How to migrate your SQL Server database to Amazon RDS
Main Points - These are summarized notes, for a full details I've added the video at the bottom of these notes
- RDS fully managed service and provides as a managed experience.
The aim is to free up DBAs time involved on common DBA tasks , & move away from focusing on infrastructure & redeploy IT resources that deliver value .
RDS supports Aurora ,PostgreSQL,MySQL,MariaDB,SQL Server , Oracle
Automated Backups - Point in Recovery for your DB Instance
- Scheduled daily volume snapshots of entire instance - EBS block level snapshot , t-log backups every 5 mins. Different from native backups. Difference between EBS &SQL Server native backups is that EBS utilises
-Difference between application consistence & crash consistency . Snapshots are application consistent . Important point!
- For larger installs will separate TempDB onto instance store
- Manual Snapshot - can trigger at your own schedule , storage will be charges
Native Backups are supported
- backup & restore directly to & from Amazon S3 bucket. For example , if you want to move databases into \ or out of AWS
- supports compression
- Only full & diff backups
- Multi-file backup \restore - performance enhnacement
High Availability (multi-AZ)
- probably the most important feature
- part of the managed service experience
- under the hood relies on database mirroring (for older versions)& always on AG
- Backup retention > 0
- Full Recovery mode
- Synchronous replication
-Automatic & manual failover - application requires retry logic
-To support a fast(er) failover - the application must use a modern driver on the client side that can support multi-subnet failover = true & be connected to the listener endpoint. This way you can short-circuit the DNS propagation.
- There is no ability to send over the read traffic to the hot standby
- There is a separate feature to create read replicas , they are promotable
Cross-region Automated Backups - enable and select a second region of you choice to stream your backups\t-logs to a second region.
Integrated Windows Authentication - AWS managed AD is required
- can cross VPC and accont boundary
- it requires launching AWS AD Managed service
- Kerberos & NTLM
- When you join an RDS instance to the AWS AD managed service - it will only join as a FQDN.
Features supported- Integration Services
- Reporting Services
- Analysis Services
- SQL Server Agent Jobs
- DB Mail
-MS DTC
-Extended Events
The main point is that unless there is an exotic feature used than most SQL Server features are supported.
Building blocks RDS is built on
-Memory optimized Instances - multiple t-shirt sizes --> wide variety
- map your existing workload to the different t-shirt sizes
- Amazon Elastic Block Store
- solid state device attached to compute instance over the network
- gp2 v io1 - carefully assess your requirements , e.g max throughput/volume , Max IOS
Migrating to AWS
- Native & simple - covers large proportion of migrations but must accept downtime
- If can't tolerate downtime consider AWS Database Migration Service
- logical decoding of physical changes on AWS DMS Instance
- built with heterogeneous migrations
- Limited support for DDL , if schema in flux DMS may not be the best choice
- Transactional replication
- near0zero downtime
Post Migration Steps
- TempDB on local instance
- Parameter groups
- DBCC CHECKDB
-Configure backups
-CloudWatch, performance Insights
Monitoring on RDS
- Most scripts on-prem work unless they require "sa" access
-Performance Insights - boiled down to average active sessions - breakdown by waits , users , hosts
-CloudWatch metrics - collected at hypervisor level
- Third Party Tools ==> SentryOne,Redgate,SolarWinds ,Quest
-Enhanced metrics - up to 1 second granularity
Watch the full video of Migrate your SQL Server database to Amazon RDS