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Are SQL Server FCI with S2D supported between Availability Zones?

    Question

  • Can you build an Storage Spaces Direct (S2D) based cluster where each node is in a different Availability Zones? If so, can you post a link to the documentation?

    David A. Bermingham, MVP, Senior Technical Evangelist, SIOS Technology Corp

    Monday, September 17, 2018 7:12 PM

Answers

  • Matt,

    It is not supported as it hasn't been tested.  When you start getting into putting them in different zones, you are stretching the S2D.  The stretch scenario has not been tested and something we are not recommending doing.  Latency really isn't the reason.  Really, it all boils down to the Health Service and the Storage Bus Layer (SBL).  With the Health Service, it can only do one storage pool.  That storage pool would be spread across all the nodes.  Inside the pool are the storage spaces that contain the actual data.  Data is laid out with extents and extents are spread out between disks on the nodes.  The extents and placements are handled by SBL.  SBL must be able to talk between all the disks so it knows where to place everything.  Because of this, SBL needs to be able to communicate between all the nodes.  So SBL will be additional load on the network.  So latencies in a network could cause slower times writing and reading the various extents.   If there is a break between the zones, then you will not be able to see the data that is spread between them.

    This scenario is something we are looking at for the next version of Windows.


    Thanks, John Marlin Microsoft Program Manager

    Thursday, May 16, 2019 7:26 PM
  • Availability Zones are different physical locations.  Availability Sets are different hardware within the same location.  We are not supporting Storage Spaces Direct nodes being in separate Availability Zones at this time.  However, we do support them in different Availability Sets.

    Thanks, John Marlin Microsoft Program Manager

    Tuesday, September 18, 2018 7:39 PM

All replies

  • Availability Zones are different physical locations.  Availability Sets are different hardware within the same location.  We are not supporting Storage Spaces Direct nodes being in separate Availability Zones at this time.  However, we do support them in different Availability Sets.

    Thanks, John Marlin Microsoft Program Manager

    Tuesday, September 18, 2018 7:39 PM
  • Can you please elaborate on the following? "We are not supporting Storage Spaces Direct nodes being in separate Availability Zones at this time"?

    1. Are there are checks on the OS level to prevent the setup of the nodes in different AZs or it is simply not tested/validated and so is not recommended to try in a production setup? (for example with SQL Server Failover Cluster) 

    2. Are there plans to support this scenario in Windows 2019 during its 10-year support lifecycle or is it more likely to be considered in the next version of Windows/S2D?

    Wednesday, January 16, 2019 1:11 AM
  • John Marlin [MSFT - can I ask about this? Surely this will let you create 2 VMs in an Availability Zone and then you can create S2D on them?  So is the not supporting it just due to latency issues that may be experienced....so you can set it up but "its not supported if you have issues"?

    Thanks :-)

    Thursday, May 16, 2019 6:14 PM
  • Matt,

    It is not supported as it hasn't been tested.  When you start getting into putting them in different zones, you are stretching the S2D.  The stretch scenario has not been tested and something we are not recommending doing.  Latency really isn't the reason.  Really, it all boils down to the Health Service and the Storage Bus Layer (SBL).  With the Health Service, it can only do one storage pool.  That storage pool would be spread across all the nodes.  Inside the pool are the storage spaces that contain the actual data.  Data is laid out with extents and extents are spread out between disks on the nodes.  The extents and placements are handled by SBL.  SBL must be able to talk between all the disks so it knows where to place everything.  Because of this, SBL needs to be able to communicate between all the nodes.  So SBL will be additional load on the network.  So latencies in a network could cause slower times writing and reading the various extents.   If there is a break between the zones, then you will not be able to see the data that is spread between them.

    This scenario is something we are looking at for the next version of Windows.


    Thanks, John Marlin Microsoft Program Manager

    Thursday, May 16, 2019 7:26 PM
  • Thanks :-) I was curious more than anything so thats useful
    Thursday, May 16, 2019 7:28 PM