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Zango
Zango

Reputation: 2387

MongoDB active diaglog file gets too big

I have a mongodb replica set. Data file sizes are quite big because there is many write operations. One mongodb node crashed because of lack of disk space because one diaglog file was 38GB.

Is there any way that diaglog files didn't get so big and instead it created multiple small(2GB or 4GB) files and then i would be able to delete unused ones?

Upvotes: 1

Views: 2526

Answers (2)

Stennie
Stennie

Reputation: 65303

The diaglog parameter is not required for replica sets. It creates a very verbose log for troubleshooting purposes, and should definitely not be enabled by default.

You can safely remove this parameter from your mongod configuration and also remove the diaglog.* files in your dbpath.

I suspect you are confusing the diaglog output with the replication oplog (operations log). The oplog is stored in the local database in a collection called oplog.rs, and is preallocated when you initialise your replica set. The oplog size is 5% of free disk space by default for most 64-bit operating systems; there are some exceptions for OS X and 32-bit systems as noted in the MongoDB manual.

Upvotes: 1

Neil Lunn
Neil Lunn

Reputation: 151072

The files should only be present where there server is a config server or where the command line option has been explicitly set when starting mongod.

--configsvr or --diaglog

As this is intended for diagnosing specific problems you probably don't want this turned on all the time. In which case, remove the --diaglog option from startup unless you specifically put it there.

So the point is, the --diaglog option exists for the purpose of very verbose logging in order for you di diagnose problems. It should not be generally used in production environments.

If you really want it, then you are looking at log rotation and archiving methods that are a bit out of scope for the type of questions asked here.

See the documentation.

Upvotes: 2

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