[ceph-users] Write amplification for CephFS?

Dear all, is there information available anywhere about the write amplification for CephFS? I found quite some material on write amplification of VMs using journaled file system on top of RBD but nothing as it relates to CephFS? From my understanding I would expect the following: - for X-rep, data needs to be written to X pgs (factor X) - for k-m EC, data is written to k+m pgs (factor (k+m)/k) Am I correct? How much is added by meta data, WAL? Do I miss anything? Best wishes, Manuel