title: MongoDB replica member which is only online once a day
body: <p>I have a low power consumption/low performance (Brasswell=Atom) 24/7 MongoDB database server on one hand, and on the other a high power consumption/high performance (Xeon) backup server which is usually only powered on once a day for about 10 minutes. It's not backing up the MongoDB data because no steps have been taken for this to be done.</p>
  
  <p>Does it make sense to create a replica set on the Braswell, add an arbiter on the Brasswell, and then create a priority=0 replica member on the Xeon, so that it backs up the Brasswell whenever it comes online? Since it's a priority=0, would it even be possible to ditch the arbiter?</p>
  
  <p>If it would work, would I have failing inserts on the primary for a short moment when the Xeon goes offline?</p>
  
  <p><strong>Extra Info</strong>: This is a private database, as in "it does not store any information which would require a special care against attacks or loss". It stores lots of data from consumer-grade IoT devices, in order to track the usage/sensor data as well as their phoning-home behaviour.</p>
  
  <p>I'm not sure if delaying it is neccessary, but it probably would make sense to add a 1 day delay.</p>
  
  <p>Backing up via filesystem snapshots is not an option. Using mongodump / copy / restore would be an option and also give me a second local backup, but I'm not sure if I want to do that (handle the automation of that)</p>
  
  <p>As this secondary would get a priority of 0, it would never get considered for election and, adding to that, the scenario of having the primary fail while the secondary is online is very unlikely, as in</p>
  
  <p>¯\_(ツ)_/¯</p>
  
  <p>if that happens.</p>