[MongoDB] the solution of chunk too big to move
When the amount of data in some blocks is extremely large, forming a large block, Balancer cannot split the data block, and it cannot move the block. Using MongDB version 3.2, the solution is as follows:
1. Close Balancer first
sh.stopBalancer()
2. Query Mega Block
use configdb.chunks.find({jumbo:true})
3. Splitting Mega Blocks
sh.splitAt("db.collection", {shardkye:"split threshold"})
4. Move blocks manually (optional step)
sh.moveChunk("db.collection", {shardkey:"shardkey block"}, "target shard ID to move");
5. Restart Balancer
sh.startBalancer()
