I have a App service hosted in Windows Azure in a region. When there are some issues with Azure servers in the hosted region, the app service goes down and the users are unable to see the website.
I would like to know if there is a way to geo-replicate the app service so that if the servers are down in 1 region, the website should automatically redirect it to a different server?
You can geo-replicate your app service by using Azure Traffic Manager service, which allows you to control the distribution of user traffic to your service endpoints running in different datacenters around the world.
As of today, Azure Traffic Manager provides 3 ways for routing the traffic: Priority, Weighted and Performance. For what you're looking to accomplish, I believe you would want to choose Priority routing method.
To learn more about how you can make use of this service to make your app service highly available, please see this link: https://azure.microsoft.com/en-us/documentation/articles/app-service-app-service-environment-geo-distributed-scale/.
This is an old entry but I thought I'd chime in after working with Azure for a few years.
If your statement "When there are some issues with Azure servers in the hosted region" is referring to transient outages, what you might be experiencing is your App Service Plan instance transitioning. Microsoft regularly moves ASP instances to new machines for reasons that make sense to them. Likely this is to load balance hardware or apply patches to the underlying VMs that host app services.
It has been my experience that when the ASP instances are moved, the new ASP instance needs time to warmup the app services hosted on it. If your ASP is configured with only 1 instance, your app service will be unreachable during this time.
If on the other hand, you configure your ASP with a minimum of 2 instances, Microsoft will synchronize the moving of the instances so that at least 1 remains up and available while the other is being moved.
Of course running a multi instance ASP requires your application to either be stateless or built using a session provider other than the default .Net "In Memory" session provider. CosmosDB for instance.
Related
I was previously running both my wordpress application and the mysql database server installation inside the same Linux Virtual Machine on Azure. I recently migrated both to Azure App Service and Azure Database for MySQL Flexible Server respectively in the same region - East US. Unfortunately, this has really slowed down the application and page load times have increased to an average of 11 s from 1 s. I served all static files from a CDN but to no avail. Checking the network waterfall, the scripts blocking the page are calls to admin-ajax.php. Increasing the compute of both services to a ridiculous size (there is no traffic right now) only improves the speed to 6 s. Since, both services are in the same region I do not believe there can be such a significant network latency between the server and db. What additional steps can I take to troubleshoot the issue?
If you isolate the slowness endpoints and if its due to SQL then I suggest to configure VNET integration with app service and use service endpoint, Microsoft.SQL at subnet of app service integrated subnet such that some of limitation regarding number of sockets and network latency rule out and should observe performance gain. Parallelly you need to check SQL execution time either using profiling of queries or using Performance recommendations.
I have seen variations of this question but couldn't find any that dealt with our particular scenario.
We have an existing aps.net website that links to a SQL Server database.
The database has clr user-defined types, hence it can only be hosted in Azure VM since Cloud Services don't support said types.
We initially wanted to use a vm for the database and cloud service for the front-end, but then some issues arose:
We use StateServer for storing State, but Azure doesn't support that. We would need to configure either Table storage, SQL Databases, or a Worker role dedicated to State management (a new worker role is an added cost). Table storage wouldn't be ideal due to performance. The other 2 options are preferable but they introduce cost or app-reconfiguration disadvantages.
We use SimpleMembership for user management. We would need to migrate the membership tables from our vm instance sql server to Azure's SQL Databases. This is an inconvenience as we want to keep all our tables in the same database, and splitting up the 2 may require making some code changes.
We are looking for a quick solution to have this app live as soon as possible, and at manageable cost. We are desperately trying to avoid re-factoring our code just to accommodate hosting part of the app in Azure Cloud services.
Questions:
Should we just go the VM route for hosting everything?
Is there any cost benefit in leveraging a VM instance (for sql server) and a Cloud Service instance (for the front-end)?
It seems to me every added "background process" to a Cloud Service will require a new worker role. For example, if we wanted to enable smtp for email services, this would require a new role, and hence more cost. Is this correct?
To run SQL Server with CLR etc, you'll need to run SQL Server in a Virtual Machine.
For the web tier, there are advantages to Cloud Services (web roles), as they are stateless - very easy to scale out/in without worrying about OS setup. And app setup is done through startup scripts upon bootup. If you can host your session content appropriately, the stateless model will be simpler to scale and maintain. However: If you have any type of complex installations to perform that take a while (or manual intervention), then a Virtual Machine may indeed be the better route, since you can build the VM out, and then create a master image from that VM. You'll still have OS and app maintenance issues to contend with, just as you would in an on-premises environment.
