1 Introduction to Oracle Database 2 Day + Real Application Clusters Guide



About Oracle Grid Infrastructure for a Cluster and Oracle RAC

Starting with Oracle Database
11g Release
2, Oracle Clusterware and Oracle ASM are installed into a single home directory, which is called the Grid home. Oracle Grid Infrastructure for a cluster refers to the installation of the combined products. Oracle Clusterware and Oracle ASM are still individual
products, and are referred to by those names.

关于适用于群集和Oracle RAC的Oracle Grid
Infrastructure

从Oracle数据库11g第2版​​开始，Oracle
Clusterware和Oracle ASM安装在一个名为Grid home的主目录中。集群的Oracle Grid Infrastructure指的是组合产品的安装。Oracle Clusterware和Oracle ASM仍然是单独的产品，并以这些名称引用。

Oracle Clusterware enables
servers, referred to as hosts or nodes,
to operate as if they are one server, commonly referred to as a cluster.
Although the servers are standalone servers, each server has additional processes that communicate with other servers. In this way the separate servers appear as if they are one server to applications and end users. Oracle Clusterware provides the infrastructure
necessary to run Oracle RAC. The combined processing power of the multiple servers provides greater availability, throughput, and scalability than is available from a single server.
Oracle Clusterware使服务器（称为主机或节点）能够像一个服务器一样运行，通常称为群集。虽然服务器是独立的服务器，但每台服务器都有其他进程与其他服务器通信。这样，单独的服务器就好像它们是应用程序和最终用户的一台服务器一样。Oracle集群件提供运行Oracle
RAC所需的基础架构。多台服务器的综合处理能力提供了比单台服务器更高的可用性，吞吐量和可扩展性。

About Oracle Automatic Storage Management

Oracle ASM is an integrated,
high-performance volume manager and file system. With Oracle Database 11g Release
2, Oracle ASM adds support for storing the Oracle Clusterware OCR and voting disk files, also a general purpose cluster file system called Oracle Automatic Storage Management Cluster File System (Oracle ACFS). Oracle ASM is based on the principle that the
database should manage storage instead of requiring an administrator to do it. Oracle ASM eliminates the need for you to directly manage potentially thousands of Oracle database files.

About Oracle Automatic Storage Management

Oracle ASM is an integrated,
high-performance volume manager and file system. With Oracle Database 11g Release
2, Oracle ASM adds support for storing the Oracle Clusterware OCR and voting disk files, also a general purpose cluster file system called Oracle Automatic Storage Management Cluster File System (Oracle ACFS). Oracle ASM is based on the principle that the
database should manage storage instead of requiring an administrator to do it. Oracle ASM eliminates the need for you to directly manage potentially thousands of Oracle database files.
Oracle ASM是一个集成的高性能卷管理器和文件系统。借助Oracle
Database 11g第2版​​，Oracle
ASM增加了对存储Oracle Clusterware OCR和Voting磁盘文件的支持，该文件也是称为Oracle自动存储管理群集文件系统（Oracle ACFS）的通用群集文件系统。Oracle
ASM基于数据库应该管理存储而不需要管理员来完成的原则。Oracle ASM不需要您直接管理数千个Oracle数据库文件。



Oracle ASM groups the disks
in your storage system into one or more disk groups. You manage a small set of disk groups and Oracle ASM automates the placement of the database files within those disk groups. Oracle Cluster Registry (OCR) and voting disks can also be placed on Oracle ASM
diskgroups. When using Oracle Real Application Clusters (Oracle RAC), each instance must have access to the data files and recovery files for the Oracle RAC database. Using Oracle Automatic Storage Management (Oracle ASM) is an easy way to satisfy this requirement.

Oracle ASM groups the disks
in your storage system into one or more disk groups. You manage a small set of disk groups and Oracle ASM automates the placement of the database files within those disk groups. Oracle Cluster Registry (OCR) and voting disks can also be placed on Oracle ASM
diskgroups. When using Oracle Real Application Clusters (Oracle RAC), each instance must have access to the data files and recovery files for the Oracle RAC database. Using Oracle Automatic Storage Management (Oracle ASM) is an easy way to satisfy this requirement.
Oracle ASM将存储系统中的磁盘分组为一个或多个磁盘组。您管理一小组磁盘组，并且Oracle
ASM自动将数据库文件放置在这些磁盘组中。Oracle集群注册表（OCR）和投票磁盘也可以放置在Oracle ASM磁盘组上。在使用Oracle
Real Application Clusters（Oracle RAC）时，每个实例必须能够访问Oracle RAC数据库的数据文件和恢复文件。使用Oracle自动存储管理（Oracle ASM）是满足此要求的简单方法。

In Figure
1-1, the normal redundancy disk group stored in Oracle ASM contains three failure
groups (shown as three disks) to store the voting disk and OCR files for Oracle Clusterware. Because the voting disk records which nodes are currently members of the cluster, there must be at least three voting disks for a two-node cluster. If the Oracle ASM
disk group did not contain the voting disk and OCR files, then you could have a normal redundancy disk group with only two failure groups.
在图1-1中，存储在Oracle
ASM中的正常冗余磁盘组包含三个故障组（显示为三个磁盘），用于存储Oracle Clusterware的投票磁盘和OCR文件。由于投票磁盘记录哪些节点当前是群集的成员，因此双节点群集必须至少有三个投票磁盘。如果Oracle ASM磁盘组不包含投票磁盘和OCR文件，那么您可以拥有一个只有两个故障组的正常冗余磁盘组。



