Managing chunk size

As mentioned earlier in the previous chapter, the chunk is the lowest block of data the sharded cluster balancer can manage. Normally, the sharded cluster balancer automatically creates a new chunk when it has grown past the default (or assigned) chunk size. The default chunk size is 64 megabytes (MB). Documents are then migrated between chunks until a balance occurs. Further, with zone-to-shard assignments in mind, the balancer also migrates chunks between shards to maintain a balanced load. 

There are several approaches to managing chunk size: adjusting the chunk size, which triggers the automatic balancing process; or, manually splitting chunks. Let's now have a look at adjusting the chunk size.