Intro

My notes on VM computes

Documentation

• Virtual machines in Azure

• Availability options for Azure Virtual Machines

• Products available by region

Tips and Tidbits

• Virtual machines in Azure have two distinct names:

  • virtual machine name used as the Azure resource identifier, and

  • in guest host name.

  • When you create a VM in the portal, the same name is used for both the virtual machine name and the host name.

  • The virtual machine name cannot be changed after the VM is created.

    • You can change the host name when you log into the virtual machine.

• VM Max name length:

  • 15 characters on a Windows VM

  • 64 characters on a Linux VM.

• There are price differences between Azure regions so check prices

• Azure allows you to change the VM size when the existing size no longer meets your needs.

  • The VM size can be changed while the VM is running,

  • Changing a running VM size will automatically reboot the machine to complete the request.

• Keep in mind that Azure only supports 64-bit operating systems

• All Azure virtual machines will have at least two virtual hard disks (VHDs).

  • The first disk stores the operating system, and the second is used as temporary storage.

  • You can add additional disks to store application data;

    • the maximum number is determined by the VM size selection (typically two per CPU)

• The data for each VHD is held in Azure Storage as page blobs, which allows Azure to allocate space only for the storage you use.

Availability Zones

• An Availability Zone is a physically separate zone, within an Azure region.

  • There are three Availability Zones per supported Azure region.

• An Availability Zone in an Azure region is a combination of a fault domain and an update domain.

  • For example, if you create three or more VMs across three zones in an Azure region, your VMs are effectively distributed across three fault domains and three update domains.

  • The Azure platform recognizes this distribution across update domains to make sure that VMs in different zones are not scheduled to be updated at the same time.

SLA times

• SLA calculator: https://uptime.is/

SLA level of 99.9 % (3 nines) uptime/availability results in the following periods of allowed downtime/unavailability:

• Daily: 1m 26s

  Weekly: 10m 4s

  Monthly: 43m 49s

  Quarterly: 2h 11m 29s

  Yearly: 8h 45m 56s

SLA level of 99.95 % uptime/availability results in the following periods of allowed downtime/unavailability:

• Daily: 43s

  Weekly: 5m 2s

  Monthly: 21m 54s

  Quarterly: 1h 5m 44s

  Yearly: 4h 22m 58s

SLA level of 99.99 % (4 nines) uptime/availability results in the following periods of allowed downtime/unavailability:

• Daily: 8s

  Weekly: 1m 0s

  Monthly: 4m 22s

  Quarterly: 13m 8s

  Yearly: 52m 35s

SLA level of 99.995 % uptime/availability results in the following periods of allowed downtime/unavailability:

• Daily: 4s

  Weekly: 30s

  Monthly: 2m 11s

  Quarterly: 6m 34s

  Yearly: 26m 17s

• Design considerations for virtual machine creation

  • Availability: Azure supports a single instance virtual machine Service Level Agreement of 99.9% provided you deploy the VM with premium storage for all disks

Establish A Naming Convention

Names are not changeable after the VM is created so establish a good naming convention ahead of time to recognize machines.

For example, devusc-webvm01 might represent the first development web server hosted in the US South Central location.

VM Sizes

• Azure virtual machine sizes naming conventions

• Sizes for virtual machines in Azure

• A-Series v2 - Best suited for entry level workloads (development or test)

• B-Series - Ideal for workloads that do not need continuous full CPU performance, like web servers.

  • This series is burstable, meaning that when not in use, it accumulates credits which can be used when the workload increases.

  • B-series burstable virtual machine sizes

• D-Series v4 - The latest generation D family sizes recommended for your general purpose needs

  • D-Series v3 - The 3rd generation D family sizes for your general purpose needs

  • D-Series v2 - The 2nd generation D family sizes for your general purpose needs

• E-Series v4 - The latest generation E family sizes for your high memory needs

  • E-Series v3 - The 3rd generation E family sizes for your high memory needs

• F-Series v2 - Up to 2X performance boost for vector processing workloads

• H-Series - High performance compute VMs

• L-Series v2 - High throughput, low latency, directly mapped to local NVMe storage

  • This only one that provides NVMe storage.

