Accessibility of Web role instances

Question

Hi!

Question 1.

Assume I have the only one Web role in a service. I change the number of instances from 1 to 2. While creating the second Web role, the first is in the state "Updating". If one makes a request to the URL <dns-prefix>.cloudapp.net, there is no answer! Why? Is the instance blocked while updating?

Question 2.

I have one Web role and I reboot it (the button "Reboot" on the portal). The execution of the method "OnStart" is not yet finished, but I get a responce from URL <dns-prefix>.cloudapp.net. I thought that the Load balancer sends requests if only a role is in the state "Ready".
The similar problem. I reboot 1 of 3 Web roles and it is in the state "Stopping". For some seconds I get no responce from <dns-prefix>.cloudapp.net (Connection timeout).

P.S. I know that I should have at least 2 instances for each role. But suppose I want to have 1 for cost saving and testing purposes.

Answer 1

Hello.

Maybe i'm wrong, but i think, that when amount of instances increases, role re-reads its configuration file and it's logical that it can't answer to requests - because in the same time there is a process of load balancers configuration. But it is only an assumption. The same assumption about your second question. 

Answer 2

Hi Sergey,

I am experiencing the same behaviour from Windows Azure last days. I am presenting a detailed description in another thread http://social.msdn.microsoft.com/Forums/en-US/windowsazuretroubleshooting/thread/3fcadf60-f14b-41a3-adf7-b24bc79a3f51.

I believe that this is a bug of the system. I can confirm this was not happening some days ago.

Answer 3

Hi Dimitris,

Thank you for this information. I think it's better to wait for the fix, and then to try the same actions.

One of the important things which I want to understand: how quickly Load Balancer understands that role is rebooting (for example, when I press "Reboot" on the portal). Does Load Balancer understand it immediately or does it continue to send requests to this instance for some seconds?

Answer 4

Alexander,

Thank you for your answer!

In Dimitris' theme Robbin Cremers wrote the same thing:

"When you change your instance count from 1 to 2, you basically redeploy a new configuration file, which will result in a reboot of the instance. The configuration file can contain multiple changes, so it has to be reloaded to make sure all changes to the configuration file are picked up.

Since you only have 1 instance, it will go down while being upgraded."