Why load balancing matters in Azure - Visual Breakdown

Process Flow - Why load balancing matters

User sends request

↓

Load Balancer receives request

↓

Check server health

↓

Distribute request to healthy server

↓

Server processes request

↓

Response sent back to user

↓

Monitor server load and health

↩Back to Load Balancer for next request

Requests from users go to the load balancer, which checks server health and sends requests only to healthy servers, ensuring smooth and reliable service.

Execution Sample

Azure

User -> Load Balancer -> Server1 or Server2 -> Response

Shows how a load balancer directs user requests to one of multiple servers and returns the response.

Process Table

Step	Action	Load Balancer Decision	Server Status	Result
1	User sends request	Receives request	Server1: Healthy, Server2: Healthy	Request accepted
2	Load Balancer checks servers	Both servers healthy	Server1: Healthy, Server2: Healthy	Ready to distribute
3	Load Balancer distributes request	Sends to Server1	Server1: Healthy	Request sent to Server1
4	Server1 processes request	N/A	Server1: Processing	Response generated
5	Response sent back	N/A	Server1: Healthy	User receives response
6	Next request arrives	Receives request	Server1: Healthy, Server2: Healthy	Request accepted
7	Load Balancer checks servers	Server2 is busy, Server1 healthy	Server1: Healthy, Server2: Busy	Ready to distribute
8	Load Balancer distributes request	Sends to Server1	Server1: Healthy	Request sent to Server1
9	Server1 processes request	N/A	Server1: Processing	Response generated
10	Response sent back	N/A	Server1: Healthy	User receives response
11	Server2 recovers	N/A	Server2: Healthy	Ready for requests
12	Load Balancer distributes next request	Sends to Server2	Server2: Healthy	Request sent to Server2
13	Server2 processes request	N/A	Server2: Processing	Response generated
14	Response sent back	N/A	Server2: Healthy	User receives response
15	No more requests	N/A	N/A	Execution ends

💡 No more user requests to process, load balancer waits for new requests

Status Tracker

Variable	Start	After Step 3	After Step 8	After Step 12	Final
Server1 Status	Healthy	Processing	Processing	Healthy	Healthy
Server2 Status	Healthy	Healthy	Busy	Processing	Healthy
Load Balancer Target	None	Server1	Server1	Server2	None

Key Moments - 3 Insights

Why does the load balancer check server health before sending requests?

To avoid sending requests to servers that are down or busy, ensuring users get a quick and reliable response as shown in steps 2 and 7.

What happens if one server is busy but the other is healthy?

The load balancer sends the request to the healthy server, as seen in step 7 where Server2 is busy and Server1 receives the request.

Why is it important that the load balancer distributes requests evenly?

To prevent any single server from becoming overloaded, which keeps the system stable and responsive, demonstrated by alternating targets in steps 3, 8, and 12.

Visual Quiz - 3 Questions

Look at the execution table, which server does the load balancer send the first request to?

A Both servers

B Server1

C Server2

D No server

💡 Hint

Check Step 3 in the execution table where the load balancer distributes the request.

At which step does the load balancer send a request to Server2?

A Step 12

B Step 7

C Step 3

D Step 5

💡 Hint

Look at the Load Balancer Target column in variable_tracker after Step 12.

If Server1 becomes unhealthy, how would the load balancer behave?

A Stop sending requests

B Send requests randomly

C Send all requests to Server2

D Send requests to Server1 anyway

💡 Hint

Refer to the key moment about checking server health before sending requests.

Concept Snapshot

Load balancing directs user requests to multiple servers.
It checks server health to avoid sending requests to busy or down servers.
This ensures reliability and better performance.
Load balancers distribute requests evenly to prevent overload.
If a server fails, traffic shifts to healthy servers automatically.

Full Transcript

Load balancing is a process where incoming user requests are received by a load balancer. The load balancer checks which servers are healthy and ready to handle requests. It then sends each request to one of these healthy servers. This helps keep the system reliable and fast because no single server gets overloaded. If a server becomes busy or unhealthy, the load balancer stops sending requests to it and uses other servers instead. This way, users get quick responses and the service stays available.