Let me correct you on your 3rd bullet regarding background processes. A cloud service's web role (or worker role) instances are merely Windows Server VM's with some scaffolding code for startup and process monitoring. You don't need a separate role for each. Feel free to run your entire app on a single web role and scale out; you'll just be scaling at a very coarse-grain level.
Some things to consider...
If you want to be cheap, you can have your web/worker role share the same code on a single machine by adding the RoleEntryPoint. Here is a post that actually shows how to do what you are trying to do with sending email:
http://blog.maartenballiauw.be/post/2012/11/12/Sending-e-mail-from-Windows-Azure.aspx
Session management is painfully slow in SQL Azure DB, I would use the Azure Cache if you can..it is fast.
SQL Server with VMs is going to cause problems for you, because you will also need to create a virtual network between that and any cloud services. This is really stupid, but if you deploy a cloud service AND a VM they communicate over the PUBLIC LOAD BALANCER causing a potential security concern and network latency. So, first you need to virtual network them (that is an extra cost)..then you also need to host a DNS server to address the SQL Server VM. Yes this is really stupid, unless you are OK with your web/worker roles communicating with your SQL Server over the internet :)
EDIT: changed "public internet" to "public load balancer" (and noted latency)
EDIT: The above information is 100% correct contrary to the comment by David below. Please read the guidance from Microsoft here:
http://msdn.microsoft.com/library/windowsazure/dn133152.aspx#scenario
DIRECTLY FROM MICROSOFT GUIDANCE speaking about cross Cloud Service communication (VM->web/worker roles):
"We recommend that you implement the first option as the connection process would not need to go through the public Internet. Therefore, it would provide a better network performance."
As of today (8/29/2013) Azure VMs and Worker/Web Roles are deployed into DIFFERENT "Cloud Services". Therefore communication between them needs to be secured via a Virtual Network that exposes private IP addresses between the instances.
To follow up on David's point below, that about adding an ACL. You are still sending packets over the internet using TDS (SQL Server protocol). That can be encrypted, but no sane architect/enterprise governance/security governance would "allow" this scenario to happen in a production environment.
My website is running quite well and serving lacks of pages on daily basis. We want to add one more web server to share load on server at heavy traffic times. Instead, can I go with Amazon Elastic Compute Cloud (EC2) or any other cloud service as an alternative solution.
In cloud server environment, need I to install multiple instances as traffic increases or a single instance can scale based on the traffic?
I would suggest Windows Azure
You're right in that you would have multiple instances that scale to meet traffic. With the Azure platform you would design your application into Roles (chunks of functionality), where they make sense to create multiples of, like a page that displays store contents should be highly scalable, whereas the login portion may not. Windows Azure already runs services for Microsoft like Xbox Live and their BPOS offerings, plus there are great tools to develop for the Azure Cloud. You can read more about cloud development at MSDN.
We have two servers, both are containing a local application connecting to local web service, applications and services are identical on both servers.
One of the servers work just fine,
The other one is just dead, I have impression the the security configuration are different on those servers.
What prevents an application X from connecting a web-service, given that another application y on the same server can connect to it. and X is a windows service.
What I should check, what is chances?
Thanks
Check if there is any firewall that might need to some ports opened up.
Could there be any kind of AntiVirus or similar set up on one of the servers?
Basic troubleshooting of loosely-coupled applications means independent testing/verification of those services.
Can you access the web service locally through a different application, i.e. a web browser? If you can't reach the service through the browser, then the server configurations (at some level) are not identical.
Only after you're certain the service is reachable should you look into issues with the windows service.
I have a situation very similar to the one in this question:
Selective Cache clearing across load balanced servers (ASP.Net)
The difference is that due to our hosting configuration, I am unable to address individual servers by IP address. Assuming I cannot access specific servers via web requests, is it possible to access the HttpContext of a web application running on the same machine? I'm thinking I could accomplish this with a windows service that I could address by machine name, or alternately a console application, I just don't know if I can gain access to the web application cache either way.
You can expose content of the WebCache of an app through some Remoting/WCF code built into the web app. I hope you can use localhost to access it from an app on the same box.