Second Hard Drive for MongoDB using directoryperdb

Question

Does anyone have any experience using directoryperdb? I can't find very many examples of its usage and would like to run my thought process past some knowledgeable people first :)

I've got a near terabyte database, and want to add another on a separate hard drive. I can't mess it up since reintegrating my data takes hours.

I currently have:

• --dbpath as /home/mongo
• A new nice empty hard drive mounted on /hd/newhd

My process is as follows:

1. Lets call the existing database old and the new one new.
2. mkdir /home/mongo/old
3. mv /home/mongo/* /home/mongo/old/
4. Symlink /home/mongo/new to /hd/newhd/newmongodb
5. vim /etc/mongod.conf ~ and set directoryperdb = true
6. restart mongod and start inserting data into a new db called new

Does this look OK? Will it just automatically recognize the new folders and continue as normal?

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Edit1: According to this: https://groups.google.com/forum/?fromgroups=#!topic/mongodb-commits/frAjIDG08Mc the mongod.lock file should be in /home/mongo. What about the journal or _tmp directory?

Answer 1

OK so I took the plunge and it worked fine~! :)

I'm now successfully saving data into the new db symlinked to the second HDD.

The only edit is that don't bother moving the journal folder into the db sub-directories as it will just be recreated in the main --dbpath

Hopefully someone else will find this post useful.