You signed in with another tab or window. Reload to refresh your session.You signed out in another tab or window. Reload to refresh your session.You switched accounts on another tab or window. Reload to refresh your session.Dismiss alert
Publisher and distributor databases on Azure SQL Database require [Managed Instance](http://docs.microsoft.com/azure/sql-database/sql-database-managed-instance) for more information, see [Replication with Azure SQL Database](http://docs.microsoft.com/sql/relational-databases/replication/replication-to-sql-database).
1
+
Publisher and distributor databases on Azure SQL Database require [Managed Instance](https://docs.microsoft.com/azure/sql-database/sql-database-managed-instance) for more information, see [Replication with Azure SQL Database](http://docs.microsoft.com/sql/relational-databases/replication/replication-to-sql-database).
Copy file name to clipboardExpand all lines: docs/includes/getssmedia.md
+1-1Lines changed: 1 addition & 1 deletion
Display the source diff
Display the rich diff
Original file line number
Diff line number
Diff line change
@@ -2,4 +2,4 @@ The download location for [!INCLUDE[ssnoversion](ssnoversion-md.md)] depends on
2
2
3
3
-**SQL Server Enterprise, Standard, and Express Editions** are licensed for production use. For Enterprise and Standard Editions, contact your software vendor for the installation media. You can find purchasing information and a directory of Microsoft partners on the [Microsoft purchasing website](https://www.microsoft.com/en-us/server-cloud/products/sql-server/overview.aspx).
4
4
5
-
-**Free editions** are available at [SQL Server Downloads](http://www.microsoft.com/sql-server/sql-server-downloads).
5
+
-**Free editions** are available at [SQL Server Downloads](https://www.microsoft.com/sql-server/sql-server-downloads).
Copy file name to clipboardExpand all lines: docs/includes/sql-server-ha-story.md
+8-8Lines changed: 8 additions & 8 deletions
Display the source diff
Display the rich diff
Original file line number
Diff line number
Diff line change
@@ -1,8 +1,8 @@
1
-
This article provides an overview of business continuity solutions for high availability and disaster recovery in SQL Server.
1
+
This article provides an overview of business continuity solutions for high availability and disaster recovery in SQL Server.
2
2
3
3
One common task everyone deploying SQL Server has to account for is making sure that all mission critical SQL Server instances and the databases within them are available when the business and end users need them, whether that is 9 to 5 or around the clock. The goal is to keep the business up and running with minimal or no interruption. This concept is also known as business continuity.
4
4
5
-
SQL Server 2017 introduces many new features or enhancements to existing ones, some of which are for availability. The biggest addition to SQL Server 2017 is the support for SQL Server on Linux distributions. For a full list of the new features in SQL Server 2017, see the topic [What's new in SQL Server](http://docs.microsoft.com/sql/sql-server/what-s-new-in-sql-server-2017).
5
+
SQL Server 2017 introduces many new features or enhancements to existing ones, some of which are for availability. The biggest addition to SQL Server 2017 is the support for SQL Server on Linux distributions. For a full list of the new features in SQL Server 2017, see the topic [What's new in SQL Server](https://docs.microsoft.com/sql/sql-server/what-s-new-in-sql-server-2017).
6
6
7
7
This article is focused on covering the availability scenarios in SQL Server 2017 as well as the new and enhanced availability features in SQL Server 2017. The scenarios include hybrid ones that will be able to span SQL Server deployments on both Windows Server and Linux, as well as ones that can increase the number of readable copies of a database. While this article does not cover availability options external to SQL Server, such as those provided by virtualization, everything discussed here applies to SQL Server installations inside a guest virtual machine whether in the public cloud or hosted by anon premises hypervisor server.
