Timestamp lost in Continuous Replication

[kratos]

Hello everyone,

I’m not sure if my information is useful, but I’m experiencing the same problem. I am using continuous replication between two servers with a retention of 4.
Previously, four VM replicas were created, each with a timestamp in the name. With the current version, four VMs are created with identical names.

My environment:
XO: from source commit 598ab
xcp-ng: 8.3.0 with the latest patches

My backup job:
Name of backup job: replicate_to_srv002
Source server: srv003
Target server: srv002
VM name: privat
Retention: 4

Result on the target server:
4 VMs with the name "[XO Backup replicate_to_srv002] privat - replicate_to_srv002", where only the newest one contains a snapshot named: "privat - replicate_to_srv002 - (20260318T083542Z)"

Additionally, full backups are created on every run of the backup job, and no deltas are being used.

If I can help with any additional information, I’d be happy to do so.

Best regards,
Simon

[Pilow]

@kratos @florent shouldn't he have one VM with 4 snapshots ? and delta replicas between each snap ?

[kratos]

@Pilow
actually it looks like this:

edit:

Log of last run:

{
  "data": {
    "mode": "delta",
    "reportWhen": "failure"
  },
  "id": "1773822934377",
  "jobId": "a95ac100-0e20-49c5-9270-c0306ee2852f",
  "jobName": "replicate_to_srv002",
  "message": "backup",
  "scheduleId": "1014584a-228c-4049-8912-51ab1b24925a",
  "start": 1773822934377,
  "status": "success",
  "infos": [
    {
      "data": {
        "vms": [
          "224a73db-9bc6-13d6-cc8e-0bf22dbede73"
        ]
      },
      "message": "vms"
    }
  ],
  "tasks": [
    {
      "data": {
        "type": "VM",
        "id": "224a73db-9bc6-13d6-cc8e-0bf22dbede73",
        "name_label": "privat"
      },
      "id": "1773822936247",
      "message": "backup VM",
      "start": 1773822936247,
      "status": "success",
      "tasks": [
        {
          "id": "1773822937378",
          "message": "snapshot",
          "start": 1773822937378,
          "status": "success",
          "end": 1773822940361,
          "result": "d0ba1483-f5ae-ce72-fb4f-dbd9eafbf272"
        },
        {
          "data": {
            "id": "8205e6c4-4d8f-69d9-6315-9ee89af8e307",
            "isFull": true,
            "name_label": "Local storage",
            "type": "SR"
          },
          "id": "1773822940361:0",
          "message": "export",
          "start": 1773822940361,
          "status": "success",
          "tasks": [
            {
              "id": "1773822942354",
              "message": "transfer",
              "start": 1773822942354,
              "status": "success",
              "tasks": [
                {
                  "id": "1773823497635",
                  "message": "target snapshot",
                  "start": 1773823497635,
                  "status": "success",
                  "end": 1773823500290,
                  "result": "OpaqueRef:53bceb07-a69c-504d-e824-28f5384cb763"
                }
              ],
              "end": 1773823500290,
              "result": {
                "size": 61941481472
              }
            },
            {
              "id": "1773823501512",
              "message": "health check",
              "start": 1773823501512,
              "status": "success",
              "tasks": [
                {
                  "id": "1773823501515",
                  "message": "cloning-vm",
                  "start": 1773823501515,
                  "status": "success",
                  "end": 1773823504720,
                  "result": "OpaqueRef:43e9644f-fc99-963a-4a54-da3b845e823b"
                },
                {
                  "id": "1773823504722",
                  "message": "vmstart",
                  "start": 1773823504722,
                  "status": "success",
                  "end": 1773823545662
                }
              ],
              "end": 1773823549312
            }
          ],
          "end": 1773823549312
        }
      ],
      "end": 1773823549319
    }
  ],
  "end": 1773823549319
}

[florent]

@kratos @pilow is it possible that your replications are in the same pool ?

[kratos]

@florent
Yes, that is absolutely correct. I have a pool with two members without shared storage. Some VMs run on the master, and some on the second pool member. I replicate between the pool members so that, if necessary, I can start the VMs on the other member. This may not be best practice.

[florent]

@kratos you probably heard the sound of my head hitting my desk when I found the cause
the fix is in review, you will be able to use it in a few hours

[kratos]

@florent
I’m a developer myself, so I can totally relate—just when you think everything is working perfectly, someone like me comes along
I’m really glad I could help contribute to finding a solution, and I’ll report back once I’ve tested the new commit. Thanks a lot for your work.

However, this does raise the question for me: is my use case for continuous replication really that unusual?

[florent]

@kratos no, it's not that rare. I even saw in the wild replication on the same storage (wouldn't recommend it , though )

the cross pool replication is a little harder since the objects are each split on their own xen api, so the calls must be routed to the right one
We tested the harder part, not the mono xapi case

[Pilow]

@kratos said:

This may not be best practice.

in a two hosts pool, if your replicated VMs live on the Master, and it's gone, you won't be able to start the replicated VMs

you will first need to transition slave to master

indeed CR is better to another pool

[ph7]

updated to f5468 and it seems to work fine in my home lab lab
I will update my homelab "production" later

I have retention of 2
In XO I only see 1 VM and I think this is intended
I get 2 snaps and I can restore 2 different VMs from them

I think You nailed it

edit: And delta is back