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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.
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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.
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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
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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
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Establish A Naming Convention
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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.