This blog post will go through some quick tips including Q/A and related blog posts on the topics that we covered in the Azure Admin Day 5 Live Session which will help you gain a better understanding and make it easier for you to
In this blog, I am going to share some quick tips including Q/A and useful links from Day 5 of Azure Admin covering Module 6: Azure Virtual Machines where we have covered topics like Azure VMs, SLA for Virtual Machines, VM Extensions, VM Scale Sets, Azure Snapshot.
Azure Virtual Machines
A Virtual Machine (VM) is a computing service that performs most functions of a physical computer, actually behaving like a separate computer system. A virtual machine, usually known as a guest, is created within another computing environment (i.e., Physical Datacenters) referred to as a “host”
An Azure VM gives you the flexibility of virtualization without having to buy and maintain the physical hardware that runs it. However, you still need to maintain the VM by performing tasks, such as configuring, patching, and installing the software that runs on it.
Uses of Virtual Machines
- A virtual machine can overturn our current operating system. This is a good use of VMs, existing operating systems we use can be restored from virtual machines.
- Applications are developed and deployed in the cloud, and virtual machines can be used to develop and deploy applications in the cloud.
- The virtual machine can be used to run many applications and software in processes for which it was not designed.
- There are many applications and software that are not designed for specific operating systems, but in such cases virtual machines can be used to solve these problems.
- Azure DevTest Labs uses virtual machines to test and run more software than existing projects.
- They created a new environment that makes it easy for developers to create test cases for development.
- Another advantage of the virtual machine is that whenever a new operating system is released, it is first tested on a virtual machine to ensure it is tested and working.
Before Creating a Virtual Machine
Before we create a virtual machine in Azure, we need to understand some important concepts.
- We need to decide on the name of the application we are dealing with. The filename of the application we are working on must be correct.
- The second step is that we need to determine the location of the virtual machine. It means where our resources are stored.
- Then let’s determine the size of the virtual machine according to our work.
- should also determine which operating system the virtual machine is running.
- We need to know all the settings of the virtual machine we created on Azure.
Network Interface Card (NIC)
A Network Interface (NIC) is an interconnection between a Virtual Machine and the underlying software network. An Azure VM has one or more network interface cards (NICs) attached to it.
Network Interface Card (NIC) is assigned with IP address and associated with NSG rules, which is used for the communication between virtual machines or internal network or internet.
High Availability options for Azure Virtual Machines
An Availability Zone is a high-availability offering that protects your applications and data from data center failures. Availability Zones are unique physical locations within an Azure region.
An availability set is a logical grouping of VMs that allows Azure to understand how your application is built to provide for redundancy and availability.
Read more on Availability options for Azure Virtual Machines
Q1: How many VM we can put in one Resource group?
Ans: Each resource group can hold up to 240 VMs.
Q2: Can multiple people use the same VM?
Ans: You can have multiple users access the same VM, just one at a time.
Q3: How many NICs can we attach with a VM?
Ans: Virtual machines (VMs) in Azure can have multiple virtual network interface cards (NICs) attached to them. A common scenario is to have different subnets for front-end and back-end connectivity. You can associate multiple NICs on a VM to multiple subnets, but those subnets must all reside in the same virtual network (vNet).
Q4. Can we add an existing VM to an availability set?
Ans. No. If you want your VM to be part of an availability set, you need to create the VM within the set. There currently isn’t a way to add a VM to an availability set after it has been created.
Q5. Can we add a NIC to my VM after it’s created?
Ans. Yes, this is now possible. The VM first needs to be stopped or deallocated.
Service Level Agreement (SLA)
Service-level agreements (SLAs) describe Microsoft’s commitments for uptime and connectivity.
SLA for Virtual Machines
- For all Virtual Machines that have two or more instances deployed across two or more Availability Zones in the same Azure region, Microsoft’s guarantee you will have Virtual Machine Connectivity to at least one instance at least 99.99% of the time.
- For all Virtual Machines that have two or more instances deployed in the same Availability Set or in the same Dedicated Host Group, we guarantee you will have Virtual Machine Connectivity to at least one instance at least 99.95% of the time.
Read more on SLA for Virtual Machines
Q6. What happens if Microsoft doesn’t meet its SLA?
Ans. It is up to the customer or partner to determine if the Microsoft Azure service level agreement has not been met. In order to be eligible to submit a claim with respect to any incident, the customer must first have notified Customer Support of the incident within 5 business days following the incident.
The customer must also provide sufficient evidence to support the claim. Once the claim has been validated by Microsoft a credit of 10% will be awarded for SLA’s between 99.5% and 99%. For SLAs below 99%, a 25% credit will be issued for that particular month in which the SLA was not met.
