The cancels value of the replication counters of the first secondary increases steadily.

And the disk utilization value of secondary server is 10% higher than primary and hidden secondary.

test langunge : java (mongo java driver 2.13.2 & 3.5), python (pymongo 3.4)
file format : xfs

config = {
_id : "rs1",
protocolVersion: 1,
writeConcernMajorityJournalDefault: true,
members: [
{ _id:0, host:"mongod1rs1:31001",priority:3 },
{ _id:1, host:"mongod1rs2:31001",priority:3 },
{ _id:2, host:"mongod1rs3:31001",priority:0,hidden:1 }
],
settings: {
chainingAllowed: 1
}
};
rs.initiate(config);

--> Even if the chainingAllowed option is set to 0, it is the same.