How to combine collections (1GB per day) from data collection servers to the main server (backup)?

Question

MongoDB

Weak VPS servers convert the collected quotes, accumulating up to ~1GB.
What is the best way to transfer temporary information to a home disk, where the size of the hard disk is unlimited?
At home, the computer cannot work around the clock.
I planned to do this:
VPS:
1) collects quotes in mongoDB
2) transfers them to the main server once a day
3) clears (deletes?) the mongoDB database.
Home computer:
1) Accepts from 18h to 24h accumulated from the VPS and combines into a collection. (Thus, the size of the database will increase by an average of 1G per day.)
2) In the future, the database will be divided into shards.

Answer 1

You can transfer data via mongodump -> mongorestore, while data will be added on the destination server (provided that there are no _id collisions). You can also try the db.copyDatabase command.
Through ssh, you can make a tunnel , and dump directly to the local machine.
Although, for automatic collection, I would make an authorization by keys and put the script in cron, so that it would authorize itself and do a dump / restore. Along the way, you can do a quick compression via gzip, so that the data can be downloaded faster.
For example, something like this, makes a remote dump, presses, pumps to the local machine, unpacks and does a restore.

ssh -p 1022 server "cd /tmp/; rm -rf /tmp/dump.tbz2 /tmp/dump/; mongodump -d database; tar -cjf dump.tbz2 dump"
  rm -rf /tmp/dump/
  scp -P 1022 server:/tmp/dump.tbz2 /tmp/
  cd /tmp/; tar -xjf dump.tbz2; mongorestore

The compression itself can be done "on the fly" without creating a file.

Answer 2

rsync