Expert Oracle Exadata - Parent Directory

CHAPTER 1 WHAT IS EXADATA?Limited Standard Configurations: Most DW Appliances only come in a verylimited set of configurations (small, medium, and large, for example). Exadata isno different. There are currently only four possible configurations. This hasrepercussions with regards to supportability. It means if you call support andtell them you have an X2-2 Half Rack, the support people will immediatelyknow all they need to know about your hardware. This provides benefits to thesupport personnel and the customers in terms of how quickly issues can beresolved.Regardless of the similarities, Oracle does not consider Exadata to be a DW Appliance, even thoughthere are many shared characteristics. Generally speaking, this is because Exadata provides a fullyfunctional Oracle database platform with all the capabilities that have been built into Oracle over theyears, including the ability to run any application that currently runs on an Oracle database and inparticular to deal with mixed workloads that demand a high degree of concurrency, which DWAppliances are generally not equipped to handle. Kevin Says: Whether Exadata is or is not an appliance is a common topic of confusion when people envisionwhat Exadata is. The Oracle Exadata Database Machine is not an appliance. However, the storage grid doesconsist of Exadata Storage Server cells—which are appliances.OLTP MachineThis description is a bit of a marketing ploy aimed at broadening Exadata’s appeal to a wider marketsegment. While the description is not totally off-base, it is not as accurate as some other monikers thathave been assigned to Exadata. It brings to mind the classic quote:It depends on what the meaning of the word “is” is.—Bill ClintonIn the same vein, OLTP (Online Transaction Processing) is a bit of a loosely defined term. Wetypically use the term to describe workloads that are very latency-sensitive and characterized by singleblockaccess via indexes. But there is a subset of OLTP systems that are also very write-intensive anddemand a very high degree of concurrency to support a large number of users. Exadata was not designedto be the fastest possible solution for these write-intensive workloads. However, it’s worth noting thatvery few systems fall neatly into these categories. Most systems have a mixture of long-running,throughput-sensitive SQL statements and short-duration, latency-sensitive SQL statements. Which leadsus to the next view of Exadata.Consolidation PlatformThis description pitches Exadata as a potential platform for consolidating multiple databases. This isdesirable from a total cost of ownership (TCO) standpoint, as it has the potential to reduce complexity(and therefore costs associated with that complexity), reduce administration costs by decreasing thenumber of systems that must be maintained, reduce power usage and data center costs through6