AWS Relational Database Service
Whenever failover occurs, AWS RDS sends an SNS notification.
You can use API calls to find out the RDS events that occurred in the last 14 days.
Even, you can use CLI to view the last 14 days' events.
Using the AWS console, you can view only the last one-day events.
In case of
- OS Patching
- System Upgrades
- DB Scaling
These things happen on standby first then on Primary to avoid outage.
In Multi-AZ, Snapshots, and automated backups are done on standby instances to avoid I/O suspension on Primary.
RDS Multi-AZ Deployment-Maintenance
Firstly, perform maintenance on standby.
Now, convert standby into primary so that maintenance can be done on Primary.
You can manually upgrade a DB instance to a supported DB engine version from the AWS console as follows => RDS -> DB instance -> Modify DB -> Set DB Engine Version.
By default, the change will take effect during the next maintenance window.
You can force an immediate upgrade as well if you want.
In multi-AZ, version upgrades will be conducted on both primary and standby at the same time, which will cause an outage.
Do it during the maintenance window.
Back up and Restore RDS DB instances
There are 2 methods to backup and restore your RDS DB instances.
AWS RDS Automated Backup
User-initiated Manual Backup
Either you can take a backup of the entire DB instance or just the DB.
You can create storage volume snapshots of your entire DB instances.
Automated Backups by AWS, backup your DB data to multiple AZ to provide for data durability.
Select Automated Backup in AWS Console.
The backup is taken in Amazon S3.
Multi-AZ automated backups will be taken from the standby instance.
The DB instance must be in an "ACTIVE" state for Automated Backup.
RDS automatically backs up the DB instances daily, by creating a storage volume snapshot of your DB instance (fully daily snapshot) including the DB transaction logs.
You can decide when you would like to take the Backup window.
No additional charge for RDS backing up your DB instances.
For Multi-AZ deployment, backups are taken from the standby DB instance.
Automated backups are deleted when you delete your RDS DB instance.
An Outage occurs if you change the backup retention period from zero to non-zero value or the other way around.
The retention period of automated backup is 7 days (by default) via AWS console.
AWS Aurora is an Exception its default retention period is 1 day only.
If you configure your AWS DB via CLI or API, again the retention period is 1 day by default.
You can increase the retention period up to 35 days.
If you don't want backup you can put '0' in the retention period.