Virtual Machine (VM) Extensions
Azure virtual machine (VM) extensions are small applications that provide post-deployment configuration and automation tasks on Azure VMs. The Azure platform hosts many extensions covering VM configuration, monitoring, security, and utility applications. Publishers take an application, wrap it into an extension, and simplify the installation.
For example, if a virtual machine requires software installation, anti-virus protection, or to run a script inside of it, a VM extension can be used.
Read more on Virtual Machines Extensions
Q7. How can we install an extension?
Ans. Azure VM extensions can be managed using the Azure CLI, PowerShell, Resource Manager templates, and the Azure portal. To try an extension, go to the Azure portal, select the Custom Script Extension, then pass in a command or script to run the extension.
Read more on Windows Custom Script Extension and Linux Custom Script Extension.
Q8. How can I find what extensions are available?
Ans. You can view available extensions by selecting a VM, then selecting Extensions in the left menu.
To pull a full list of extensions, see Discovering VM Extensions for Linux and Discovering VM Extensions for Windows.
Virtual Machines Scale Sets
Azure virtual machine scale sets let you create and manage a group of load-balanced VMs. The number of VM instances can automatically increase or decrease in response to demand or a defined schedule.
Scale sets provide high availability to your applications and allow you to centrally manage, configure, and update a large number of VMs. With virtual machine scale sets, you can build large-scale services for areas such as compute, big data, and container workloads.
Q9. How many VMs can I have in a scale set?
Ans. A scale set can have 0 to 1,000 VMs based on platform images, or 0 to 600 VMs based on custom images.
Q10. Can we create a scale set in an existing resource group and move a scale set to another resource group?
Ans. Yes, you can create a scale set in an existing resource group, and also you can move scale set resources to a new subscription or resource group.
Q11. Which Azure regions support scale sets?
Ans. All Azure regions support scale sets. To protect your virtual machine scale sets from data centre-level failures, you can create a scale set across Availability Zones. Azure regions that support Availability Zones have a minimum of three separate zones, each with its own independent power source, network, and cooling.
Azure Snapshot
An Azure Snapshot is a read-only copy of the existing disk in the Microsoft Azure Cloud. We can create a snapshot of the OS or Data disk. This snapshot can be used as a backup. The snapshot can also be used to create a Virtual Machine.
To create a Virtual Machine using a snapshot, it is better to shut down the VM before taking its snapshot.
We can create a full snapshot or an incremental snapshot.
- Full Snapshot: It makes a complete read-only copy of the selected disk.
- Incremental Snapshot: It saves on storage costs by making a partial copy based on the difference between the last snapshot. This does not make the complete copy of the existing disk each time.
Windows VM vs Linux VM
Windows has the Volume Snapshot Service (VSS) framework to ensure application consistent VM backup, but there is no such generic framework for Linux. To ensure your Linux VMs are application-consistent, you can use the Linux pre-script and post-script framework to take application-consistent backups.
Q12. How many snapshots can a VM have?
Ans. If the base disks are deleted, the snapshot files are not sufficient to restore a virtual machine. A maximum of 32 snapshots is supported in a chain. However, for better performance use only 2 to 3 snapshots. Do not use a single snapshot for more than 72 hours.
Q13. What is the VM snapshot size in azure?
Ans. The first incremental snapshot is billed only for the used size of 100 GB. 20 GB of data is added to the disk before you created the second snapshot. Now, the second incremental snapshot is billed for only 20 GB.
Q14. What disk types support snapshots?
Ans. Premium SSD, standard SSD, and standard HDD support snapshots. For these three disk types, snapshots are supported for all disk sizes (including disks up to 32 TB in size). Ultra disks do not support snapshots.
Quiz Time (Sample Exam Questions)!
With our Microsoft Azure Administrator training program, we cover 150+ sample exam questions to help you prepare for the certification AZ-104.
Check out one of the questions and see if you can crack this…
Ques: Can we create VM in Azure using CLI?
A. True
B. False
The right answer will be revealed in my next week’s email.
Here is the answer to the question shared last week (Scroll down at the end of this post for the question).
Ques: How many virtual machines can be deployed into a cloud service?
A. Unlimited
B. 25
C. 50
D. 1
Answer: C
Each cloud service can contain up to 50 virtual machines.
Related/References
- Create and Connect an Ubuntu Virtual Machine in Azure
- Availability options for Azure Virtual Machines
- SLA for Virtual Machines
- Virtual machines extensions and features for Windows
- Virtual Machines Scale Sets (VMSS) in Microsoft Azure
- [Recap] Day 1: Azure Administration & Governance and Compliance [Azure Administrator] [AZ-104]
- [Recap] Day 2: Azure Virtual Networking [Azure Administrator] [AZ-104]
- [Recap] Day 3: Azure Intersite Connectivity [Azure Administrator] [AZ-104]
- [Recap] Day 4: Azure Network Traffic Management [Azure Administrator] [AZ-104]
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