Windows Azure Storage (+) Azure Storage Read access Geo redundancy (read Access–geo redundant Storage, Ra-grs)

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Careful users will find that Microsoft is paired with data center construction both abroad and domestically, such as the Hong Kong Data Centre (Asia East) and the Singapore Data Centre (South East Asia). This is because Microsoft fully considers the ability of geo-redundancy. Between the two data centers, such as Hong Kong and Singapore, there will be a dedicated line connection, which is used for data synchronization before the intranet data center.

In general, the correspondence between the primary and standby nodes is as follows:

　　

Primary	Secondary
North Central US	South Central US
South Central US	North Central US
East US	West US
West US	East US
North Europe	West Europe
West Europe	North Europe
South East Asia	East Asia
East Asia	South East Asia

Now, Microsoft provides read access to geo-redundancy (read Access-geo redundant Storage, Ra-grs).

Simply put, if the user creates a storage account in the Hong Kong Data Center (primary location) , and the Ra-grs is turned on, the transaction is replicated asynchronously to the Singapore Datacenter (secondary location). Ra-grs provides read-only access to the data center (secondary location) replicated to Singapore for higher read availability to the storage account.

This allows users to specify that access to azure storage points to the Hong Kong Datacenter (primary location)or to the Singapore Data Center (secondary location)for high availability of read.

In general, the primary location can be accessed through myaccount.<service>.core.windows.net , via myaccount-Secondary . <service>.core.windows.net to access the secondary location

For example, let's say I created Azure Storage,storage name LEIVM in the Hong Kong Data Center (primary location) , and Read access geo-redundancy was turned on (read Access–geo Redundant Storage, Ra-grs).

1. I can access data from the Hong Kong Data Centre (primary location) via https://leivm.blob.core.windows.net/

　　2. You can then access the Azure Storage account at the secondary location via https://leivm-secondary.blob.core.windows.net/.

Next, start the chapter.

1. First we create a new storage account named Leireadaccess,affinity Group to select the Hong Kong data center. Please note that replication selects Read-access geo-redundant. Such as:

　　

　　In this way, the Hong Kong Data Centre is the primary location and the Singapore Data Centre is a secondary location.

2. Once created, we create the container, the name is set to photos, and the property is set to the public blob

　　

3. After the creation, we will upload a local image msft.png to photos.

Then the URL access address of this PNG image is http://leireadaccess.blob.core.windows.net/photos/msft.png, so that you can display access to the image saved in the Hong Kong data center.

After a moment, this image will be saved asynchronously to the Singapore Data Centre via a dedicated line between the Hong Kong Data Centre and the Singapore Data Centre.

We can access a copy of this image in the Singapore Data Centre via Http://leireadaccess-secondary.blob.core.windows.net/photos/msft.png. Such as:

　　

This way, if the data center in Hong Kong is inaccessible due to anomalies, we can access the data in the cloud by accessing the secondary data center. This allows for higher read availability to the storage account.

　　

　From my experience and official Microsoft documentation, the RPO between two data centers is up to 15 minutes in duration .

Interested readers can refer to the documentation

http://blogs.msdn.com/b/windowsazurestorage/archive/2013/12/04/ Introducing-read-access-geo-replicated-storage-ra-grs-for-windows-azure-storage.aspx