Mongo repairDatabase procedure

Question

I need to run a repairDatabase in mongo in order to reclaim some os disk space. Can anyone provide feedback on the following procedure: let me know if its correct, if I'm missing anything, if the steps are in order, etc.

The setup is a primary/secondary on separate servers. They are both about out of disk space. My plan is to repair the database on each one separately after the other completes. As I am out of disk space, I will be using an external block storage from my cloud provider to use as a repair path. Mongo is currently running via sudo service mongodb start. To complete this it seems that I'll run the following:

• On the primary I step down using rs.stepDown()
• I shutdown mongo using rs.shutdownServer() - Is this correct? For the next step it seems that I shouldn't run it if Mongo already has another instance running.
• On the primary I run mongod --config /etc/mongodb.conf --repair --repairpath PATH_TO_BLOCK_STORAGE
• When complete, do I need to copy the data in the repair path over to the original (/var/lib/mongodb)?
• Once back up, I restart Mongo using sudo service mongodb start
• I then wait for the oplogs to catch up and for the mongos to be in sync.
• Once they primary and secondary are in sync I then go onto mongodb-perf-02 and run rs.stepDown() so that mongodb-perf-01 is the primary again.
• Once complete I then repeat this on the secondary.

Answer 1

The solution to this issue was as follows: Starting with the secondary:

Inside of Mongo I ran the following:

db.shutdownServer()
exit

On the command line:

rm -rf /var/lib/mongodb/*
sudo service mongodb start

It then takes a couple of hours to resync. Once resynced I did the following on the primary:

rs.status() //To make sure that the everything was synced
rs.stepDown(9200)
db.shutdownServer()
exit

On the command line I ran:

rm -rf /var/lib/mongodb/*
sudo service mongodb start

Then in Mongo I ran:

rs.status() //To make sure that everything was synced
rs.freeze(0) //To remove the re.stepDown(9200) lock

On the secondary I ran:

rs.stepDown()

Note: If possible, back up all of your data first.