Making VarnishHighly Available

Varnish Varnish

Load balancer

Web server

Client

What happens when a cache fails

• Cached objects are not available

• Backend traffic surges

• Page load time spike

What is VHA?

• High availability for Varnish Plus

• Circular, multi-master replication

• Does not require additional HA components

Why Varnish HA?

• Increases resiliency of caching layer

• Big overall performance increase

Applicability

• Business critical Varnish Plus installations

• Any multi-cache Varnish setup

• Two/three node CDN POP installations

How does it work?

Varnish Varnish

Load balancer

Web server

Replicationstream

Client

Functionality walkthrough

Varnish Varnish

Load balancer

Web server

Client

Replication

Implementation

• Memory impact is less than 100M. Threaded architecture with 10 threads as the default

• Statistics are delivered through a file.

• Capacity is ~ 1000 objects/sec with default configuration

Summing up

• Non disruptive high availability

• Increases performance

• Adds resilience

Q & A