00_Introduction_JFV14_00_Introduction_JFV14.ppt

Editor's Notes

• #2: Overview The material in this course is designed to provide basic information that is needed to plan or manage Oracle Database 10g for Real Application Clusters. The lessons and practices are designed to build on your knowledge of Oracle used in a nonclustered environment. The material does not cover basic architecture and database management; these topics are addressed by the Oracle Database 10g administration courses offered by Oracle University. If your background does not include working with a current release of the Oracle database, then you should consider taking such training before attempting this course. The practices provide an opportunity for you to work with the features of the database that are unique to Real Application Clusters.
• #3: What Is a Cluster? A cluster consists of two or more independent, but interconnected, servers. Several hardware vendors have provided cluster capability over the years to meet a variety of needs. Some clusters were only intended to provide high availability by allowing work to be transferred to a secondary node if the active node fails. Others were designed to provide scalability by allowing user connections or work to be distributed across the nodes. Another common feature of a cluster is that it should appear to an application as if it were a single server. Similarly, management of several servers should be as similar to the management of a single server as possible. The cluster management software provides this transparency. For the nodes to act as if they were a single server, files must be stored in such a way that they can be found by the specific node that needs them. There are several different cluster topologies that address the data access issue, each dependent on the primary goals of the cluster designer. The interconnect is a physical network used as a means of communication between each node of the cluster. In short, a cluster is a group of independent servers that cooperate as a single system.
• #4: What Is Oracle Real Application Clusters? Real Application Clusters is a software that enables you to use clustered hardware by running multiple instances against the same database. The database files are stored on disks that are either physically or logically connected to each node, so that every active instance can read from or write to them. The Real Application Clusters software manages data access, so that changes are coordinated between the instances and each instance sees a consistent image of the database. The cluster interconnect enables instances to pass coordination information and data images between each other. This architecture enables users and applications to benefit from the processing power of multiple machines. RAC architecture also achieves redundancy in the case of, for example, a system crashing or becoming unavailable; the application can still access the database on any surviving instances.
• #5: Why Use RAC? Oracle Real Application Clusters (RAC) enables high utilization of a cluster of standard, low-cost modular servers such as blades. RAC offers automatic workload management for services. Services are groups or classifications of applications that comprise business components corresponding to application workloads. Services in RAC enable continuous, uninterrupted database operations and provide support for multiple services on multiple instances. You assign services to run on one or more instances, and alternate instances can serve as backup instances. If a primary instance fails, Oracle moves the services from the failed instance to a surviving alternate instance. Oracle also automatically load-balances connections across instances hosting a service. RAC harnesses the power of multiple low-cost computers to serve as a single large computer for database processing, and provides the only viable alternative to large-scale SMP for all types of applications. RAC, which is based on a shared-disk architecture, can grow and shrink on demand without the need to artificially partition data among the servers of your cluster. RAC also offers a single-button addition and removal of servers to a cluster. Thus, you can easily provide or remove a server to or from the database.
• #6: Clusters and Scalability If your application scales transparently on symmetric multiprocessing (SMP) machines, then it is realistic to expect it to scale well on RAC, without having to make any changes to the application code. RAC eliminates the database instance, and the node itself, as a single point of failure, and ensures database integrity in the case of such failures. Following are some scalability examples: Allow more simultaneous batch processes. Allow larger degrees of parallelism and more parallel executions to occur. Allow large increases in the number of connected users in online transaction processing (OLTP) systems.
• #7: Level of Scalability Successful implementation of cluster databases requires optimal scalability on four levels: Hardware scalability: Interconnectivity is the key to hardware scalability, which greatly depends on high bandwidth and low latency. Operating system scalability: Methods of synchronization in the operating system can determine the scalability of the system. In some cases, potential scalability of the hardware is lost because of the operating system’s inability to handle multiple resource requests simultaneously. Database management system scalability: A key factor in parallel architectures is whether the parallelism is affected internally or by external processes. The answer to this question affects the synchronization mechanism. Application scalability: Applications must be specifically designed to be scalable. A bottleneck occurs in systems in which every session is updating the same data most of the time. Note that this is not RAC specific and is true on single-instance system too. It is important to remember that if any of the above areas are not scalable (no matter how scalable the other areas are), then parallel cluster processing may not be successful. A typical cause for the lack of scalability is one common shared resource that must be accessed often. This causes the otherwise parallel operations to serialize on this bottleneck. A high latency in the synchronization increases the cost of synchronization, thereby counteracting the benefits of parallelization. This is a general limitation and not a RAC-specific limitation.
