RDS FAQs

Q: Which relational database engines does Amazon RDS support?
Amazon RDS supports Amazon Aurora, MySQL, MariaDB, Oracle, SQL Server, and PostgreSQL database engines.

Q: How many DB instances can I run with Amazon RDS?
By default, customers are allowed to have up to a total of 40 Amazon RDS DB instances. Of those 40, up to 10 can be Oracle or SQL Server DB instances under the “License Included” model. All 40 can be used for Amazon Aurora, MySQL, MariaDB, PostgreSQL and Oracle under the “BYOL” model. Note that RDS for SQL Server has a limit of up to 100 databases on a single DB instance

If your application requires more DB instances, you can request additional DB instances.

Q: How many databases or schemas can I run within a DB instance?

• RDS for Amazon Aurora: No limit imposed by software
• RDS for MySQL: No limit imposed by software
• RDS for MariaDB: No limit imposed by software
• RDS for Oracle: 1 database per instance; no limit on number of schemas per database imposed by software
• RDS for SQL Server: Up to 100 databases per instance.
• RDS for PostgreSQL: No limit imposed by software.

Q: How do I import data into an Amazon RDS DB instance?
There are a number of simple ways to import data into Amazon RDS, such as with the mysqldump or mysqlimport utilities for MySQL; Data Pump, import/export or SQL Loader for Oracle; Import/Export wizard, full backup files (.bak files) or Bulk Copy Program (BCP) for SQL Server; or pg_dump for PostgreSQL.

In addition, AWS Database Migration Service can help you migrate databases to AWS easily and securely.

Q: Can I test my DB instance with a new version before upgrading?
Yes. You can do so by creating a DB snapshot of your existing DB instance, restoring from the DB snapshot to create a new DB instance, and then initiating a version upgrade for the new DB instance. You can then experiment safely on the upgraded copy of your DB instance before deciding whether or not to upgrade your original DB instance.

Q: Does Amazon RDS provide guidelines for deprecating database engine versions that are currently supported?

• We intend to support major version releases (e.g., MySQL 5.6, PostgreSQL 9.6) for at least 3 years after they are initially supported by Amazon RDS.
• We intend to support minor versions (e.g., MySQL 5.6.37, PostgreSQL 9.6.1) for at least 1 year after they are initially supported by Amazon RDS.

Periodically, we will deprecate major or minor engine versions. For major versions, this is typically when the version has moved to extended support or is no longer receiving software fixes or security updates. For minor versions, this is when a minor version has significant bugs or security issues that have been resolved in a later minor version.

Q: How will I be charged and billed for my use of Amazon RDS?
You pay only for what you use, and there are no minimum or setup fees. You are billed based on:

• DB instance hours – Based on the class (e.g. db.t2.micro, db.m4.large) of the DB instance consumed. Partial DB instance hours consumed are billed as full hours.
• Storage (per GB per month) – Storage capacity you have provisioned to your DB instance. If you scale your provisioned storage capacity within the month, your bill will be pro-rated.
• I/O requests per month – Total number of storage I/O requests you have (for Amazon RDS Magnetic Storage and Amazon Aurora only)
• Provisioned IOPS per month – Provisioned IOPS rate, regardless of IOPS consumed (for Amazon RDS Provisioned IOPS (SSD) Storage only)
• Backup Storage – Backup storage is the storage associated with your automated database backups and any customer-initiated database snapshots. Increasing your backup retention period or taking additional database snapshots increases the backup storage consumed by your database.
• Data transfer – Internet data transfer in and out of your DB instance.

Q: Why does my additional backup storage cost more than allocated DB instance storage?
The storage provisioned to your DB instance for your primary data is located within a single Availability Zone. When your database is backed up, the backup data (including transactions logs) is geo-redundantly replicated across multiple Availability Zones to provide even greater levels of data durability. The price for backup storage beyond your free allocation reflects this extra replication that occurs to maximize the durability of your critical backups.

