System Design Handbook

Handling Failures

Mon, 01 Jan 0001 00:00:00 +0000

Handling failures#

This blog is part of a series on robust system design. Check the other posts that address scalability, failures, latency and integration.

Introduction#

A large system consists of an end-user application (mobile, web) calling an exposed API. This API will translate into a number of internal and external API calls. We are considering the synchronous part of the system only: the services that are directly used by the API call.

Handling overload

Mon, 01 Jan 0001 00:00:00 +0000

Handling overload#

Any system has a specific maximum capacity under a certain type of workload. The underlying virtual or physical hardware limits this capacity.

Origins#

The major components with hard limits are:

Processor: if too many processes are competing for CPU time, there will come a time when the operating system scheduler will have to pause certain processes and delay them.
Memory size: memory is different from processor and disk in the sense that it is a hard limit. If a process cannot allocate memory, it will simply crash. Operating system delay this from happening by using swap: using disk as a trade-off between speed and crashes.

Availability

Mon, 01 Jan 0001 00:00:00 +0000

Availability#

This blog is part of a series on robust system design. Check the other posts that address scalability, failures, latency and integration.

Introduction#

In today’s digital landscape, where businesses and users expect seamless, uninterrupted access to services, ensuring high system availability is a critical concern for IT organizations. Modern IT systems comprise numerous interdependent components that exchange information, and their collective availability directly impacts the overall user experience and business continuity.

Scalability

Mon, 01 Jan 0001 00:00:00 +0000

Scalability#

Understanding system scalability is crucial for building robust applications. This post explores the qualitative and quantitative approach to system. Before diving into the mathematical aspects of system scaling, let’s understand the two fundamental approaches to scaling: vertical and horizontal.

Understanding Scaling Approaches#

Vertical Scaling (Scaling Up)#

Vertical scaling involves adding more power to your existing infrastructure. Think of it as upgrading your machine’s capabilities:

Resources Enhanced:
- CPU: Adding more processors
- Memory: Increasing RAM capacity
- Storage: Expanding throughput (MB/s) and performance (iops)
- Network: Increasing bandwidth (Gb/s)
Advantages: