sql-server-linux-availability-group-cross-platform.md

title	Configure SQL Server Always On Availability Group on Windows and Linux | Microsoft Docs
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ms.date	01/31/2018
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Configure SQL Server Always On Availability Group on Windows and Linux (cross-platform)

[!INCLUDEtsql-appliesto-sslinux-only]

This article explains the steps to create an Always On Availability Group (AG) with one replica on a Windows server and the other replica on a Linux server. This configuration is cross-platform because the replicas are on different operating systems. Use this configuration for migration from one platform to the other or disaster recovery (DR). This configuration does not support high-availability because there is no cluster solution to manage a cross-platform configuration.

Before proceeding, you should be familiar with installation and configuration for SQL Server instances on Windows and Linux.

Scenario

In this scenario, two servers are on different operating systems. A Windows Server 2016 named WinSQLInstance hosts the primary replica. A Linux server named LinuxSQLInstance host the secondary replica.

Configure the Availability Group

The steps to create the AG are the same as the steps to create an AG for read-scale workloads. The AG cluster type is NONE, because there is no cluster manager.

1. Install SQL Server 2017 on Windows Server 2016 and enable Availability Groups from SQL Server Configuration Manager.

   

   SQL Server Configuration Manager notes that the computer is not a node in a failover cluster.

   After you enable Availability Groups, restart SQL Server.

2. Install SQL Server 2017 on Linux. Enable hadr via mssql-conf.

   To enable hadr via mssql-conf from a shell prompt, issue the following command:

   sudo /opt/mssql/bin/mssql-conf set hadr.hadrenabled 1

   After you enable hadr, restart the SQL Server instance.

   The following image shows this complete step.

   

3. Configure hosts file on both servers or register the server names with DNS.

4. Open up firewall ports for TPC 1433 and 5022 on both Windows and Linux.

5. Create a database for the AG. The example steps use a database named <TestDB>.

   [!NOTE] For the scripts in this article, angle brackets < and > identify values that you need to replace for your environment. The angle brackets themselves are not required for the scripts.

6. Take a full backup of the database.

7. On the primary replica, create a database login and password.

   CREATE LOGIN dbm_login WITH PASSWORD = '<C0m9L3xP@55w0rd!>';
   CREATE USER dbm_user FOR LOGIN dbm_login;
   GO

8. On the primary replica, create master key, certificate, and backup the certificate.

   CREATE MASTER KEY ENCRYPTION BY PASSWORD = '<C0m9L3xP@55w0rd!>';
   CREATE CERTIFICATE dbm_certificate WITH SUBJECT = 'dbm';
   BACKUP CERTIFICATE dbm_certificate
   TO FILE = 'C:\Program Files\Microsoft SQL Server\MSSQL14.MSSQLSERVER\MSSQL\DATA\dbm_certificate.cer'
   WITH PRIVATE KEY (
           FILE = 'C:\Program Files\Microsoft SQL Server\MSSQL14.MSSQLSERVER\MSSQL\DATA\dbm_certificate.pvk',
           ENCRYPTION BY PASSWORD = '<C0m9L3xP@55w0rd!>'
       );
   GO

9. Copy the certificate and private key to the Linux server (secondary replica) at /var/opt/mssql/data. You can use pscp to copy the files to the Linux server.

10. Set the group and ownership of the private key and the certificate to mssql:mssql.

    The following script sets the group and ownership of the files.

    sudo chown mssql:mssql /var/opt/mssql/data/dbm_certificate.pvk
    sudo chown mssql:mssql /var/opt/mssql/data/dbm_certificate.cer

    In the following diagram, ownership and group are set correctly for the certificate and key.

    

11. On the secondary replica, create a database login and password and create a master key.

    CREATE LOGIN dbm_login WITH PASSWORD = '<C0m9L3xP@55w0rd!>';
    CREATE USER dbm_user FOR LOGIN dbm_login;
    GO
    CREATE MASTER KEY ENCRYPTION BY PASSWORD = '<M@st3rKeyP@55w0rD!>'
    GO

12. On the secondary replica, restore the certificate you copied to /var/opt/mssql/data.

    CREATE CERTIFICATE dbm_certificate   
        AUTHORIZATION dbm_user
        FROM FILE = '/var/opt/mssql/data/dbm_certificate.cer'
        WITH PRIVATE KEY (
        FILE = '/var/opt/mssql/data/dbm_certificate.pvk',
        DECRYPTION BY PASSWORD = '<C0m9L3xP@55w0rd!>'
    )
    GO

13. On the primary replica, create an endpoint.

    CREATE ENDPOINT [Hadr_endpoint]
        AS TCP (LISTENER_IP = (0.0.0.0), LISTENER_PORT = 5022)
        FOR DATA_MIRRORING (
            ROLE = ALL,
            AUTHENTICATION = CERTIFICATE dbm_certificate,
            ENCRYPTION = REQUIRED ALGORITHM AES
            );
    ALTER ENDPOINT [Hadr_endpoint] STATE = STARTED;
    GRANT CONNECT ON ENDPOINT::[Hadr_endpoint] TO [dbm_login]
    GO

14. On the secondary replica, create the endpoint. Repeat the preceding script on the secondary replica to create the endpoint.

15. On the primary replica, create the AG with CLUSTER_TYPE = NONE.

    CREATE AVAILABILITY GROUP [ag1]
        WITH (CLUSTER_TYPE = NONE)
        FOR REPLICA ON
            N'<WinSQLInstance>' 
       	WITH (
            ENDPOINT_URL = N'tcp://<WinSQLInstance>:5022',
            AVAILABILITY_MODE = ASYNCHRONOUS_COMMIT,
       	    SEEDING_MODE = AUTOMATIC,
           	FAILOVER_MODE = MANUAL,
     	   SECONDARY_ROLE (ALLOW_CONNECTIONS = ALL)
       		),
            N'<LinuxSQLInstance>' 
        WITH (
       	    ENDPOINT_URL = N'tcp://<LinuxSQLInstance>:5022',
            AVAILABILITY_MODE = ASYNCHRONOUS_COMMIT,
            SEEDING_MODE = AUTOMATIC,
     	   FAILOVER_MODE = MANUAL,
     	   SECONDARY_ROLE (ALLOW_CONNECTIONS = ALL)
            )
    GO

    [!NOTE] The preceding script uses SEEDING_MODE = AUTOMATIC to create the AG. SQL Server 2017 introduces support for automatic seeding in an availability group even if the disk layout is different. This capability supports cross-platform availability groups. For more information, see Automatic Seeding - Disk Layout.

16. On the secondary replica, join the AG.

    ALTER AVAILABILITY GROUP [ag1] JOIN WITH (CLUSTER_TYPE = NONE)
    ALTER AVAILABILITY GROUP [ag1] GRANT CREATE ANY DATABASE
    GO

17. On the primary replica, run the SQL query to add the db to the AG.

    ALTER AVAILABILITY GROUP [ag1] ADD DATABASE <TestDB>
    GO

18. Verify that the database is getting populated on the secondary replica.

Fail over the primary replica

[!INCLUDEForce failover]

This article reviewed the steps to create a cross-platform AG to support migration or read-scale workloads. It can be used for manual disaster recovery. It also explained how to fail over the availability group. A cross-platform availability group uses cluster type NONE and does not support high availability because there is no cluster tool across platforms.

Next steps

Overview of Always On Availability Groups

SQL Server availability basics for Linux deployments