Pricing Model

• Compute expenses are priced on a per-hour basis but billed on a per-second basis

• You are not charged for compute capacity if you stop and deallocate the VM since this releases the hardware.

• The cost for a VM includes the charge for the Windows operating system. Linux-based instances are cheaper because there is no operating system license charge

• You are charged separately for the storage the VM uses.

Azure has these models available

• Pay as you go - you pay for compute capacity by the second, with no long-term commitment or upfront payments. 

• Reserved Virtual Machine Instances -advanced purchase of a virtual machine for one or three years in a specified region.

  • The commitment is made up front, and in return, you get up to 72% price savings compared to pay-as-you-go pricing.

  • RIs are flexible and can easily be exchanged or returned for an early termination fee

• Spot Pricing - Purchase unused compute capacity at a discount.

  • Spot VMs are for workloads that can be interrupted, providing scalability while reducing costs.

• Azure Hybrid Benefit - For customers who have licenses with Software Assurance, which helps maximize the value of existing on-premises Windows Server and/or SQL Server license investments 

VM Storage

• Unmanaged disks: You are responsible for the storage accounts that are used to hold the VHDs that correspond to your VM disks.

  • You pay the storage account rates for the amount of space you use.

  • A single storage account has a fixed-rate limit of 20,000 I/O operations/sec.

    • This means that a storage account is capable of supporting 40 standard virtual hard disks at full utilization. 

• Managed disks: You specify the size of the disk, up to 4 TB, and Azure creates and manages both the disk and the storage.

  • You don't have to worry about storage account limits, which makes managed disks easier to scale out.

Boot Diagnostics

• Azure boot diagnostics

• Boot diagnostics is a debugging feature for Azure virtual machines (VM) that allows diagnosis of VM boot failures.

• Boot diagnostics enables a user to observe the state of their VM as it is booting up by collecting serial log information and screenshots.

• When creating a VM in Azure portal, boot diagnostics is enabled by default.

  • The recommended boot diagnostics experience is to use a managed storage account, as it yields significant performance improvements in the time to create an Azure VM

• Because the managed accounts are created on either Standard LRS or Standard ZRS, customers will be charged at $0.05/GB per month for the size of their diagnostic data blobs only. 

• User managed storage accounts associated with boot diagnostics require the storage account and the associated virtual machines reside in the same region and subscription and accessible from all networks.

  • Boot diagnostics does not support premium storage accounts or zone redundant storage accounts

• How to use boot diagnostics to troubleshoot virtual machines in Azure

• you can use the following debugging features: Console Output and Screenshot support for Azure virtual machines

• For Linux virtual machines, you can view the output of your console log from the Portal.

• For both Windows and Linux virtual machines, Azure enables you to see a screenshot of the VM from the hypervisor.

• The Boot diagnostics feature does not support premium storage account or Zone Redundant Storage Account Types.

Update Management

• You can use Update Management in Azure Automation to manage operating system updates for your Windows and Linux virtual machines in Azure, physical or VMs in on-premises environments, and in other cloud environments.

• Windows machines need to be configured to report to either Windows Server Update Services or Microsoft Update, and Linux machines need to be configured to report to a local or public repository.

• Enable Update Management

• Deploy Updates

Public IP Address and DNS Records

• A VM with a dynamic public IP address can have its DNS name entered into an Azure-provided DNS server.
  

• You can also create a CNAME mapping in your domain’s registrar to redirect your public domain to [dnsnamelabel].[region].cloudapp.net

Create an image of a VM using PowerShell

• Create an image of a VM using PowerShell

Virtual machine extensions

• Virtual machine extensions

• Windows VMs have extensions which give your VM additional capabilities through post deployment configuration and automated tasks.

• These common tasks can be accomplished using extensions:

  • Run custom scripts: The Custom Script Extension helps you configure workloads on the VM by running your script when the VM is provisioned.

    Deploy and manage configurations: The PowerShell Desired State Configuration (DSC) Extension helps you set up DSC on a VM to manage configurations and environments.

    Collect diagnostics data: The Azure Diagnostics Extension helps you configure the VM to collect diagnostics data that can be used to monitor the health of your application.