Technical White Paper

Transcription

1 Technical White Paper On Implementing IBM InfoSphere Change Data Capture for Sybase with a Remote Database Server Awajeet Kumar Arya(awajarya@in.ibm.com)

2 CONTENTS Trademarks...03 Introduction...04 Overview...04 Log Reading Connecting Remote Database through Sybase OCS Create instance with Remote Database References...15

3 Trademarks IBM and InfoSphere are trademarks of International Business Machines Corporation in the United States, other countries, or both. Java, JDBC and all Java-based trademarks are trademarks of Oracle Corporation. in the United States, other countries, or both. Other company, product, or service names may be trademarks or service marks of others.

4 Introduction Occasionally, questions arise about the use on the support of Remote Sybase with IBM InfoSphere Change Data Capture for Sybase. This paper provides the detailed documentation to configure the IBM InfoSphere Change Data Capture (CDC) for Sybase with a remote database server to capture streaming data changes from source to target. The paper provides step-by-step instruction to setup CDC instance with a remote Sybase instance in Unix platform Overview The following scenario describes how IBM InfoSphere Change Data Capture allows you to replicate data between a source database and a target database using IBM InfoSphere Change Data Capture (CDC) technology by streaming data changes into target databases. Figure 1 shows the architecture of CDC It is important to understand the flow and working mechanism of Infosphere CDC described here. It will be easier to derive the architecture of remote database support for Sybase.

5 Log Reading Traditional Configuration for Log Reading: The following diagram demonstrates the traditional configuration for Log Reading of Infosphere Change Data Capture (CDC) for Sybase with respect to Sybase. Figure 2 shows the traditional configuration for Log Reading CDC Capture processes the changes by asynchronously reading from the database recovery logs. Depending on the source database (Production DB), InfoSphere Change Data Capture might read the log files directly or it might use an API to read data from the log. In many cases, the data models of the source and target will not be the same. InfoSphere Change Data Capture can apply transformations to the data while it is in flight between source and target. After transformations, the changes are applied through CDC Apply to the target database. Changes are applied by executing SQL statements against the appropriate target tables.

6 Configuration for Remote Log Reading As a source, for remote log reading, InfoSphere CDC Sybase must be installed on a remote machine(secondary Server) with the same endian as the Sybase database server(production DB). OS has to be the same - which guarantees endianness. The remote machine where CDC is installed must have Sybase OCS installed in order to connect to Sybase ASE, this is required in order to query the Sybase system tables for information about the online transaction logs and also to access CDC metadata. The online and backup logs must be accessible via a SAN/shared mount point on the remote machine and the and have the same absolute path to logs as if CDC were installed on the database server otherwise CDC cannot find the logs. CDC user requires only read access to online logs and backup logs. As a target, for remote apply, InfoSphere CDC Sybase should be installed on a remote machine with the same endianness only if you require Refresh functionality via FastLoad. If you do not require FastLoad Refresh, then the remote machine can be on a different endian platform since the apply will be through JDBC. Apart from this, we need Sybase OCS installed in order to access Sybase to apply the data as well as CDC metadata in remote target machine. Figure 3 shows the concept of Remote Log Reading

7 Connecting Remote Database through Sybase OCS How we can connect to Remote Database through Sybase OCS? We can connect to Remote Database with the help of client configuration file of Sybase OCS. The configuration file is usually named as interfaces, or sql.ini, depending on the operating system. Set up the client configuration file by using the utility that comes with the Sybase Open Client software. This file is created in the $SYBASE directory on Unix. The name of the file is interfaces. An interfaces file contains network information about all servers on your network, including Adaptive Server, Backup Server, and XP Server, plus any other server applications such as Monitor Server, Replication Server, and any other Open Server applications. The network information in the file includes the server name, network name or address of the host machine, and the port, object, or socket number (depending on the network protocol) on which the server listens for queries. Each entry in an interfaces file can contain two types of lines: Master lines, which are used by server applications to listen for queries over the network. This information is called a listener service. Query lines, which are used by client applications to connect to servers over the network. This information is called a query service. The network information contained in the master and query lines for a server is identical because a server listens for connection requests on the same port that clients use to request connections. A server needs both master and query lines in its interfaces file, since servers sometimes act as clients to other servers. A client s interfaces file does not need a master line. It functions correctly with only a query line. Edit interfaces file (can be found inside installation directory of Sybase) and provide the network information in prescribed format.

8 Figure 4-shows the contents of interfaces file in Unix The interfaces file is usually named sql.ini on Windows operating system under %SY- BASE%\ini directory. Contents will be of sql.ini same as interfaces file of Unix.

9 Create Instance with Remote Database Create an instance of IBM InfoSphere Change Data Capture for Sybase with Remote Database. To add an instance of IBM InfoSphere Change Data Capture for Sybase, bring up IBM InfoSphere Change Data Capture Configuration Tool by executing dmconfigurets. You can find dmconfigurets under the bin folder of installation directory. Figure 5 shows the launching screen of dmconfigurets for the first instance Click OK here to create new instance. Provide required information like instance name, port number, Staging disk store quota, bit version, Sybase directory, SYBASE_OCS and Sybase Server and so on. Provide valid credentials to retrieve the database. Select required database. Database port will be default one.

10 Figure 6 Shows the various configuration options Here, select required metadata schema where the CDC Metadata will be created.

11 Figure 7 shows the list of available schemas Click OK after selecting desired schema.

12 Figure 8 shows the screen filled with all necessary details. Provide valid Archive Path. If you will not provide Archive Path then it will work as a target only. Essentially, the online transaction log and archive logs of the remote database machine must be accessible by the System where InfoSphere CDC is installed. The path to the online and backup log on the CDC machine must be the same as the path on the server. The online and backup logs must be accessible via a SAN/shared mount point on the remote machine where InfoSphere CDC is installed and have the same absolute path to logs as if InfoSphere CDC were installed on the database server otherwise InfoSphere CDC cannot find the logs. Now, click on OK to create new instance.

13 Figure 9 shows the status of creating instance.

14 Figure 11- confirms the instance creation. Click on yes to start the instance.

15 Figure 12 List all the instances and their status. References