qmp command 'backup' failed - backup register image failed: command error: no previous backup found, cannot do incremental backup

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guerbywork

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Mar 23, 2021
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Hi,

On one of our PVE 7.3 host we got a failed PBS 2.3 backup for VMs with message "qmp command 'backup' failed - backup register image failed: command error: no previous backup found, cannot do incremental backup".

After a few tries always the same error message and no backups

I looked at the qemu state via QMP:

Code: 
root@pve:/var/log# socat - unix-connect:/var/run/qemu-server/12001.qmp

{"QMP": {"version": {"qemu": {"micro": 0, "minor": 1, "major": 7}, "package": "pve-qemu-kvm_7.1.0-4"}, "capabilities": []}}
{     "execute": "qmp_capabilities",     "arguments": {}   }
{"return": {}}
{     "execute": "query-block",     "arguments": {}   }

{
  "return": [
    {
      "io-status": "ok",
      "device": "drive-scsi0",
      "locked": false,
      "removable": false,
      "inserted": {
        "iops_rd": 0,
        "detect_zeroes": "unmap",
        "image": {
          "virtual-size": 59055800320,
          "filename": "/dev/zvol/rpool/data/vm-12001-disk-0",
          "format": "raw",
          "actual-size": 0,
          "dirty-flag": false
        },
        "iops_wr": 0,
        "ro": false,
        "node-name": "#block328",
        "backing_file_depth": 0,
        "drv": "raw",
        "iops": 0,
        "bps_wr": 0,
        "write_threshold": 0,
        "dirty-bitmaps": [
          {
            "name": "pbs-incremental-dirty-bitmap",
            "recording": true,
            "persistent": false,
            "busy": false,
            "granularity": 4194304,
            "count": 19423821824
          }
        ],
        "encrypted": false,
        "bps": 0,
        "bps_rd": 0,
        "cache": {
          "no-flush": false,
          "direct": true,
          "writeback": true
        },
        "file": "/dev/zvol/rpool/data/vm-12001-disk-0"
      },
      "qdev": "scsi0",
      "type": "unknown"
    },
    {
      "io-status": "ok",
      "device": "drive-scsi1",
      "locked": false,
      "removable": false,
      "inserted": {
        "iops_rd": 0,
        "detect_zeroes": "unmap",
        "image": {
          "virtual-size": 16106127360,
          "filename": "/dev/zvol/rpool/data/vm-12001-disk-1",
          "format": "raw",
          "actual-size": 0,
          "dirty-flag": false
        },
        "iops_wr": 0,
        "ro": false,
        "node-name": "#block536",
        "backing_file_depth": 0,
        "drv": "raw",
        "iops": 0,
        "bps_wr": 0,
        "write_threshold": 0,
        "dirty-bitmaps": [
          {
            "name": "pbs-incremental-dirty-bitmap",
            "recording": true,
            "persistent": false,
            "busy": false,
            "granularity": 4194304,
            "count": 14432600064
          }
        ],
        "encrypted": false,
        "bps": 0,
        "bps_rd": 0,
        "cache": {
          "no-flush": false,
          "direct": true,
          "writeback": true
        },
        "file": "/dev/zvol/rpool/data/vm-12001-disk-1"
      },
      "qdev": "scsi1",
      "type": "unknown"
    }
  ]
}

I manually removed the dirty bitmaps on this VM:

Code: 
root@pve:/var/log# socat - unix-connect:/var/run/qemu-server/12001.qmp
{"QMP": {"version": {"qemu": {"micro": 0, "minor": 1, "major": 7}, "package": "pve-qemu-kvm_7.1.0-4"}, "capabilities": []}}
{     "execute": "qmp_capabilities",     "arguments": {}   }
{"return": {}}
{ "execute": "block-dirty-bitmap-remove",      "arguments": {        "node": "drive-scsi0",        "name": "pbs-incremental-dirty-bitmap"      }    }
{"return": {}}
{ "execute": "block-dirty-bitmap-remove",      "arguments": {        "node": "drive-scsi1",        "name": "pbs-incremental-dirty-bitmap"      }    }
{"return": {}}

Then the backup worked with "created-new" bitmaps:

Code: 
NFO: starting new backup job: vzdump 12001 --notes-template '{{guestname}}' --remove 0 --storage backup1 --node polaris --mode snapshot
INFO: Starting Backup of VM 12001 (qemu)
INFO: Backup started at 2023-01-16 08:29:08
INFO: status = running
INFO: VM Name: devops-builds-cosmos-preprod
INFO: include disk 'scsi0' 'local-zfs:vm-12001-disk-0' 55G
INFO: include disk 'scsi1' 'local-zfs:vm-12001-disk-1' 15G
INFO: backup mode: snapshot
INFO: ionice priority: 7
INFO: snapshots found (not included into backup)
INFO: creating Proxmox Backup Server archive 'vm/12001/2023-01-16T07:29:08Z'
INFO: issuing guest-agent 'fs-freeze' command
INFO: issuing guest-agent 'fs-thaw' command
INFO: started backup task '6253b91a-9e5a-49c9-b429-08f68ec285a8'
INFO: resuming VM again
INFO: scsi0: dirty-bitmap status: created new
INFO: scsi1: dirty-bitmap status: created new
INFO:  12% (8.5 GiB of 70.0 GiB) in 3s, read: 2.8 GiB/s, write: 256.0 MiB/s
...

I have other VMs stuck in the same state, anything that would be useful to PVE/PBS developpers to look at to find the source of this issue?


Thanks!
 
guerbywork said:
qmp command 'backup' failed - backup register image failed: command error: no previous backup found, cannot do incremental backup
Click to expand...
guerbywork said:
Code: 
INFO: include disk 'scsi0' 'local-zfs:vm-12001-disk-0' 55G
INFO: include disk 'scsi1' 'local-zfs:vm-12001-disk-1' 15G
Click to expand...

So I assume your root is on ZFS?
Do you also use the opt-in 6.1 kernel?
If yes, this might be the problem:
https://forum.proxmox.com/threads/o...ox-ve-7-x-available.119483/page-2#post-519762
(See my post above the linked one; I got exactly the same error message on backups.)
 
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