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Failover between Primary and Secondary, then switch back when Primary is available RRS feed

  • Question

  • Azure Storage support the Geo-Redundancy by default. When the primary storage fails, it'll failover to the secondary storage.

    My question is whether I can let it switch back to the Primary storage when the primary is back online? Our main concern is the latency between secondary storage and the compute role since after the failover, they probably are not in the same DCs.

    Anyone can help?

    Wednesday, October 15, 2014 10:37 PM

Answers

  • Hi Barry,

    In the event of a major disaster that affects the Primary Storage location, we will first try to restore the Primary location. Dependent upon the nature of the disaster and its impacts, in some very rare occasions, we may not be able to restore the Primary location, and we would need to perform a geo-failover.

    When this happens, affected customers will be notified via their subscription contact information OR via Portal. As part of the failover, the customer’s “account.service.core.windows.net” DNS entry would be updated to point from the primary location to the secondary location. Once this DNS change is propagated, the existing Blob and Table URIs will work. This means that you do not need to change your application’s URIs – all existing URIs will work the same before and after a geo-failover.

    After the failover occurs, the location that is accepting traffic is considered the new primary location for the storage account. This location will remain as the primary location unless another geo-failover was to occur. Once the new primary is up and accepting traffic, we will bootstrap a new secondary, which will also be in the same region, for the failed over storage accounts. In the future we plan to support the ability for customers to choose their secondary location (when we have more than two data centers in a given region), as well as the ability to swap their primary and secondary locations for a storage account.

    You may refer the following link to know the Primary & their Secondary Storage account location:

    http://msdn.microsoft.com/en-us/library/azure/dn727290.aspx

    Regards,

    Manu Rekhar

    Thursday, October 16, 2014 4:46 AM
  • Surely, we will consider your feedback. Thank you

    And also, only in event of a major disasters like Earthquake or others wherein the entire Data Center is completely taken down and if we are unable to recover the primary storage datacenter, only then we will move the Storage account to Secondary data centers, which is very very rare case to happen.

    Regards,
    Manu Rekhar

    Sunday, October 19, 2014 3:47 AM

All replies

  • Hi Barry,

    In the event of a major disaster that affects the Primary Storage location, we will first try to restore the Primary location. Dependent upon the nature of the disaster and its impacts, in some very rare occasions, we may not be able to restore the Primary location, and we would need to perform a geo-failover.

    When this happens, affected customers will be notified via their subscription contact information OR via Portal. As part of the failover, the customer’s “account.service.core.windows.net” DNS entry would be updated to point from the primary location to the secondary location. Once this DNS change is propagated, the existing Blob and Table URIs will work. This means that you do not need to change your application’s URIs – all existing URIs will work the same before and after a geo-failover.

    After the failover occurs, the location that is accepting traffic is considered the new primary location for the storage account. This location will remain as the primary location unless another geo-failover was to occur. Once the new primary is up and accepting traffic, we will bootstrap a new secondary, which will also be in the same region, for the failed over storage accounts. In the future we plan to support the ability for customers to choose their secondary location (when we have more than two data centers in a given region), as well as the ability to swap their primary and secondary locations for a storage account.

    You may refer the following link to know the Primary & their Secondary Storage account location:

    http://msdn.microsoft.com/en-us/library/azure/dn727290.aspx

    Regards,

    Manu Rekhar

    Thursday, October 16, 2014 4:46 AM
  • Thanks for your reply!

    If I understand it correctly, the answer to my question is NO.

    There's no way for me to switch my primary storage to original one even when the original one is back online. Will your guys consider to add this support since if my compute role is in USNC while my storage is in USSC, it'll increase the latency. For example, if for a request which need to read/write data to storage for 4 times(read metadata, update metadata, read data, write data), it'll add 100+ms extra latency. (I searched online, the it said the latency between different data center should be within 45ms.)


    Shi Bai

    Thursday, October 16, 2014 7:31 PM
  • Surely, we will consider your feedback. Thank you

    And also, only in event of a major disasters like Earthquake or others wherein the entire Data Center is completely taken down and if we are unable to recover the primary storage datacenter, only then we will move the Storage account to Secondary data centers, which is very very rare case to happen.

    Regards,
    Manu Rekhar

    Sunday, October 19, 2014 3:47 AM