Compute: VMs

Question 1

Virtual Machine Extensions

Answer 1

Small applications that provide post-deployment config and automation tasks on Azure VMs.

(e.g., software installation, anti-virus protection, configuration script inside)

Question 2

Naming VMs

Answer 2

A good convention is to include environment, location, instance, product/service, role.

(e. g., devusc-webvm01) dev environment, located in US south central, for web dev
(e. g., prodausse-sql03) prod in Australia south east, for sql, 3rd instance.

Question 3

VMs - Compute costs

Answer 3

Priced per hour
Charged per minute

Stopping and deallocating a VM releases the hardware and incurs no cost

Question 4

VM Storage costs

Answer 4

Charged for the storage a VM uses.

Status of VM has no relation to storage charges (i.e., a stopped/deallocated VM still incurs storage costs)

Question 5

VMs disks

Answer 5

All Azure VMs have at least two disks.

OS disk (C:\)
Temp disk (D:\)
Can have one or mare data disks

Question 6

Connecting to virtual machines - windows os

Answer 6

Remote Desktop Protocol (RDP) - establish a GUI

Windows Remote Management (WinRM) - establish a command line session to an Azure VM that runs any supported version of windows.

Question 7

connecting to virtual machines (linux)

Answer 7

SSH is an encrypted connection protocol that allows secure sign-ins over unsecured connections. SSH is the default connection protocol for Linux VMs hosted in Azure.

Question 8

VMs : Update Domain

Answer 8

An update domain (UD) is a group of nodes that are upgraded together during the process of a service upgrade (rollout).

Question 9

VMs: Fault Domain

Answer 9

A fault domain (FD) is a group of nodes that represent a physical unit of failure. A fault domain defines a group of virtual machines that share a common set of hardware, switches, that share a single point of failure.

Question 10

Availability Zones: Zonal Services

Answer 10

Pins the resource to a specific zone (for example, virtual machines, managed disks, Standard IP addresses).

Question 11

Availability Zones: Zone-redundant services.

Answer 11

Platform replicates automatically across zones (for example, zone-redundant storage, SQL Database).

Question 12

Custom Script Extensions (CSE)

Answer 12

used to automatically launch and execute virtual machine customization tasks post configuration.

Your script extension may perform simple tasks such as stopping the virtual machine or installing a software component. However, the script could be more complex and perform a series of tasks.

Question 13

Desired State Configuration (DSC)

Answer 13

is a management platform in Windows PowerShell. DSC enables deploying and managing configuration data for software services and managing the environment in which these services run.

Question 14

Containers vs VMs: Isolation

Answer 14

Container: lightweight isolation from the host and other containers

VMs: Complete isolation from the host OS and other VMs (strong security boundary)

Question 15

Containers vs VMs: OS

Answer 15

Containers: Runs the user mode portion of an operating system and can be tailored to contain just the needed services for your app.

VMs: Runs a complete operating system including the kernel, thus requiring more system resources (CPU, memory, and storage).

Question 16

Containers vs VMs: Deployment

Answer 16

Containers: Deploy individual containers by using Docker via command line; deploy multiple containers by using an orchestrator such as Azure Kubernetes Service.

VMs: Deploy individual VMs by using Windows Admin Center or Hyper-V Manager; deploy multiple VMs by using PowerShell or System Center Virtual Machine Manage

Question 17

Containers vs VMs: Persistent Storage

Answer 17

Containers: Use Azure Disks for local storage for a single node, or Azure Files (SMB shares) for storage shared by multiple nodes or servers.

VMs: Use a virtual hard disk (VHD) for local storage for a single VM, or an SMB file share for storage shared by multiple servers.

Question 18

Containers vs VMs: Fault Tolerance

Answer 18

Containers: If a cluster node fails, any containers running on it are rapidly recreated by the orchestrator on another cluster node.

VMs can fail over to another server in a cluster, with the VM’s operating system restarting on the new server.