Amazon announced the general availability of Amazon RDS Custom for SQL Server. The new service supports legacy, custom, and packaged applications that have dependencies on specific configurations and third-party tools and have historically been unable to move to a fully-managed database.
Last October, Amazon introduced RDS Custom, a managed service for applications that need access to the underlying operating system and database environment. With the latest announcement at re:Invent, SQL Server is now the second database engine supported on RDS Custom, after Oracle. The new option is designed for SQL Server applications that depend on customizations in corporate environments and content management systems, for example Microsoft SharePoint.
Channy Yun, principal developer advocate at AWS, explains how it works:
With RDS Custom for SQL Server, you can enable features that require elevated privileges like SQL Common Language Runtime (CLR), install specific drivers to enable heterogenous linked servers, or have more than 100 databases per instance.
Source: https://aws.amazon.com/blogs/aws/new-amazon-rds-custom-for-sql-server-is-generally-available/
The new service accepts connections using AWS Systems Manager Session Manager or a RDP client. It includes automating backups and provides monitoring and instance recovery. Brent Ozar, SQL Server expert, tweets:
This is intriguing for SQL Server folks who wanted to migrate to AWS RDS and Azure SQL DB, but couldn't because they wanted OS access, CLR, >100 databases per server, etc.
To apply customizations, administrators can pause the Automation Mode that performs backups and monitors the database, storage and EC2 status. On SQLSailor, Anup Warrier, senior solution architect at AWS, explains why this is a "new beginning" for SQL Server on RDS:
As a user, you never had access to the host operating system, you didn't have SA access to the instance, you couldn't run CLR and anything that needed elevated privileges was a no go. This is what is changing with RDS Custom for SQL Server. With RDS Custom, there is a notion of shared responsibility that's in play now. You are now allowed to make custom changes to the database, get access to the host etc. and do things that were never possible before.
It is now possible to configure HA on RDS Custom with Always On availability groups, setting up the primary DB instance to synchronously replicate data to standby instances in different availability zones, but the process requires a manual setup. Reviewing the requirements and limitations of Amazon RDS Custom, Nitzan Israeli, AWS cloud DBA at AllCloud, writes:
Two of the most important advantages we enjoyed in classic RDS (Read Replica HA solution and automatic minor version upgrades) were excluded from RDS Custom for SQL Server.
Amazon RDS Custom for SQL Server relies on AWS-supplied licenses and currently supports SQL Server 2019 Enterprise, Standard, and Web editions. The service is now available in a subset of regions, including North Virginia and Ireland. Pricing is higher than an equivalent classic RDS for SQL Server.