Oracle ASM provides the following
benefits:
Striping—Oracle
ASM spreads data evenly across all disks in a disk group to optimize performance and utilization. This even distribution of database files eliminates the need for regular monitoring and I/O performance tuning.
Striping- Oracle
ASM将数据均匀分布在磁盘组中的所有磁盘上，以优化性能和利用率。数据库文件的这种均匀分布消除了对定期监视和I
/ O性能调整的需求。

Mirroring—Oracle
ASM increases data availability by optionally mirroring any file. Oracle ASM mirrors at the file level, unlike operating system mirroring, which mirrors at the disk level. Mirroring means keeping redundant copies, or mirrored copies, of each extent of the
file, to help avoid data loss caused by disk failures. The mirrored copy of each file extent is always kept on a different disk from the original copy. If a disk fails, then Oracle ASM continues to access affected files by accessing mirrored copies on the
surviving disks in the disk group.
镜像 -Oracle
ASM通过可选地镜像任何文件来提高数据可用性。与操作系统镜像不同，Oracle ASM在文件级进行镜像，而镜像在磁盘级。镜像意味着保留文件每个区域的冗余副本或镜像副本，以帮助避免因磁盘故障导致的数据丢失。每个文件盘区的镜像副本始终保留在与原始副本不同的磁盘上。如果磁盘发生故障，则Oracle
ASM将继续访问受影响的文件，方法是访问磁盘组中正在运行的磁盘上的镜像副本。
Online storage reconfiguration and dynamic
rebalancing—When using Oracle ASM, you can add or remove disks from your disk storage
system while the database is operating. When you add a disk to a disk group, Oracle ASM automatically redistributes the data so that it is evenly spread across all disks in the disk group, including the new disk. The process of redistributing data so that
it is also spread across the newly added disks is known as rebalancing.
It is done in the background and with minimal impact to database performance.
联机存储重新配置和动态重新平衡 -
使用Oracle ASM时，可以在数据库运行时从磁盘存储系统添加或移除磁盘。将磁盘添加到磁盘组时，Oracle ASM会自动重新分配数据，以便它均匀分布在磁盘组中的所有磁盘上，包括新磁盘。重新分配数据以便它也分布在新添加的磁盘上的过程称为重新平衡。它在后台完成，对数据库性能影响最小。

Managed file creation and deletion—Oracle
ASM further reduces administration tasks by enabling files stored in Oracle ASM disk groups to be managed by Oracle Database. Oracle ASM automatically assigns file names when files are created, and automatically deletes files when they are no longer needed
by the database.
       管理文件的创建和删除 -Oracle
ASM通过使存储在Oracle ASM磁盘组文件由Oracle数据库进行管理，进一步减少了管理任务。Oracle ASM创建文件时自动分配文件名，并在文件不再需要时自动删除文件。
Oracle Automatic Storage Management Cluster
File System (Oracle ACFS) is a new multi-platform, scalable file system, and storage management technology that extends Oracle ASM functionality to support customer files maintained outside of the Oracle database. Files supported by Oracle ACFS include database
and application executables, trace files, alert logs, application reports, BFILEs, and configuration files. Oracle ACFS leverages Oracle ASM functionality to provide dynamic file system resizing, striping, and mirroring.
Oracle自动存储管理集群文件系统（Oracle ACFS）是一种新的多平台，可扩展的文件系统和存储管理技术，可扩展Oracle
ASM功能以支持在Oracle数据库之外维护的客户文件。Oracle ACFS支持的文件包括数据库和应用程序可执行文件，跟踪文件，警报日志，应用程序报告，BFILE和配置文件。Oracle
ACFS利用Oracle ASM功能提供动态文件系统大小调整，条带化和镜像。
Oracle ASM is implemented as a special kind
of Oracle instance, with its own System Global Area and background processes. The Oracle ASM instance is tightly integrated with Oracle Clusterware and Oracle Database. Every server running one or more database instances that use Oracle ASM for storage has
an Oracle ASM instance. In an Oracle RAC environment,
there is one Oracle ASM instance for each node, and the Oracle ASM instances communicate with each other on a peer-to-peer basis. Only one Oracle ASM instance is supported on a node, but you can have multiple database instances that use Oracle ASM residing
on the same node. Figure
1-2, "Oracle Instances and Oracle ASM Storage" shows the storage configuration
commonly used for a 2-node Oracle RAC database.
Oracle ASM作为一种特殊的Oracle实例继承，具有自己的系统全局区域和后台进程。Oracle
ASM实例与Oracle Clusterware和Oracle Database紧密集成。每个运行一个或多个使用Oracle ASM进行存储的数据库实例的服务器都有一个Oracle ASM实例。在Oracle
RAC环境中，每个节点都有一个Oracle ASM实例，并且Oracle ASM实例在对等基础上相互通信。节点上仅支持一个Oracle ASM实例，但可以有多个使用驻留在同一节点上的Oracle
ASM的数据库实例。图1-2“Oracle实例和Oracle
ASM存储”显示了通常用于双节点Oracle RAC数据库的存储配置。
图1-2
Oracle实例和Oracle ASM存储



Oracle recommends that you use Oracle ASM for
your Oracle Clusterware files and Oracle RAC datafiles, instead of raw devices or the operating system file system. Oracle databases can use both Oracle ASM files and non-Oracle ASM files. You can also create a file system using Oracle ACFS to store your database
Oracle Home and any other external (non-database) files in the cluster.
Oracle建议您将Oracle
ASM用于Oracle Clusterware文件和Oracle RAC数据文件，而不是原始设备或操作系统文件系统。Oracle数据库可以同时使用Oracle ASM文件和非Oracle
ASM文件。您还可以使用Oracle ACFS创建文件系统，以将数据库Oracle Home和任何其他外部（非数据库）文件存储在群集中。