JB

@florent

I made the backup again and everything went back to normal. Everything is wonderful! Thank you so much!

florent

@Andrew @peo
are you using purge snapshot data ?
In both case, can you try disabling it and disabling CBT on the relevant VMs ?