Same issue we are facing in couchbase 4.1.0 CE version.
The number of documents = 26060149. backup time took 10 hours to reach 66.30%.
below is the log info
[############# ] 66.3% (26059957/estimated 39309053 msgs)^[[A
bucket: ptxdata, msgs transferred…
: total | last | per sec
byte : 173941781498 | 173941781498 | 4777396.5
2016-10-18 00:05:37,625: mt could not find index server:0
done
can anyone please provide detailed info of the same.