8
8
@@ -15,7 +15,7 @@ Availability groups, FCIs, and log shipping can be used in a variety of ways, an
15
15
* Migrations and upgrades
16
16
* Scaling out readable copies of one or more databases
17
17
18
-
Each section will discuss the relevant features that can be used for that particular scenario. The one feature not covered is [SQL Server replication](http://docs.microsoft.com/sql/relational-databases/replication/sql-server-replication). While not officially designated as an availability feature under the Always On umbrella, it is often used for making data redundant in certain scenarios. Replication will be added to SQL Server on Linux in a future release.
18
+
Each section will discuss the relevant features that can be used for that particular scenario. The one feature not covered is [SQL Server replication](https://docs.microsoft.com/sql/relational-databases/replication/sql-server-replication). While not officially designated as an availability feature under the Always On umbrella, it is often used for making data redundant in certain scenarios. Replication will be added to SQL Server on Linux in a future release.
19
19
20
20
> [!IMPORTANT]
21
21
> The SQL Server availability features do not replace the requirement to have a robust, well tested backup and restore strategy, the most fundamental building block of any availability solution.
@@ -148,7 +148,7 @@ One of the benefits of availability groups is that both high availability and di
148
148
![Availability Group][AG]
149
149
150
150
Outside of an availability group with a cluster type of none, an availability group requires that all replicas are part of the same underlying cluster whether it is a WSFC or Pacemaker. This means that in the picture above, the WSFC is stretched to work in two different data centers which adds complexity. regardless of the platform (Windows Server or Linux). Stretching clusters across distance adds complexity.
151
-
Introduced in SQL Server 2016, a distributed availability group allows an availability group to span availability groups configured on different clusters. This decouples the requirement to have the nodes all participate in the same cluster, which makes configuring disaster recovery much easier. For more information on distributed availability groups, see [Distributed availability groups](http://docs.microsoft.com/sql/database-engine/availability-groups/windows/distributed-availability-groups).
151
+
Introduced in SQL Server 2016, a distributed availability group allows an availability group to span availability groups configured on different clusters. This decouples the requirement to have the nodes all participate in the same cluster, which makes configuring disaster recovery much easier. For more information on distributed availability groups, see [Distributed availability groups](https://docs.microsoft.com/sql/database-engine/availability-groups/windows/distributed-availability-groups).
152
152
153
153
![Distributed Availability Group][DAG]
154
154
@@ -184,12 +184,12 @@ All variants of availability groups for migrations and upgrades allow the most t
184
184
185
185
Availability groups can provide minimal downtime during patching of the underlying OS by manually failing over the primary to a secondary replica while the patching is being completed. From an operating system perspective, doing this would be more common on Windows Server since often, but not always, servicing the underlying OS may require a reboot. Patching Linux sometimes needs a reboot, but it can be infrequent.
186
186
187
-
[Patching SQL Server instances participating in an availability group](http://docs.microsoft.com/sql/database-engine/availability-groups/windows/upgrading-always-on-availability-group-replica-instances) can also minimize downtime depending on how complex the availability group architecture is. To patch servers participating in an availability group, a secondary replica is patched first. Once the right number of replicas are patched, the primary replica is manually failed over to another node to do the upgrade. Any remaining secondary replicas at that point can be upgraded, too.
187
+
[Patching SQL Server instances participating in an availability group](https://docs.microsoft.com/sql/database-engine/availability-groups/windows/upgrading-always-on-availability-group-replica-instances) can also minimize downtime depending on how complex the availability group architecture is. To patch servers participating in an availability group, a secondary replica is patched first. Once the right number of replicas are patched, the primary replica is manually failed over to another node to do the upgrade. Any remaining secondary replicas at that point can be upgraded, too.
188
188
189
189
### Always on failover cluster instances
190
190
191
191
FCIs on their own cannot assist with a traditional migration or upgrade; an availability group or log shipping would have to be configured for the databases in the FCI and all other objects accounted for. However, FCIs under Windows Server are still a popular option for when the underlying Windows Servers need to be patched. A manual failover can be initiated, which means a brief outage instead of having the instance completely unavailable for the entire time Windows Server is being patched.
