CODEWITHSUNDEEP
mongodb
Sandeep
Sandeep

Reputation: 546

mongo DB Balancing

I have a collections with a shard key and index endabled. But when I run balancing, the chunks are not moved for this collections where as the other collection chunks are moving as expected to other machines. Only one chunk is moved from this collection.

Upvotes: 2

Views: 1362

Answers (1)

Adam Comerford
Adam Comerford

Reputation: 21682

Currently (this will change in the near future), the balancer will only start moving chunks when there is a sufficient imbalance (8 or more). If the chunk counts are closer than that, then there will be no movement. The number of chunks is dependent on the max chunk size (64MB at the time of writing this in 2.0.x) and the amount of data written. There is a split triggered every time a certain amount of data is written to a chunk.

So, if you are not adding data to the collection, or the data is not very large, it can take some time to create the number of chunks necessary yo trigger a balancing round.

You can take this into your own hands by manually splitting and moving a chunk:

http://www.mongodb.org/display/DOCS/Splitting+Shard+Chunks

Or, you can add more data to trigger splits and the balancer will eventually kick in and move the chunks around for you.

Upvotes: 2

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