Q: What is a reserved instance (RI)?
Amazon RDS reserved instances give you the option to reserve a DB instance for a one or three year term and in turn receive a significant discount compared to the on-demand instance pricing for the DB instance. There are three RI payment options — No Upfront, Partial Upfront, All Upfront — which enable you to balance the amount you pay upfront with your effective hourly price.

Q: How do I scale the compute resources and/or storage capacity associated with my Amazon RDS Database Instance?
You can scale the compute resources and storage capacity allocated to your DB instance with the AWS Management Console (selecting the desired DB instance and clicking the Modify button)

Q: Will my DB instance remain available during scaling?
The storage capacity allocated to your DB Instance can be increased while maintaining DB Instance availability. However, when you decide to scale the compute resources available to your DB instance up or down, your database will be temporarily unavailable while the DB instance class is modified. This period of unavailability typically lasts only a few minutes, and will occur during the maintenance window for your DB Instance, unless you specify that the modification should be applied immediately.

Q: How do I choose among the Amazon RDS storage types?
Choose the storage type most suited for your workload.
• High-performance OLTP workloads: Amazon RDS Provisioned IOPS (SSD) Storage
• Database workloads with moderate I/O requirements: Amazon RDS General Purpose (SSD) Storage

Q: What is the difference between automated backups and DB Snapshots?
The automated backup feature of Amazon RDS enables point-in-time recovery of your DB instance. When automated backups are turned on for your DB Instance, Amazon RDS automatically performs a full daily snapshot of your data (during your preferred backup window) and captures transaction logs (as updates to your DB Instance are made). When you initiate a point-in-time recovery, transaction logs are applied to the most appropriate daily backup in order to restore your DB instance to the specific time you requested. Amazon RDS retains backups of a DB Instance for a limited, user-specified period of time called the retention period, which by default is 7 days but can be set to up to 35 days. You can initiate a point-in-time restore and specify any second during your retention period, up to the Latest Restorable Time.
DB Snapshots are user-initiated and enable you to back up your DB instance in a known state as frequently as you wish, and then restore to that specific state at any time.

Q: Do I need to enable backups for my DB Instance or is it done automatically?
By default, Amazon RDS enables automated backups of your DB Instance with a 7 day retention period. Free backup storage is limited to the size of your provisioned database and only applies to active DB Instances. For example, if you have 100 GB of provisioned database storage over the month, we will provide 100 GB-months of backup storage at no additional charge.

Q: What is a backup window and why do I need it? Is my database available during the backup window?
During the backup window, storage I/O may be briefly suspended while the backup process initializes (typically under a few seconds) and you may experience a brief period of elevated latency. There is no I/O suspension for Multi-AZ DB deployments, since the backup is taken from the standby.

Q: What happens to my backups and DB snapshots if I delete my DB instance?
When you delete a DB instance, you can create a final DB snapshot upon deletion; if you do, you can use this DB snapshot to restore the deleted DB instance at a later date. Amazon RDS retains this final user-created DB snapshot along with all other manually created DB snapshots after the DB instance is deleted.
Automated backups are deleted when the DB instance is deleted. Only manually created DB Snapshots are retained after the DB Instance is deleted.

Q: How do I connect to an RDS DB Instance in VPC?
DB Instances deployed within a VPC can be accessed by EC2 Instances deployed in the same VPC. If these EC2 Instances are deployed in a public subnet with associated Elastic IPs, you can access the EC2 Instances via the internet.
DB Instances deployed within a VPC can be accessed from the Internet or from EC2 Instances outside the VPC via VPN or bastion hosts that you can launch in your public subnet, or using Amazon RDS’s Publicly Accessible option:
• To use a bastion host, you will need to set up a public subnet with an EC2 instance that acts as a SSH Bastion. This public subnet must have an internet gateway and routing rules that allow traffic to be directed via the SSH host, which must then forward requests to the private IP address of your RDS DB instance.
• To use public connectivity, simply create your DB Instances with the Publicly Accessible option set to yes. With Publicly Accessible active, your DB Instances within a VPC will be fully accessible outside your VPC by default. This means you do not need to configure a VPN or bastion host to allow access to your instances.
You can also set up a VPN Gateway that extends your corporate network into your VPC, and allows access to the RDS DB instance in that VPC. Refer to the Amazon VPC User Guide for more details.
We strongly recommend you use the DNS Name to connect to your DB Instance as the underlying IP address can change (e.g., during failover).