192
-
An FCI can be upgraded in place to SQL Server 2017. For information, see [Upgrade a SQL Server Failover Cluster Instance](http://docs.microsoft.com/sql/sql-server/failover-clusters/windows/upgrade-a-sql-server-failover-cluster-instance).
192
+
An FCI can be upgraded in place to SQL Server 2017. For information, see [Upgrade a SQL Server Failover Cluster Instance](https://docs.microsoft.com/sql/sql-server/failover-clusters/windows/upgrade-a-sql-server-failover-cluster-instance).
193
193
194
194
### Log shipping
195
195
@@ -201,7 +201,7 @@ Similar to availability groups, log shipping can provide a way to switch to anot
201
201
202
202
There are two other deployment methods for SQL Server on Linux: containers and using Azure (or another public cloud provider). The general need for availability as presented throughout this paper exists regardless of how SQL Server is deployed. These two methods have some special considerations when it comes to making SQL Server highly available.
203
203
204
-
[Containers using Docker](http://docs.microsoft.com/sql/linux/quickstart-install-connect-docker) are a new way of deploying SQL Server, either for Windows Server or Linux. A container is a complete image of SQL Server that is ready to run. However, there is currently no native support for clustering, and thus, direct high availability or disaster recovery. Currently, the options to make SQL Server databases available using containers would be log shipping and backup and restore. While an availability group with a cluster type of None can be configured, as noted earlier, it is not considered a true availability configuration. Microsoft is looking at ways to enable availability groups or FCIs using containers.
204
+
[Containers using Docker](https://docs.microsoft.com/sql/linux/quickstart-install-connect-docker) are a new way of deploying SQL Server, either for Windows Server or Linux. A container is a complete image of SQL Server that is ready to run. However, there is currently no native support for clustering, and thus, direct high availability or disaster recovery. Currently, the options to make SQL Server databases available using containers would be log shipping and backup and restore. While an availability group with a cluster type of None can be configured, as noted earlier, it is not considered a true availability configuration. Microsoft is looking at ways to enable availability groups or FCIs using containers.
205
205
206
206
If you are using containers today, if the container is lost, depending on the container platform, it can be deployed again and attached to the shared storage that was used. Some of this mechanism is provided by the container orchestrator. While this does provide some resiliency, there will be some downtime associated with database recovery and is not truly highly available as it would be if using an availability group or FCI.
207
207
@@ -230,7 +230,7 @@ Since log shipping is just based on backup and restore, and there are no differe
230
230
231
231
## <aname = "ReadScaleOut"></a> read-scale
232
232
233
-
Since their introduction in SQL Server 2012, secondary replicas have had the ability to be used for read-only queries. There are two ways that can be achieved with an availability group: by allowing direct access to the secondary as well as [configuring read only routing](http://docs.microsoft.com/sql/database-engine/availability-groups/windows/configure-read-only-routing-for-an-availability-group-sql-server) which requires the use of the listener. SQL Server 2016 introduced the ability to load balance read-only connections via the listener using a round robin algorithm, allowing read-only requests to be spread across all readable replicas.
233
+
Since their introduction in SQL Server 2012, secondary replicas have had the ability to be used for read-only queries. There are two ways that can be achieved with an availability group: by allowing direct access to the secondary as well as [configuring read only routing](https://docs.microsoft.com/sql/database-engine/availability-groups/windows/configure-read-only-routing-for-an-availability-group-sql-server) which requires the use of the listener. SQL Server 2016 introduced the ability to load balance read-only connections via the listener using a round robin algorithm, allowing read-only requests to be spread across all readable replicas.
234
234
235
235
> [!NOTE]
236
236
Readable secondary replicas is a feature only in Enterprise Edition, and each instance hosting a readable replica would need a SQL Server license.
