Azure VM Availability SLA

This post is focusing on the availability SLA of Azure Virtual Machines. You might think that there is not so much to say about it, even so, the reality is different.
Let me ask you a simple question when you talk about availability and Azure Virtual Machines:

When do you have 99.9% availability?
When do you have 99.95% availability?

Case 1: Single VM
When there is only one instance of VM, the SLA guaranty us minimum 99.9% availability. There are no actions that you can take to improve this value. Remember that this is the minimum value that is guaranteed. This value means that the real value can be higher than 99.9%.

Case 2: Two or more VMs in the same Availability Set
When there are two or more VMs in the same Availability Set, you have the availability SLA to 99.95%. This value means that:

The availability of the two or more VMs combined is at least 99.95%.
On the other hand, this does not mean that for each VM the availability is 99.95%. Per node the availability can be lower but combined, you get 99.95%.

Case 3: Single VM inside a Scale Set
When you have only one VM in a Scale Set, the same SLA is offered as for a Single VM – 99.9%. Having a single, VM inside a VM does not offer additional VM availability.

Case 4: Two or more VMs on a Scale Set with at least Two Fault Domains
Having at least two VMs inside at least two fault domains guaranty us an availability SLA at 99.95%.

Things to consider
There is no increased availability offered if you have only one VM as a single VM or inside a Scale Set (99.9%). Inside a Scale Set, if you have two VMs inside the same Fault Domain the SLA for availability remains the same as for one VM (99.9%). It is required to have multiple VMs inside different Fault Domain or inside an Availability Set to get 99.95% availability.

Comments

Windows Docker Containers can make WIN32 API calls, use COM and ASP.NET WebForms

After the last post , I received two interesting questions related to Docker and Windows. People were interested if we do Win32 API calls from a Docker container and if there is support for COM. WIN32 Support To test calls to WIN32 API, let’s try to populate SYSTEM_INFO class. [StructLayout(LayoutKind.Sequential)] public struct SYSTEM_INFO { public uint dwOemId; public uint dwPageSize; public uint lpMinimumApplicationAddress; public uint lpMaximumApplicationAddress; public uint dwActiveProcessorMask; public uint dwNumberOfProcessors; public uint dwProcessorType; public uint dwAllocationGranularity; public uint dwProcessorLevel; public uint dwProcessorRevision; } ... [DllImport("kernel32")] static extern void GetSystemInfo(ref SYSTEM_INFO pSI); ... SYSTEM_INFO pSI = new SYSTEM_INFO(

Azure AD and AWS Cognito side-by-side

In the last few weeks, I was involved in multiple opportunities on Microsoft Azure and Amazon, where we had to analyse AWS Cognito, Azure AD and other solutions that are available on the market. I decided to consolidate in one post all features and differences that I identified for both of them that we should need to take into account. Take into account that Azure AD is an identity and access management services well integrated with Microsoft stack. In comparison, AWS Cognito is just a user sign-up, sign-in and access control and nothing more. The focus is not on the main features, is more on small things that can make a difference when you want to decide where we want to store and manage our users. This information might be useful in the future when we need to decide where we want to keep and manage our users. Feature Azure AD (B2C, B2C) AWS Cognito Access token lifetime Default 1h – the value is configurable 1h – cannot be modified

ADO.NET provider with invariant name 'System.Data.SqlClient' could not be loaded

Today blog post will be started with the following error when running DB tests on the CI machine: threw exception: System.InvalidOperationException: The Entity Framework provider type 'System.Data.Entity.SqlServer.SqlProviderServices, EntityFramework.SqlServer' registered in the application config file for the ADO.NET provider with invariant name 'System.Data.SqlClient' could not be loaded. Make sure that the assembly-qualified name is used and that the assembly is available to the running application. See http://go.microsoft.com/fwlink/?LinkId=260882 for more information. at System.Data.Entity.Infrastructure.DependencyResolution.ProviderServicesFactory.GetInstance(String providerTypeName, String providerInvariantName) This error happened only on the Continuous Integration machine. On the devs machines, everything has fine. The classic problem – on my machine it’s working. The CI has the following configuration: TeamCity .NET 4.51 EF 6.0.2 VS2013 It see

Cloud as a Story - Vunvulea Radu

Search This Blog