first of all please forgive me for asking a silly question but I am new to mongodb and just installed it on my windows platform by following this installation guide :http://docs.mongodb.org/manual/tutorial/install-mongodb-on-windows/
It says "MongoDB requires a data folder to store its files. The default location for the MongoDB data directory is C:\data\db.You can specify an alternate path for data files using the --dbpath option to mongod.exe."
So I created a folder d://data/db in my computer and issued a command
C:\mongodb\bin\mongod.exe --dbpath d:\mongodb\data
Then it says
"At the mongo.exe prompt, issue the following two commands to insert a record in the test collection of the default test database and then retrieve that record:
db.test.save( { a: 1 } )
db.test.find()"
I issued this to commands to save and retrieve the objects and its working fine but what is this default test database? where is it? Moreover where this object is stored? Where I can find this file?
what is this default test database?
When you connect to a mongod server without specifying a database, a default database "test" is selected. Since databases are created lazily, it may not even exist until you write to it.
db.test.save( { a: 1 } )
After this line is executed, database with current name ("test" by default) is created (if didn't exist already) and in it, collection "test" is created (if didn't exist already).
where is it? Moreover where this object is stored? Where I can find this file?
All databases are ultimately stored as files in your data dir. Look for "test.*" files there.
mongod.lock, is the file which provides the PID of your running mongod instance. When you start a mongod instance, MongoDB check if the lock is empty to start cleanly mongod. Then MongoDB registered the PID number of the running mongod instance in this lock file.
MongoDB delete the contains of this lock file when you shutdown cleanly your server,
mongod --shutdown -- dbpath <path name> --port <port number>
Related
I am running Mongo on Windows 10. Data access is made trugh Pymongo (Python). All my data is stored in an old large HDD, but I would like to have some smaller collection stored on a much faster SSD? When I create a new collection either trough Compass or Pymongo there is no option to specify the path on disk.
Is it possible to learn such power?
If you want to have databases in different disks under the same dbPath , this is the option:
Add the option --directoryperdb in the mongod config file or at startup.
db.createDatabase("newDatabase")
You will see inside the dbPath folder for the new database like:
\dbPath\newDatabase
Stop the mongodb process.
Copy the content from \dbPath\neWDatabase to your SSD let say:
ssd:\newData
make link to the folder with:
mklink /d \newData \dbPath\newDatabase
or follow this tutotial
Start the mongodb process again.
Note:
As suggested by #Wermfried in the comment it is safe to have the option --directoryperdb set initially in the member before to get populated ...
MongoDB documentation has the following line. What do they mean when they say, mongorestore can directly write to MongoDB data files without an active mongod? Does it mean it can write even if a mongod instance is not ready and reachable, or, is there something called inactive mongod instance. I am finding it difficult to understand. Can someone explain me this?
mongorestore can write data to either mongod or mongos instances, in addition to writing directly to MongoDB data files without an active mongod.
Prior to v3.x mongorestore could be configured to write directly to data files rather than writing into data files via mongod.
The term "data files" here refers to the contents of a dbpath directory so, by specifying --dbpath you could tell mongorestore to attach to the data files in that directory and insert data into those files without having to go through a mongod instance.
I'm completely new to MongoDB - I've installed all the programs and set it up so that I run mongod.exe and then mongo.exe. I created a new database called 'test' and inserted some data. However, I can't see any files being created in the /data/db directory. The data is definitely being stored somewhere, and when I closed down all the cmd boxes and started the processes again, the data I initially pushed onto the DB is still there.
I tried running the command 'db.adminCommand("getCmdLineOpts")' which apparently should show my DB Path, but it doesn't:
Can anyone offer some insight on this? Thanks :)
For using mongod.exe without parameters default is C:\data\db. Check start up parameters if you run server as service.
You can run this command to retrieve the dbpath if you in a Linux environment:
grep dbpath /etc/mongod.conf
db.adminCommand("getCmdLineOpts") is not running the db path as it was not specified a a command line parameter when the mongod process was started. It seems the db path is configured in the mongod.conf configuration file and the above command should return it.
I tried to connect to a local MongoDB instance, but it failed with error message Failed to connect.
I have run the commands shown in the below screenshots. The error message is shown there, too.
My folder structure is:
D:/mongodb/bin
D:/mongodb/data/db
D:/mongodb/log
I am using 32-bit Windows7.
Your data directory doesn't exist where MongoDB is expecting it to be.
For simplicity you can create D:/data/db, which is the default location and where mongod is looking at the moment, and use this as your data directory.
Alternatively if you want to use D:/mongodb/data/db as the data directory you'll need to specify the dbPath when starting mongod
mongod --dbpath D:/mongodb/data/db
This can also be done in a configuration file.
I have a mongodb installed on windows server. I take regular backups of the data/db folder using Rackspace backup.
I created a deployment of a mongodb replica set with 3 ubuntu servers using Rackspace deployments. Now I want to move the data on windows to the empty replica set. How can I do it?
I tried copying the contents of data/db on windows to var/lib/mongodb on the primary replica set. It didn't work.
For some reason the var/lib/mongodb on the ubuntu machines does not contain data/db directory. When I create a new db the db files are created on var/lib/mongodb directory.
The difference in data directories is fine .. on Windows the default dbpath will be c:\data\db; the Ubuntu package sets the dbpath to /var/lib/mongodb instead.
Since you are starting with an empty replica set (and using a backup from a standalone server), the most straightforward approach would be to:
Stop all the mongod servers for the replica set (you definitely don't want to copy data files directly into a running instance!).
Remove any files that are already in the /var/lib/mongodb data directory.
Copy the data files from your standalone MongoDB backup into /var/lib/mongodb on one of your replica set servers. This server will become your primary to set up the rest of the replica set.
Start up this primary making sure to include a replSet name in your configuration file. You may already have this set from your "empty" replica set that you already created.
Run rs.initiate() in the mongo shell to create the initial configuration on the primary.
Start up your additional servers as members of this replica set: they need the same replSet name configured.
Use rs.add(..) to add your additional servers from the mongo shell on your primary. Assuming the add is successful (i.e. the mongods can connect to each other), this will begin the process of initial sync (copying data from the primary) and the new hosts will become secondaries after they have finishing initial sync.
This is essentially the same steps as the deploy a replica set tutorial, except you are copying over your data first.
The problem could be related to the configuration file of mongodb
locate the file mongodb.conf and edit the dbpath parameter, check if the path really exist, and if it doesn't create the missing directories. Also check permissions in that path
anyway i don't know if its the right way to just copy the datafiles in a new location, i guess you should use mongo import/export