Monday Jul 02, 2012

AWS EC2 Oracle RDB - Storing and managing my data

When create an Oracle Database on the Amazon cloud you will need to store you database files somewhere on the EC2 cloud. There are basically three places where database files can be stored:
1. Local drive - This is the local drive that is part of the virtual server EC2 instance.
2. Elastic Block Storage (EBS) - Network attached storage that appears as a local drive.
3. Simple Storage Server (S3) - 'Storage for the Internet'.

S3 is not high speed and intended for store static document type files. S3 can also be used for storing static web page files. Local drives are ephemeral so not appropriate to be used as a database storage device. The leaves EBS which is the best place to store database files. EBS volumes appear as local disk drives. They are actually network-attached to an Amazon EC2 instance. In addition, EBS persists independently from the running life of a single Amazon EC2 instance. If you use an EBS backed instance for your database data, it will remain available after reboot but not after terminate. In many cases you would not need to terminate your instance but only stop it, which is equivalent of shutdown. In order to save your database data before you terminate an instance, you can snapshot the EBS to S3.

Using EBS as a data store you can move your Oracle data files from one instance to another. This allows you to move your database from one region or or zone to another. Unfortunately, to scale out your Oracle RDS on AWS you can not have read only replicas. This is only possible with the other Oracle relational database - MySQL. The free micro instances use EBS as its storage.

This is a very good white paper that has more details:
AWS Storage Options
This white paper also discusses: SQS, SimpleDB, and Amazon RDS in the context of storage devices. However, these are not storage devices you would use to store an Oracle database. This slide deck discusses a lot of information that is in the white paper:
AWS Storage Options slideshow

Monday Jun 11, 2012

Unidata and RDB migrations to Oracle

Have a couple of unique migrations that don't come along to often. They are Unidata and RDB migrations. The top three things that make these migration more challenging are:
1. No automated data migration tools - Because these migration don't happen that often, there are no tools in the market place to automated the data migration.
2. Application is tied to database - The application needs to be re-architected/re-engineered. Unidata Basic and COBOL for RDB. TSRI can migrate Basic to Java and PL/SQL. Transoft can migrate DEC COBOL to Java.
3. New client hardware potentially involved - Many Unidata and RDB based systems use 'green screens' as the front end. These are character based screens that will run on very old dumb terminals such as: Wyse and DEC 5250 terminals. The user interface can be replicated in a web browser but many times these old terminals do not support web browsers.

Thursday Jun 07, 2012

AWS EC2 Oracle RDB connection to Oracle Database Instance

Provisioning my Oracle database instance to AWS EC2 RDB was easy. Just a few clicks! However, getting my connection to my Oracle cloud database was not as easy. A couple things that are not obvious (using Oracle SQL Developer):
1. Need to set up a database security group.
2. Need to use end point for the host name.
This video is the best one on the internet to explain both points:
Youtube video on Oracle AWS RDB
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Migrating legacy client/server and mainframe technologies to the Oracle cloud.

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