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?
Yes, but in the EC case, far smaller amounts of data will be sent to
each PG, so it depends on if you are calculating "amplification" in
terms of IOPS or in terms of MBytes (that needs to be sent over the
network and written to disk).
--
May the most significant bit of your life be positive.