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RA-GRS - mount vhd RRS feed

  • Question

  • Hi,

    Using Read Access Geo Replicated Storage allows me to mount a VHD on a vm on the secondary region to where the data is being replicated, just to prove a customer that all data is really present on the disk in case a recovery would in fact be needed?

    Thank you,

    Thursday, October 23, 2014 10:47 AM

Answers

  • Geo-replication specifically in regards to disaster recovery.  The distributed and replicated file system (DFS) layer is responsible for storing bits on disk.  It will not report success until the bits are stored across the multiple DFS servers.  This process is described in the Windows Azure Storage Architecture Overview.  Currently geo-replication is for failover of a data center.  In the event of a major disaster that affects the primary location, we will first try to restore the primary location. Dependent upon the nature of the disaster and its impacts, in some rare occasions, we may not be able to restore the primary location, and we would need to perform a geo-failover.  Data is replicated asynchronously.  Write order is guaranteed within a VHD. It is not guaranteed across VHDs.

    Coming to your question, there is no way as of today that you can access vhd in secondary storage. Only at the time of complete disaster that affects the primary location, we will first try to restore the primary location onto secondary storage will come into picture.

    Let me know if this answers your question.

    Tuesday, October 28, 2014 12:36 AM

All replies

  • Hi,

    Please refer this link which talks about Geo-replication for Windows Azure Storage:

    http://blogs.msdn.com/b/windowsazurestorage/archive/2011/09/15/introducing-geo-replication-for-windows-azure-storage.aspx

    Let us know if it helps.

    Regards,
    Azam khan

    Thursday, October 23, 2014 12:46 PM
  • Hi,

    Thank you for your answer, but this does not clarifies my question.

    Please read carefully what cenario I need to see if this is possible. If you have any doubts on what I really need to do (in case I did not explain myself correctly on my question above), please advise and I will try to reformulate the question.

    Thank you.

    Thursday, October 23, 2014 3:26 PM
  • Hi,

    Yes Read-access geo-redundant storage (RA-GRS) allows read access to data at the secondary region in the event that the primary region becomes unavailable. Read-access geo-redundant storage is recommended for maximum availability in addition to durability.

    For more information, refer this link:
    http://azure.microsoft.com/en-us/documentation/articles/storage-manage-storage-account/

    Regards,
    Azam Khan

    Friday, October 24, 2014 11:24 AM
  • I know Read Access geo redundant storage allows read access to data... But I cannot find anywhere a way to mount a VHD from that secondary region on a vm running also on that secondary region.

    Has anyone done this?

    I need this to prove our customer that vhd is consistent and has up to date data. This is for auditing purposes...

    Saturday, October 25, 2014 9:50 PM
  • Hi,

    I would request you to refer this link which talks clearly about windows azure storage redundancy options and read access geo redundant storage:

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

    Regards,
    Azam Khan

    Monday, October 27, 2014 3:46 AM
  • Well, I would sure hope if there was someone capable of answering my question. I had already seen all those links before posting my question here.

    Neither of the information I got so far answers my question. I only see links and posts on how to read block blobs... I want to be able to mount a page blob VHD on a virtual machine from the RA-GRS storage.

    There is absolutelly no information about if it is even possible to do this... and for the answers I got here so far, it really seems no one knows if this is possible...

    Monday, October 27, 2014 9:46 AM
  • Geo-replication specifically in regards to disaster recovery.  The distributed and replicated file system (DFS) layer is responsible for storing bits on disk.  It will not report success until the bits are stored across the multiple DFS servers.  This process is described in the Windows Azure Storage Architecture Overview.  Currently geo-replication is for failover of a data center.  In the event of a major disaster that affects the primary location, we will first try to restore the primary location. Dependent upon the nature of the disaster and its impacts, in some rare occasions, we may not be able to restore the primary location, and we would need to perform a geo-failover.  Data is replicated asynchronously.  Write order is guaranteed within a VHD. It is not guaranteed across VHDs.

    Coming to your question, there is no way as of today that you can access vhd in secondary storage. Only at the time of complete disaster that affects the primary location, we will first try to restore the primary location onto secondary storage will come into picture.

    Let me know if this answers your question.

    Tuesday, October 28, 2014 12:36 AM