We have a service with low SLA requirements, so we host it on a single VM, no need for multiple VMs in availability set/zones.
What happens if there is a zone or fault domain failure?
Will Azure automatically reallocate the VM to an operational zone / host (FD), or we have to actively restart or redeploy the VM in order to reallocate it?
From the document, when facing an unexpected Downtime, Azure will migrate your VM to a healthy physical machine in the same datacenter.
When detected, the Azure platform automatically migrates (heals) your
virtual machine to a healthy physical machine in the same datacenter.
During the healing procedure, virtual machines experience downtime
(reboot) and in some cases loss of the temporary drive. The attached
OS and data disks are always preserved.
However, if you are using a single VM, it's recommended to use Standard SSD wither higher SLA.
A single instance virtual machine with a Standard SSD will have an SLA
of at least 99.5%, while a single instance virtual machine with a
Standard HDD will have an SLA of at least 95%. See SLA for Virtual
Machines.
Related
I have a VM that runs IIS and SQL server for an enterprise application used by around 100 users.
Right now I just have this VM but I would like to add some availability. It’s not critical to have zero downtime application but at least that if by some reason the server fails then I’m able to wake up a secondary instance and reroute traffic to it.
So I guess this is done by using Availabilty Sets but what I understand is that I have at least to have two VMs in the availability set and load balancer so traffic is redirected round robin to each VM. By using the above approach that means that I must have to pay for having two instances with same specs I guess.
What I would like and don’t know if this is possible is like having same above scenario where one the of the VMs is stopped so I don’t get any charge and in case of VM failure I can started maybe manually so the application works again. If this is possible how does the hard drive is available so that the other VM always have the latest data.
If it’s not possible then can I have then for the availabilty set a second VM with the lowest specs that my app can support so if the main VM fails at least critical users can still access the app (maybe performance won’t be great but app will work) and when main VM is functional again then main traffic is again redirected to main VM.
you can achieve this by having 2 vms with premium disks only and having one as a cold backup. single vm qualify for an SLA if they only use premium disks, SLA would be 99.9% afair.
with AV sets - you need to have at least 2 running vms.
I have purchased 1 year termed Windows Virtual Machine, and money is taken from my card.
The resource is created successfully. Check the image below.
But when i want to start the machine, i don't see any Power On, or whatever button which says to start the virtual machine.
What am i missing here?
After you buy an Azure Reserved Virtual Machine Instance, the reservation discount is automatically applied to virtual machines that match the attributes and quantity of the reservation. A reservation covers the compute costs of your virtual machines.
You can deploy Virtual machines that matches the reservation attributes and the hardware portion of the VM will be covered.
Here is the document to Manage reservations for Azure resources
After making an Azure Reserved VM Instance purchase, how do I know which VM got the Azure Reserved VM Instance discount?
https://learn.microsoft.com/en-us/rest/api/billing/enterprise/billing-enterprise-api-reserved-instance-usage
I happen to read this about ACL
"traffic from remote IP addresses is filtered by the host node instead of on your VM. This prevents your VM from spending the precious CPU cycles"
since VM's CPU cycles are saved by node, where does node reside?
Isn't node another name for VM?
Doesn't node reside inside VM?
About ACL, it's the classic model on Azure and now the Azure Resource Manager model is more recommended.
The host node means the physical server which supports the VM running on it. The traffic to the VM will come in from the Internet through the network interface of the host node. When you create the VM, there is a location would be chosen and that's the region where the host node in.
I have a huge problem in a production VM I was hosting on Azure infrastructure (size, in case it matters is: Standard DS14 (16 Cores, 112 GB memory))
The entire production server has gone offline, stopped reporting to New Relic, and I can't SSH into it either (it times out). I tried restarting the machine from the portal, but got the message:
The operation '7922f9ed80af7b2c9a9ec5d13f510393' failed: 'The operation cannot be performed because the virtual machine is faulted.'.
What can I do? This is quite a bind!
p.s. https://azure.microsoft.com/en-us/status/ shows all is well
Your issue happens on VM's host has fault.
Restart or create a new VM could solve this issue. Resizing the VM moves the VM to a different host server, so if there is an issue with the host that is impacting a VM, resizing it will get it off that host.
You could check whether your VMs in an availability set. An availability set is a group of virtual machines that are deployed across fault domains and update domains. An availability set makes sure that your application is not affected by single points of failure, like the network switch or the power unit of a rack of servers.
Let's say I have VM1 and VM2, using the service WS.cloudapp.com. Let's say I have an web app that has been depployed in both VM1 and VM2 in port 80. Because I'm not yet set up load balancing, so, for the port 80, only one VM can own, let's say VM1. When VM1 is down, end users also can not connect to WS.cloudapp.com. That lead to configuration high availability set is useless, isn't it?
You are correct. If you didn't setup LB endpoints the second VM will never receive requests. The ONLY purpose of availability set is to guarantee that at least 50% of your VMs in the same set will be provisioned in different physical hardware racks to avoid planned (or unplanned) maintenance events to affect all your VMs at the same time.
Availability Set must be combined with Load Balancer to guarantee 99.95% SLA . Combining the Azure Load Balancer (or any customized failover solution) with an Availability Set will guarantee the most application resiliency. One rules where the VMs will be provisioned physically and the other rules which VMs will receive public traffic.
There's also a problem you should be aware of that i quoted below:
Avoid single instance virtual machines in Availability Sets
Avoid leaving a single instance virtual machine in an Availability Set
by itself. Virtual machines in this configuration do not qualify for a
SLA guarantee and will face downtime during Azure planned maintenance
events. Also, if you deploy a single virtual machine instance within
an Availability Set, you will receive no advanced warning or
notification of platform maintenance. In this configuration, your
single virtual machine instance can and will be rebooted with no
advanced warning when platform maintenance occurs.
https://azure.microsoft.com/en-us/documentation/articles/virtual-machines-manage-availability/
If by "high availability set" you meant "availability set" then yes, you would not be getting the benefits from placing the VMs inside the set.
Though it's also probably worth noting that even if you place VMs in a set, failover is not instant.