Create stretched cluster volumes Synchronous

Roger Jany 1 Reputation point
2020-09-17T13:21:34.12+00:00

Hello,

I can't find out whats the diffrence between Asynchronous or Synchronous Cluster Volumes.

i think Asynchronus only replicating to the other side but i can use is only on the Primary side.

If i setup an synchronous Volume is it Possible to access this Volume on both sides?

So i can run VM's on Site A and Site B simultaneously on the same Volume?

Are the Resiliency only on Site A or B or on both sites?

Best regards

Roger

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  1. Trent Helms - MSFT 2,381 Reputation points Microsoft Employee
    2020-09-17T20:06:04.327+00:00

    Hello Roger,

    The links below may help to answer your questions. In a nutshell, the difference is the frequency at which the volume is being replicated. Synchronous is continuous to ensure no data loss between the volume copies and used for high-bandwidth, low-latency links. Asynchronous replication allows more leniency at the risk of some data loss. However, it is better for higher-latency links so you still have an option to use Storage Replica.

    https://learn.microsoft.com/en-us/windows-server/storage/storage-replica/storage-replica-overview#synchronous-replication

    https://learn.microsoft.com/en-us/windows-server/storage/storage-replica/storage-replica-overview#asynchronous-replication

    Replication occurs in one direction and the destination should not be brought online to avoid corruption (except for testing with 'Test Failover')

    https://learn.microsoft.com/en-us/windows-server/storage/storage-replica/storage-replica-frequently-asked-questions#FAQ6

    If you want to run VMs on both sites and still wanted to use Storage Replica, you could set up a source volume at each site and have it replicate to the other.

    Best regards,
    Trent

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  2. Alex Bykovskyi 1,831 Reputation points
    2020-09-20T14:30:58.233+00:00

    Hey Roger,

    Just to add, the following guide contains most of the information on how to create stretched cluster.
    https://learn.microsoft.com/en-us/windows-server/storage/storage-replica/stretch-cluster-replication-using-shared-storage
    In addition, do not forget that synchronous replication and asynchronous replication have different networks requirements. For Synchronous replication, 1 GbE network connection with RTT less than 5ms is required.
    Alternatively, you can build stretch cluster using the following guide:
    https://www.starwindsoftware.com/resource-library/starwind-virtual-san-2-node-stretched-hyper-v-cluster-on-windows-server-2016/

    Cheers,

    Alex Bykovskyi

    StarWind Software

    Note: Posts are provided “AS IS” without warranty of any kind, either expressed or implied, including but not limited to the implied warranties of merchantability and/or fitness for a particular purpose.

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