Oracle 11gR2 rac 的各項服務說明

   安裝結束後，會産生一些背景程序來確定叢集正常工作并能夠與外部通訊。其中的一些有序linux平台的要求需要以root使用者權限來啟動。比如，網絡配置的改動就需要更高的權限。其他背景程序将以grid軟體所在系統使用者的權限來運作。下面的表格介紹主要的一

些背景程序

背景程序

說明

Oracle高可用服務 (OHAS)

OHAS是伺服器啟動後打開的第一個Grid Infrastructure元件。它被配置為以init(1)打開，并負

責生成agent程序。

Oracle Agent

Grid Infrastructure使用兩個oracle代理程序。第一個，概括起來說，負責打開一些需要通路

OCR和VOTING檔案的資源。它由OHAS建立。

第二個代理程序由CRSD建立，負責打開所有不需要root權限來通路的資源。這個程序以

Grid Infrastructure所屬使用者的權限運作，并且負責在RAC11.1中racg所做的工作。

Oracle Root Agent

和 Oracle 代理程序類似，有兩個Root 代理程序被建立。 最初的代理程序由OHAS引發，它

為linux系統中需要更高權限的資源提供初始化。建立的主要背景程序是CSSD和CRSD。反

過來，CRSD将觸發另一個root代理。這個代理将打開需要root權限、主要和網絡相關的資源

叢集就緒服務程序

(CRSD)

叢集軟體的背景主要程序，使用oracle叢集注冊資訊來管理叢集中的資源

叢集同步服務程序

(CSSD)

管理叢集的配置和節點成員

Oracle程序監控

(OPROCD)

oprocd在11.1版本中負責 I/O 隔離。它是在10.2.0.4更新檔集中為linux系統引入的。在這個更新檔

集以前，核心hangcheck-timer子產品來做類似的任務。有趣的是，oprocd以前常被用在非

linux平台中。Grid Infrastructure用cssdagent程序來替換了oprocd程序。

事件管理器(EVM)

EVM負責釋出Grid Infrastructure建立的事件

叢集時間同步服務(CTSS)

CTSS服務是一個可選項，通過網絡時間協定伺服器為叢集提供時間同步，這個時間同步對

RAC很重要。它可以運作在兩種模式下：觀望或者活動。當NTP被激活的時候，它運作在

觀察模式，若沒有啟動NTP，它将根據主節點同步所有節點的時間。

Oracle警告服務(ONS)

負責通過快速應用架構釋出事件的主要背景程序。

Oracle Clusterware consists of two separate stacks: an upper stack anchored by the Cluster Ready Services (CRS) daemon (<code>crsd</code>) and a lower stack anchored by the Oracle High Availability Services daemon (<code>ohasd</code>).

These two stacks have several processes that facilitate cluster operations. The following sections describe these stacks in more detail:

oracle 叢集包含兩個技術棧：上層棧由CRS服務控制，下層棧由OHAS控制。這兩個棧分别有幾個processes來完成叢集服務。下面分别介紹之。

The list in this section describes the processes that comprise CRS. The list includes components that are processes on Linux and UNIX operating systems, or services on Windows.

Cluster Ready Services (CRS): The primary program for managing high availability operations in a cluster.

The CRS daemon <code>(crsd</code>) manages cluster resources based on the configuration information that is stored in OCR for

each resource. This includes start, stop, monitor, and failover operations. The <code>crsd</code> process generates events when the status of a resource changes. When you have Oracle

RAC installed, the <code>crsd</code> process monitors the Oracle database instance, listener, and so on, and automatically restarts these components when a failure occurs.（叢集就緒服務管理叢集資源，這些資源是存儲在ocr裡的配置資訊。包括對這些資源啟停，監控等操作。當資源的狀态改變的時候，crsd程序生産事件。）

Cluster Synchronization Services (CSS): Manages the cluster configuration by controlling which nodes are members of the cluster and by notifying members when a

node joins or leaves the cluster. If you are using certified third-party clusterware, then CSS processes interface with your clusterware to manage node membership information.

The <code>cssdagent</code> process monitors the cluster and provides I/O fencing. This service formerly was provided by Oracle

Process Monitor Daemon (<code>oprocd</code>), also known as <code>OraFenceService</code> on Windows.

A <code>cssdagent</code> failure may result in Oracle Clusterware restarting the node.（cssdagent程序監控叢集并且提供IO隔離。crss服務主要是提供叢集同步，檢查節點數量，增加減少節點）

Oracle ASM: Provides disk management for Oracle Clusterware and Oracle Database.(提供叢集和資料庫的磁盤管理服務)

Cluster Time Synchronization Service (CTSS): Provides time management in a cluster for Oracle Clusterware.（CTSS服務是一個可選項，通過網絡時間協定伺服器為叢集提供時間同步，這個時間同步對RAC很重要。它可以運作在兩種模式下：觀望或者活動。當NTP被激活的時候，它運作在觀察模式，若沒有啟動NTP，它将根據主節點同步所有節點的時間。）

Event Management (EVM): A background process that publishes events that Oracle Clusterware creates.（釋出叢集産生的事件的程序——EVM負責釋出Grid Infrastructure建立的事件）

Oracle Notification Service (ONS): A publish and subscribe service for communicating Fast Application Notification (FAN) events.（負責通過快速應用架構釋出事件的主要背景程序。）

Oracle Agent (oraagent): Extends clusterware to support Oracle-specific requirements and complex resources. This process runs server callout scripts when FAN events occur. This process

was known as RACG in Oracle Clusterware 11g release 1 (11.1).

Oracle Root Agent (orarootagent): A specialized <code>oraagent</code> process that helps <code>crsd</code> manage resources owned by <code>root</code>,

such as the network, and the Grid virtual IP address.

The Cluster Synchronization Service (CSS), Event Management (EVM), and Oracle Notification Services (ONS) components communicate with other cluster component layers on other nodes in the same cluster database environment. These components are also the main

communication links between Oracle Database, applications, and the Oracle Clusterware high availability components. In addition, these background processes monitor and manage database operations.

This section describes the processes that comprise the Oracle High Availability Services stack. The list includes components that are processes on Linux and UNIX operating systems, or services on Windows.

Cluster Logger Service (<code>ologgerd</code>):

Receives information from all the nodes in the cluster and persists in a CHM repository-based database. This service runs on only two nodes in a cluster.

System Monitor Service (<code>osysmond</code>):

The monitoring and operating system metric collection service that sends the data to the cluster logger service. This service runs on every node in a cluster.

Grid Plug and Play (GPNPD): Provides access to the Grid Plug and Play profile, and coordinates updates to the profile among the nodes of the cluster to ensure that all of the nodes

have the most recent profile.

Grid Interprocess Communication (GIPC): A support daemon that enables Redundant Interconnect Usage.

Multicast Domain Name Service (mDNS): Used by Grid Plug and Play to locate profiles in the cluster, as well as by GNS to perform name resolution. The mDNS process is a background process

on Linux and UNIX and on Windows.

Oracle Grid Naming Service (GNS): Handles requests sent by external DNS servers, performing name resolution for names defined by the cluster.

Table 1-1 lists the processes and services associated with Oracle Clusterware components. In Table 1-1, if a UNIX or a Linux system process has

an (r) beside it, then the process runs as the <code>root</code> user.