Q: Can I move my existing DB instances outside VPC into my VPC?
If your DB instance is not in a VPC, you can use the AWS Management Console to easily move your DB instance into a VPC. You can also take a snapshot of your DB Instance outside VPC and restore it to VPC by specifying the DB Subnet Group you want to use. Alternatively, you can perform a “Restore to Point in Time” operation as well.

Q: Can I move my existing DB instances from inside VPC to outside VPC?
Migration of DB Instances from inside to outside VPC is not supported. For security reasons, a DB Snapshot of a DB Instance inside VPC cannot be restored to outside VPC. The same is true with “Restore to Point in Time” functionality.

Q: Can I change the DB Subnet Group of my DB Instance?
An existing DB Subnet Group can be updated to add more subnets, either for existing Availability Zones or for new Availability Zones added since the creation of the DB Instance. Removing subnets from an existing DB Subnet Group can cause unavailability for instances if they are running in a particular AZ that gets removed from the subnet group.

Q: What privileges are granted to the master user for my DB Instance?
For MySQL, the default privileges for the master user include: create, drop, references, event, alter, delete, index, insert, select, update, create temporary tables, lock tables, trigger, create view, show view, alter routine, create routine, execute, trigger, create user, process, show databases, grant option.
For Oracle, the master user is granted the “dba” role. The master user inherits most of the privileges associated with the role
For SQL Server, a user that creates a database is granted the “db_owner” role.

Q: Can I encrypt connections between my application and my DB Instance using SSL/TLS?
Yes, this option is supported for all Amazon RDS engines.
Amazon RDS generates an SSL/TLS certificate for each DB Instance. Once an encrypted connection is established, data transferred between the DB Instance and your application will be encrypted during transfer.

Q: Can I encrypt data at rest on my Amazon RDS databases?
Amazon RDS supports encryption at rest for all database engines, using keys you manage using AWS Key Management Service (KMS). On a database instance running with Amazon RDS encryption, data stored at rest in the underlying storage is encrypted, as are its automated backups, read replicas, and snapshots. Encryption and decryption are handled transparently.
Amazon RDS for Oracle and SQL Server support those engines’ Transparent Data Encryption (TDE) technologies

Q: What are DB Parameter groups? How are they helpful?
A database parameter group (DB Parameter Group) acts as a “container” for engine configuration values that can be applied to one or more DB Instances. If you create a DB Instance without specifying a DB Parameter Group, a default DB Parameter Group is used. This default group contains engine defaults and Amazon RDS system defaults optimized for the DB Instance you are running.

Q: What is Option Groups?
Some DB engines offer additional features that make it easier to manage data and databases, and to provide additional security for your database. Amazon RDS uses option groups to enable and configure these features. An option group can specify features, called options, that are available for a particular Amazon RDS DB instance.

Q: Which metrics and processes can I monitor in Enhanced Monitoring?
Enhanced Monitoring captures your RDS instance system level metrics such as the CPU, memory, file system and disk I/O among others.

Q: Which instance types are supported by Enhanced Monitoring?
Enhanced Monitoring supports every instance type except t1.micro and m1.small.

Q: How far back can I see the historical metrics on the RDS console?
You can see the performance values for all the metrics up to 1 hour back, at a granularity of up to 1 second, based on your settings.

Q: When should I use CloudWatch instead of the RDS console dashboard?
You should use CloudWatch if you want to view historical data beyond what is available on the RDS console dashboard.

Q: Can I set up alarms and notifications based on specific metrics?
Yes. You can create an alarm in CloudWatch that sends a notification when the alarm changes state. The alarm watches a single metric over a time period that you specify, and performs one or more actions based on the value of the metric relative to the specified threshold over a number of time periods