[DRBD-user] UpToDate with out-of-sync data

[kvaps]

Hello, we periodically come across the problem.
The resource is shown as UpToDate, but for some reason it has several
unsynchronized bytes; this number does not change:

# drbdsetup status pvc—5Se9f359f-8939-46b5—99d0 at -S5e92c6db6b5f —-statistics
pvc—5e9f359f-8939-46b5-99d0 at -Se92c6db6b5f role:Secondary
  disk: UpToDate
      read:0 written:4968740
  kube-worker-dev-0 role:Primary
      peer-disk: UpToDate
          received: 43107880 sent:0
  kube-worker-dev-1 role:Secondary
      peer-disk: UpToDate
          received:543132 sent:0 out-of-sync:16

If I run `drbdadm disconnect / drbdadm connect` then everything
becomes fine. But it can randomly appear in other resources later.

DRBD version 9.2.4
Any ideas?

Best Regards,
Andrei Kvapil