Copy file name to clipboardExpand all lines: docs/includes/ss-linux-cluster-availability-group-create-prereq.md
+3-3Lines changed: 3 additions & 3 deletions
Display the source diff
Display the rich diff
Original file line number
Diff line number
Diff line change
@@ -1,4 +1,4 @@
1
-
## Prerequisites
1
+
## Prerequisites
2
2
3
3
Before you create the availability group, you need to:
4
4
@@ -77,7 +77,7 @@ ALTER EVENT SESSION AlwaysOn_health ON SERVER WITH (STARTUP_STATE=ON);
77
77
GO
78
78
```
79
79
80
-
For more information about this XE session, see [AlwaysOn extended events](http://msdn.microsoft.com/library/dn135324.aspx).
80
+
For more information about this XE session, see [AlwaysOn extended events](https://msdn.microsoft.com/library/dn135324.aspx).
81
81
82
82
## Create a certificate
83
83
@@ -166,6 +166,6 @@ The TCP port on the firewall must be open for the listener port.
166
166
>[!IMPORTANT]
167
167
>For the SQL Server 2017 release, the only authentication method supported for the database mirroring endpoint is `CERTIFICATE`. The `WINDOWS` option will be enabled in a future release.
168
168
169
-
For more information, see [The database mirroring endpoint (SQL Server)](http://msdn.microsoft.com/library/ms179511.aspx).
169
+
For more information, see [The database mirroring endpoint (SQL Server)](https://msdn.microsoft.com/library/ms179511.aspx).
Copy file name to clipboardExpand all lines: docs/includes/ss-linux-cluster-availability-group-manage-sync-commit.md
+1-1Lines changed: 1 addition & 1 deletion
Display the source diff
Display the rich diff
Original file line number
Diff line number
Diff line change
@@ -17,7 +17,7 @@ Note that this is only guaranteed to work as long as at least one replica availa
17
17
18
18
In the following case, an availability group may still be vulnerable to data loss. In a cluster that includes five nodes, if there is an availability group with replicas on three instances of SQL Server, it is possible for the primary replica and one secondary replica to be ahead of the other secondary replica. When they are ahead, the `sequence_number` in `sys.availability_groups` will be higher than the other replicas. In this condition, if the two replicas lose connectivity with the rest of the cluster, Pacemaker may see the remaining three nodes as a quorum, and allow the latent replica to promote itself to primary. In this situation, there is potential for data loss.
19
19
20
-
sql2017 introduces a new feature to force a certain number of secondaries to be available before any transactions can be committed on the primary. `REQUIRED_COPIES_TO_COMMIT` allows you to set a number of replicas that must commit to secondary replica database transaction logs before a transaction can proceed. You can use this option with `CREATE AVAILABILITY GROUP` or `ALTER AVAILABILITY GROUP`. See [CREATE AVAILABILITY GROUP](http://msdn.microsoft.com/library/ff878399.aspx).
20
+
sql2017 introduces a new feature to force a certain number of secondaries to be available before any transactions can be committed on the primary. `REQUIRED_COPIES_TO_COMMIT` allows you to set a number of replicas that must commit to secondary replica database transaction logs before a transaction can proceed. You can use this option with `CREATE AVAILABILITY GROUP` or `ALTER AVAILABILITY GROUP`. See [CREATE AVAILABILITY GROUP](https://msdn.microsoft.com/library/ff878399.aspx).
21
21
22
22
To avoid the potential of data loss described above set `REQUIRED_COPIES_TO_COMMIT` to the maximum number of synchronized replicas. Upcoming releases will have built in logic to handle setting `REQUIRED_COPIES_TO_COMMIT` automatically.
23
23
When `REQUIRED_COPIES_TO_COMMIT` is set, transactions at the primary replica databases will wait until the transaction is committed on the required number of synchronous secondary replica database transaction logs. If enough synchronous secondary replicas are not online, transactions will stop until communication with sufficient secondary replicas resume.
0 commit comments