delivery of computing services—including servers, storage, databases, networking, software, analytics, and intelligence—over the Internet

Cloud has 3 types - Public, Private, Hybrid cloud
Benefits : cost, global scale, speed, productivity, performance, reliability, security
**Public cloud** - shared infrastructure (servers, storage, routers, switches) used across clients and that can be scaled up or down easily as per requirement. owned and operated by third party - Azure, AWS, GCP
**Private cloud** - shared physical site of datacenter, however, infrastructure is allocated for to specific clients. Full compliance, privacy as far as data stored in the cloud goes. Control of physical infrastructure and maintaining security/compliance is with private cloud provider. cloud computing resources used exclusively by a single business or org. Services and infra is maintained on a private network.
**On premise datacenter** - Privately owned infrastructure that will be managed by client. Full control, compliance, privacy.

### Hybrid cloud - 
combines public and private cloud technologies, can move data between private and public clouds freely, to optimize for performance, flexibility, security and compliance.
- **Cloud bursting** - Client with existing on-prem infrastructure sees spike in traffic, then client uses public cloud for some time
- **Data protection** - database is stored on-premise, application on public cloud
- [[Dell Hybrid cloud]]
	1. Replicate same workload across multiple clouds - multiple data centers globally, providing redundancy (increased availability) as well as CDNs (offer content where the user is to offer increased performance)
	2. Split workload across multiple clouds - for example
		1. Use AWS for web app
		2. Use GCP for big data and analytics
		3. And use Azure for Microsoft Office products & file storage
	- Tradeoffs of multi-cloud - 
		- Multiple environments to manage, each cloud provider will have their own APIs
		- Migration may not be easy, re-architecture may be needed. 
		- Vendor lock-in can create issues in future (can be avoided with Kubernetes clusters)

### Components of data center -
- Compute
- Storage
- Networking
- Telemetry monitoring
- Cooling and power management system

### Types of as-a-service (aaS)
Cloud computing has 4 types -
- IaaS - rent IT infra on pay as you go basis. Servers, VMs, storage, networks, OS.
- PaaS - Provide services for on-demand developing, testing, delivering and managing software apps. Customers don’t need to worry about underlying infrastructure.
- Serverless computing - Cloud provider handles setup, capacity planning and server management. Provides scalable, event-driven architecture.
- SaaS - delivering software apps over the internet, on demand, typically for a subscription. Cloud provider manages everything from software, to underlying infra, including maintenance, security, software upgrades.
![[Types of aaS.png|1200]]
### Infrastructure spend in IT
![[Pasted image 20230331082649.png|750]]
![[Pasted image 20230331082546.png|750]]
