Pat Shuff's Blog

Amazon RDS

Today we are going to look at Amazon RDS as a solution for running the Oracle Database in the cloud. According to the Amazon RDS website RDS is an easy to set up, operate, and scale a relational database in the cloud. It provides cost-efficient and resizable capacity while managing time-consuming database administration tasks, freeing you up to focus on your applications and business. Amazon RDS provides you six familiar database engines to choose from, including Amazon Aurora, Oracle, Microsoft SQL Server, PostgreSQL, MySQL and MariaDB.

We are going to focus on the Application Express using Amazon RDS so we won't dive deep into the different shapes available and skim over pricing in this discussion. With Amazon RDS, you can deploy multiple editions of Oracle Database. You can run Amazon RDS for Oracle under two different licensing models – “License Included” and “Bring-Your-Own-License (BYOL)”. In the "License Included" service model, you do not need separately purchased Oracle licenses; the Oracle Database software has been licensed by AWS. "License Included" pricing. Oracle has a policy paper on cloud licensing. It is important to understand database licensing and how it applies to hard partitions, soft partitions, and cloud environments.

Automated backups are turned on by default and snapshots are enabled as they are for EC2 instances. You can scale up and down processors as well as scale up and down IOPs allocated for the Oracle instance. You can use Amazon VPC to connect this instance to your data center as well as Amazon HSM to encrypt your data.

The two biggest issues that you need to consider with any cloud strategy is security and lock in. Backups are done from Amazon zone to Amazon zone. Oracle RMAN is not available as a backup mechanism and neither is the Oracle Advanced Security. Encryption is done at the disk layer and not inside the database. Amazon strips the ability for you to replicate your data back to your data center or use your security keys to encrypt your data. You have to use their backup tools and their encryption technology using their keys to protect your data. Key management and key rotation become an issue for security sensitive applications and data sets.

Amazon RDS pricing is available on the Amazon web page. Pricing starts at $0.035/hour for a quarter virtual processor and 1 GB of RAM and goes up to $3.64/hour for a standard instance and high memory instance. This pricing is for Standard Edition One of the database and includes the database license. For Standard Edition Two and Enterprise Edition, you must bring your own license. Pricing for this model starts at $0.017/hour and grows to $7.56/hour. You can also pay for a reserved account that dedicates an instance to you for as low as $99/year growing upto $33.8K/year. Data ingestion to load the database is free but there is a cost associated with copying data from the RDS instance to your client at a charge ranging from $0.09/GB/month to $0.05/GB/month at higher transfer rates. We recommend that you use the Amazon AWS Pricing Calculator to figure out your monthly charges.

To create an RDS instance, we go to the AWS Console and select the RDS instance. From here we select the "Get Started Now" button in the middle of the screen. We then select the Oracle tab and the Oracle EE Select button. To save money we are going to select the Dev/Test version but both effectively do the same thing. The key difference in the dev or production selections are minor. The production instance preloads the Instance Class with a m3.xlarge, Multi-AZ turned on, and Storage Type set to SSD. There is one item displayed, Provisioned IOPS, in the create screen that is not in the dev option. We can make the dev option look just like the production option by selecting a large enough instance and turning on Multi-AZ in the next screen.

Production instance

Development instance

We are going to select the latest version, an instance with a little memory, general purpose storage to get 3 IOPS/GB since this is a test instance, and define our ORACLE_SID and account to access the instance.

The next screen is what defines this as Platform as a Service and not an EC2 instance with an AMI. We automatically open ports in the operating system and network access by opening port 1521 for the listener, we confirm the OID, select the character name set, turn on or off encryption in the storage, define the backup window and retention period, as well as patching policies. We are going to accept the defaults and not change anything. The one thing that Amazon does that Oracle does not is define the VPC connection when you define the database. Oracle requires a separate step to create a VPN connection. If you select Multi-AZ, I would have expected to see a selection of zones that you can replicate across. For all of the options that I selected, the Availability Zone was greyed out and I could not select the failover zone. I assume that you have to pre-define a zone relationship to make this work but it was never an option for my tests.

Once you click on Create Instance you see a splash screen and can go to the RDS monitor to look at instances that you have launched.

Once the provisioning is finished we can look at the connection details and use SQL Developer to connect to the instance. It is important to note here that we do not have SSH or command line access to this database instance. We only have access through port 1521 and do not have sys, system, or sysdba access to this database instance.

We can connect with SQL Developer by using the details from the previous screen to get the endpoint, port, and instance identifier.

The first thing to note with the database connection is that the RDS instance does not have a container. You are connecting to the base instance and pluggable databases are not available. If you have purchased the multi-tenant option for the database, RDS is not an option. If we dive into the database configuration we note that auditing is turned off for RDS. The primary reason for this is that you would not have access to the audit logs since you don't have file system access to read the logs. If you look at the control management access packs parameter, diagnostics and tuning is turned on and enables. This means that you have to purchase these additional packages to run in RDS. There is no way to turn this option off and these licenses are not included as part of the RDS usage license. You also do not have access to this data but have to go through the monitor screens to view this data and sql developer. The database compatability type is set to 12.0.0. Given that we do not have sys access we can not run in compatability mode to help migrate 11g databases into a container. Some important parameters are set that we can not change; enable_ddl_logging is false disabling DataGuard, enable_goldengate_replication is false disabling Golden Gate, enable_pluggable_database is false disabling Multi-Tenant. Default_tbs_type is set to bigfile and there are no mechanisms to change this.

It is important to figure out what the default user that we created can and can't do when managing the database. The roles assigned to this user are rather limited. We can compare the roles of the oracle user (the one we created) to the sys user. Note that the oracle roles are a short list.

The RDS Option Documentation talks about connecting to enterprise manager and application express. We were not able to connect to ports 1158 or 5500 as suggested. My gut says that this has to do with the port routing rules that were created by default.

If we are running out of table space we can modify the existing instance and grow the storage. This is done by going to the RDS instance page and selecting modify instance. You type in the new storage size and click apply immediately.

Once the modification finishes we can see the new storage in the details page in the RDS console.

We should note that we do not see the addition to the tablespace because it is added to the filesystem but the tablespaces are all configured to auto extend and consume all available space. Unfortunately, this makes it look like all of the tablespace is full and our used percent will always be relatively high for the files that our tables are stored. We need to monitor disk usage separately with a different part of the RDS console.

In summary, you can run the Oracle database in Amazon RDS. There are limitations and issues that you need to be aware of when doing this. Some of the features are limited and not available to you. Some of the features are required which you might not be using today. If you are running an application server in EC2, running the database in RDS makes sense. The intention of this blog is not to tear down one implementation and elevate another but to elevate discussion on what to look out for when you have decided to run in a specific cloud instance. Up next, how does Amazon RDS differ from Amazon EC2 with a pre-configured AMI.

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