Scalability and High Availability with ReplicaSet

@vparihar

Vivek PariharAVP Engineering,Weboinse Lab

Who Am I?● A Weboniser and Rubyist● Blogger(vparihar01.github.com)● MongoDb user● Geek● DevOps● Mainly write Ruby, but have great passion for Javascript

and Cloud Platforms● ...

Agenda● {10: Reasons, To: Love }● Scalability with ● What is Sharding?● What is Replica Set?● Replication Process● Advantaged of Replica Set vs Master/Slave ● How to set up replica set on production

{10: Reasons , To: Love } I.RELATIVELY EASY TO SETUP

In simple 3 steps MongoDb is start running on your machineStep-1. sudo apt-key adv --keyserver keyserver.ubuntu.com --recv 7F0CEB10

Step-2. sudo apt-get install mongodb-10gen

Step-3. sudo /etc/init.d/mongodb start

{10: Reasons , To: Love } II.It’s fast

On average 7 times faster

{10: Reasons , To: Love } III. Easy Scalability

{ Does Anyone know about scaling MySql? }

{10: Reasons , To: Love } IV. High Availability

{10: Reasons , To: Love } V. High Performance

{10: Reasons , To: Love } VI. Flexible Schema{no schema: no problem}

{10: Reasons , To: Love MongoDb} VII. Built in Sharding and Replication

{10: Reasons , To: Love } VIII. Courses are excellent to start working as a

developer/DBA with.

{10: Reasons , To: Love } IX. Deploy New Instances on Demand

{10: Reasons , To: Love } X. BASE Rather Than ACID

ACID BASE

Atomicity Basically Available

Consistency Soft State

Isolation Eventual Consistency

Durable

Horizontal Scaling Vs Vertical Scaling

Scalability with ● Horizontal Scaling● Auto-Sharding● Vertical Scaling● Replica Set● Performance {For: Read, For: Write}● Storage

Horizontal Scaling● By adding more machines into the existing pool.

● In a database world horizontal-scaling is often based on partitioning of the data i.e. each node contains only part of the data.

● MongoDB achieves this through auto-sharding.

Vertical Scaling● Typically refers to adding more processors ,ram and

storage to a Symmetric Multiple Processing to extend processing capability.

● In a database world vertical-scaling is done through multi-core i.e. spreading the load between the CPU and RAM resources of that machine.

What is Sharding?● Sharding is a method for storing data across multiple

machines.

● Also known as Horizontal Scaling

● Divides the data set and distributes the data over multiple servers, or shards.

What is Sharding?Each shard is an independent database, and collectively, the shards make up a single logical database.

Sharding offerings:● Automatic balancing for changes in load and data

distribution● Easy addition of new machines● Scaling out to one thousand nodes● No single points of failure● Automatic failover

What is Replication?● Replication is the process of synchronizing data across

multiple servers.● Mongo achieves Replication through Replica Sets● Replica sets are a form of asynchronous master/slave

replication● A replica set consists of two or more nodes that are

copies of each other. (i.e.: replicas)

Purpose of Replication Data Redundancy ● Replica sets provide an automated method

for storing multiple copies of your data.

Purpose of Replication Automated Failover / High Avalability ● If primary fails then replica set will

attempt to select another member to become the new primary.● This means that the failure of a

primary can be handled by the client without any configuration changes● Use heartbeat signal to detect failure

Purpose of Replication ● Distributed Read Load/Read Scaling

By default, the primary node of a replica set is accessed for all reads and writes.

● Disaster RecoveryReplica sets allows for a “delayed secondary” node. This node can provide a window for recovering from disastrous events such as:

○ bad deployments ○ dropped tables and collections

Replication Process● Members of a replica set replicate data continuously● MongoDB applies database operations on the primary

and then records the operations on the primary’s oplog. ● All replica set members contain a copy of the oplog,

allowing them to maintain the current state of the database.

Advantages of Replica Set vs Master/Slave

● Replica sets are basically just master-slave with automatic failover.

● So, you have a pool of servers with one primary (the master) and N secondaries (slaves). If the primary crashes or disappears, the other servers will hold an election to choose a new primary.

Demo -: How to set up replica set on Production!

Click on below link to see the demo-:

http://youtu.be/BFSGcBHcirU

Thanks

Would Love to answer your queries...

Vivek Parihar@vparihar