Compute - Oracle Cloud Infrastructure - Architect Associate(1Z0-1072-20)

  Oracle Cloud Infrastructure Architect Associate exam tests varieties of topics like

1. Identity and Access Management
2. Networking
3. Compute 
4. Storage
5. Database

A good place to learn about the topics are

https://docs.oracle.com/en-us/iaas/Content/home.htm

And there is a book specifically written for the exam and is available in Oreilly

https://learning.oreilly.com/library/view/oracle-cloud-infrastructure/9781260452600

In this blog, I am sharing the notes I have taken for the topic 

Compute 

Compute Service

• Bare metal - customer gets direct hardware access also called as single tenant model
• Virtual Machine - an hypervisor is adder to virtualize the baremetal and shared to many tenants - also called as multi-tenant model
• Dedicated VM hosts - Runs VMs with on top of the baremetal and customer can manage it
• OCPU - provides CPU capacity equivalent to one processor with hyper-threading enabled

Images:

• Can be linux, windows or any other image by the provider
• Different images
• Platform images
• Oracle Images
• Partner Images
• Custom Images
• Boot Volumes
• Images OCID
• BYOH (Bring Your Own Hypervisor)
• Custom Image
• User can create custom images where they can have patch, specific version etc
• Restriction in custom image are
• that total size cannot exceed 300 Gb
• block volumes cannot be attached
• windows custom image cant be downloaded  out of the tenancy
• for other OS, we can do import and export of custom image to other tenancies using the object store
• 3 modes
• Emulated - everything is a s/w including CPU, memory, IO etc and it is slower
• Paravirtualized - includes driver to enable virtualization
• Native - same as Harware Virtualized Machine (HVM) and offers maximum performance
• Boot Volumes
• An instance is launched using OS image stored in boot volume
• Is the volume where OS boot image will be stored
• Is a special kind of block volume
• We can preserve the boot volume when we terminate the compute instance
• Boot volumes cannot be detached from running instance
• Boot volumes are terminated only when manually deleted
• We can choose custom boot volumne size and max we can go till 32 TB
• Custom image vs Boot volume
• Only either of them is possible - boot backup or boot clone

Instance Configuration, pools, Auto scaling

• Instance Configuration - is like a snapshot of metadata, including its vNIC, subnet etc
• Instance Pool - Using the configuration we can spin up multiple instance across regions, ADs etc
• Autoscaling - scale up or down based on the threshold
• The policy supported for threshold is CPU and memory

Instance Metadata

• Include OCID, name, compartment, shape, region, AD, state etc
• Metadata service runs on every instance and it is accessible fro 169.254.169.254
• Instance Lifecycle - Start, Stop, Restart, Terminate
• Instance Action: START, STOP, RESET, SOFTRESET, SOFTSTOP
• How to troubleshoot an instance - to use bootvolume as data volume

Container Engine for K8S

• Three ways to run a containe
• Roll your own - setting up everything on top of IaaS
• QuickStart Script - Terraform script to bring up all the necessary component on IaaS
• OKE - Container as a Service