Mongo DB Replicat Sets1. No master.

2. Add & Remove members dynamically

3. Automated failover

4. Vote to decide who will be Primary.

Arbiter nodes can be added.

5. Read scability

6. Disaster recovery

7. Using oplog to recover(current limitation

oplog size cannot change after creaion)

Replicate sets = Active physical standby +

Data Guard Fast Start Failover + …,

looks good, huh?

Mongo DB Sharding + Replicat sets

Call mongod and collect result.

1. Add & remove nodes

dynamically

2. Auto split/move data. (also

support manually split)

3. Blancer process: by chunk

64MB by default, can be

stopped manually

1. Can be Single server or

Replicat Set.

2.Add and remove sharding

nodes dynamically.

3. Dynamic Range partition.

4.Can be DB(schema) level

or collection(table) level

5.Across data center is

possible.

1. Record Sharing metadata

2.Use a two phase commit . One

down, all read-only

3.Add config server need to

shutdown all.

4. Replace a config server online

if possible by switching DNS

Sharding = Auto unlimited(1000) range partition

among servers + Auto balance + …, not bad?