Explore Windows Azure failover mode and high-availability modes!

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Now there are a lot of domestic users of the availability of cloud services misunderstanding, what kind of misunderstanding? For example, a cloud service provider, there is a room in South China, there is a computer room in east China.

The customer mentions a requirement, what do you mean by the concept of 99% usability? Is there something wrong with my machine in the Southern engine room? My machine on its own initiative to transfer to East China computer room?

From the moment of communication and communication with customers, it seems that most users have this idea. Think that cloud services should be highly available from cross-regional and cross-site directions, but this is a very difficult goal to achieve.

In the financial industry, the concept of the three centres of the two places often exists, in the concept of the three centres. We can often see descriptive narratives such as the following definitions:

Primary Data Center

The entire business and data hosting center, in order to ensure more reliable data access and high availability. Generally speaking, the data center is within one kilometer of our office space.

All data, database, Access layer applications are hosted in the data center

Secondary data Center

The business of the secondary datacenter is the equivalent of a copy of all the primary hosting data centers. To ensure the overall security of our data, our data centers are about a few kilometres from Our main data center, preventing small-scale disasters like fire and flooding in the main data center.

Secondary data centers perform data switching after similar small-scale disasters in the primary data center. Most businesses use the secondary data center as a fallback site, and many businesses use the same city's secondary data center as their backup site.

When an alternate site is enabled, most users of the enterprise's Business data center can take advantage of the office facilities in the secondary datacenter.

Secondary data centers in the third place

Usually the data center of the third place is the same city as the data center due to the large-scale scourge caused by the inability to resume business in the short term. Then you must enable the third-place data center to start the business. Ensure the continuous execution of the business. Usually offsite data center recovery needs to do some network, business and data switching time, so the third place to switch the data center needs 4 hours or so, after the switch, the key business personnel can be the way to work on the plane, to ensure that the key business data can be continuously implemented.

So most of the cases we mentioned in SLA 99% above in most cases are all local high availability conditions.

And based on the three-center model we are relatively investment is also very large, because it must be considered to achieve the corresponding level of SLA needs we have to invest the corresponding hardware and software costs, for the two places, to achieve the equivalent level of application, we have to ensure that at least our hardware investment is 2 times above. And when the third center is enabled. Our cost is also the corresponding hardware cost is at least 3 times or more than dozens of times times.

The high availability of most clouds today does not mean that higher availability SLA levels can be transferred across geographies, and in most cases high availability for on-premises applications, and remote high availability means that it is not implemented with a single-instance architecture.

Microsoft Cloud now has two different data centers in East China and north China. The 99.95% is now available in high availability. Of course, we must also design a highly available architecture to ensure that our data operations are normal.

There is a problem with the data and applications that have failed. How do we make sure the data is OK? That depends on one of our key Azure features :

Trafficmanager

Traffic Manager Chinese translation for flow control. This allows a very large number of people to feel that is the control of traffic size, in fact traffic Manger A very important function is to control our traffic trend.

Now traffic supports three traffic trend modes:

2. failover

   His work mode is to work by aliases, 2 cloud services or multiple cloud services to failover, the system built-in self-detection method can detect the corresponding site and folder whether the situation, in the event of a failure, He uses the mechanism of his own initiative to detect traffic directed to the normal website.

3. Based on performance

   To load-balance endpoints distributed across the world's different datacenters, you can direct incoming traffic to the closest endpoint, due to the lowest latency between the client making the request and the endpoint.

   Typically, the closest endpoint corresponds to an endpoint with the shortest geographic distance. You can use the performance load balancing method to distribute based on location and latency, but you cannot consider real-time changes in your network configuration or load.

   Traffic manager periodically generates the Span lang= "en-us" > "Internet delay table " . The Traffic manager infrastructure performs a test to determine the round-trip time between the global differences and the Azure Data center that hosts the endpoint.

5. Dnsrr

   This way, users are interviewed based on the weight of the app being interviewed, or the user's random access is implemented under the same weights, that is, the load of access based on the DNS Round Robin approach.

Our next goal is to implement the failover of application access. We then implemented the application and access load balancing based on the simple complexity of the application.

Our next sample session is a simple static page, based on SQL Azure and SQL virtual machines. There are also multi-site access and replication technologies for MySQL and mysql virtual machines that have multiple site synchronization to complete data.

Our next article will be configured as a simple way to operate and configure the failover model based on the different requirements after the subscription is received.

Explore Windows Azure failover mode and high-availability modes!