• #8: Scaleup and Speedup Scaleup is the ability to sustain the same performance levels (response time) when both workload and resources increase proportionally: Scaleup=(volume parallel)/(volume original)–time for ipc For example, if 30 users consume close to 100 percent of the CPU during normal processing, then adding more users would cause the system to slow down due to contention for limited CPU cycles. However, by adding CPUs, you can support extra users without degrading performance. Speedup is the effect of applying an increasing number of resources to a fixed amount of work to achieve a proportional reduction in execution times: Speedup=(time original)/(time parallel)–time for ipc Speedup results in resource availability for other tasks. For example, if queries usually take ten minutes to process and running in parallel reduces the time to five minutes, then additional queries can run without introducing the contention that might occur were they to run concurrently. Note: ipc is the abbreviation for interprocess communication.
• #9: Speedup/Scaleup and Workloads The type of workload determines whether scaleup or speedup capabilities can be achieved using parallel processing. Online transaction processing (OLTP) and Internet application environments are characterized by short transactions that cannot be further broken down, and therefore, no speedup can be achieved. However, by deploying greater amounts of resources, a larger volume of transactions can be supported without compromising the response. Decision support systems (DSS) and parallel query options can attain speedup, as well as scaleup, because they essentially support large tasks without conflicting demands on resources. The parallel query capability within Oracle can also be leveraged to decrease overall processing time of long-running queries and to increase the number of such queries that can be run concurrently. In an environment with a mixed workload of DSS, OLTP, and reporting applications, scaleup can be achieved by running different programs on different hardware. Speedup is possible in a batch environment, but may involve rewriting programs to use the parallel processing capabilities.
• #10: A History of Innovation Oracle Database 10g and the specific new manageability enhancements provided by Oracle RAC 10g enable RAC for everyone—all types of applications and enterprise grids, the basis for fourth-generation computing. Enterprise grids are built from large configurations of standardized, commodity-priced components: processors, network, and storage. With Oracle RAC’s cache fusion technology, the Oracle database adds to this the highest levels of availability and scalability. Also, with Oracle RAC 10g, it becomes possible to perform dynamic provisioning of nodes, storage, CPUs, and memory to maintain service levels more easily and efficiently. Enterprise grids are the data centers of the future and enable business to be adaptive, proactive, and agile for the fourth generation. The next major transition in computing infrastructure is going from the era of big SMPs to the era of grids.
• #11: Course Objectives This course is designed to give you the necessary information to successfully administer Real Application Clusters. You install Oracle Database 10g with Oracle Universal Installer (OUI) and create your database with the Database Configuration Assistant (DBCA). This ensures that your RAC environment has the optimal network configuration, database structure, and parameter settings for the environment that you selected. As a DBA, after installation your tasks are to administer your RAC environment at three levels: Instance administration Database administration Cluster administration Throughout this course you use various tools to administer each level of RAC: Oracle Enterprise Manager 10g Database Control to perform administrative tasks whenever feasible Task-specific GUIs such as the Database Configuration Assistant (DBCA) and the Virtual Internet Protocol Configuration Assistant (VIPCA) Command-line tools such as SQL*Plus, Recovery Manager, Server Control (SRVCTL).
• #12: Typical Schedule The lessons in this guide are arranged in the order that you will probably study them in class, and are grouped into the topic areas that are shown in the slide. The individual lessons are ordered so that they lead from more familiar to less familiar areas. The related practices are designed to let you explore increasingly powerful features of a Real Application Clusters database. In some cases, the goals for the lessons and goals for the practices are not completely compatible. Your instructor may, therefore, choose to teach some material in a different order than found in this guide. However, if your instructor teaches the class in the order in which the lessons are printed in this guide, then the class should run approximately as shown in this schedule.