Operating System Requirements

Memory Requirements

All Platforms

The amount of memory that is required for Oracle GoldenGate depends on the amount of data being processed, the number of Oracle GoldenGate processes running, the amount of RAM available to Oracle GoldenGate, and the amount of disk space that is available to Oracle GoldenGate for storing pages of RAM temporarily on disk when the operating system needs to free up RAM (typically when a low watermark is reached). This temporary storage of RAM to disk is commonly known as swapping or paging (herein referred to as swapping). Depending on the platform, the term swap space can be a swap partition, a swap file, a page file (Windows) or a shared memory segment (IBM for i).

Modern servers have sufficient RAM combined with sufficient swap space and memory management systems to run Oracle GoldenGate. However, increasing the amount of RAM available to Oracle GoldenGate may significantly improve its performance, as well as that of the system in general.

Typical Oracle GoldenGate installations provide RAM in multiples of gigabytes to prevent excessive swapping of RAM pages to disk. The more contention there is for RAM the more swap space that is used.

Excessive swapping to disk causes performance issues for the Extract process in particular, because it must store data from each open transaction until a commit record is received. If Oracle GoldenGate runs on the same system as the database, then the amount of RAM that is available becomes critical to the performance of both.

RAM and swap usage are controlled by the operating system, not the Oracle GoldenGate processes. The Oracle GoldenGate cache manager takes advantage of the memory management functions of the operating system to ensure that the Oracle GoldenGate processes work in a sustained and efficient manner. In most cases, users need not change the default Oracle GoldenGate memory management configuration.

For more information about evaluating Oracle GoldenGate memory requirements, see the CACHEMGR parameter in the Parameters and Functions Reference for Oracle GoldenGate.

Db2 z/OS: Memory Requirements

Oracle GoldenGate requires the following memory resources on the Oracle GoldenGate remote system and the database host system. For the memory resources required on a remote system, see the All Platforms section above.

On the Db2 host system

Allocate approximately 10-50 MB of virtual memory for each Oracle GoldenGate log reader, oggreadb, that is invoked depending on the size of the log buffer. There is one invocation per Extract process on the remote system. To adjust the maximum log buffer size, use the TRANLOGOPTIONS BUFSIZE parameter in the Extract parameter file.

When setting up the Workload Manager (WLM) environment for the Extract log read components, it is recommended to set NUMTCB in the range of 10-40 depending on your environment. This is based on the IBM general guidelines available here:

https://www.ibm.com/docs/en/idr/11.4.0?topic=install-setting-numtcb

Disk Requirements

Disk Requirements for Oracle GoldenGate Installation Files

This section lists the disk space requirements for Oracle GoldenGate and specific disk space considerations for Db2 z/OS database.

The disk space requirements for an Oracle GoldenGate installation vary based on your operating system and database. Ensure that you have adequate disk space for the downloaded file, expanded files, and installed files, which can be up to 2GB.

Temporary Disk Requirements

When total cached transaction data exceeds the CACHESIZE setting of the CACHEMGR parameter, Extract begins writing cache data to temporary files located in the Oracle GoldenGate installation directory. For Microservices Architecture, it is the /var/temp folder for that deployment.

The cache manager assumes that all of the free space on the file system is available. These directories can fill up quickly if there are many transactions with large transaction sizes. To prevent I/O contention and possible disk-related Extract failures, dedicate a disk to this directory. You can assign a name to this directory with the CACHEDIRECTORY option of the CACHEMGR parameter.

Note:

CACHEMGR is an internally self-configuring and self-adjusting parameter. It is rare that this parameter requires modification. Doing so unnecessarily may result in performance degradation. It is best to acquire empirical evidence before opening an Oracle Service Request and consulting with Oracle Support.

It is typically more efficient for the operating system to swap to disk than it is for Extract to write temporary files. The default CACHESIZE setting assumes this. Thus, there should be sufficient disk space to account for this, because only after the value for CACHESIZE is exceeded will Extract write transaction cached data to temporary files in the file system name space. If multiple Extract processes are running on a system, the disk requirements can multiply. Oracle GoldenGate writes to disk when there is not enough memory to store an open transaction. Once the transaction has been committed or rolled back, committed data is written to trail files and the data are released from memory and Oracle GoldenGate no longer keeps track of that transaction. There are no minimum disk requirements because when transactions are committed after every single operation these transactions are never written to disk.

Note:

Oracle recommends that you do not change the CACHESIZE because performance can be adversely affected depending on your environment.

Other Disk Space Considerations

In addition to the disk space required for the files and binaries that are installed by Oracle GoldenGate, allow additional disk space to hold the Oracle GoldenGate trails. Trails can be created up to 2GB in size, with a default of 500MB. The space required depends upon the selected size of the trails, the amount of data being captured for replication, and how long the consumed trails are kept on the disk. The recommended minimum disk allocated for Trails may be computed as:

((transaction log size * 0.33) * number of log switches per day) * number of days to retain trails

Based on this equation, if the transaction logs are 1GB in size and there is an average of 10 log switches per day, it means that Oracle GoldenGate will capture 3.3GB data per day. To be able to retain trails for 7 days, the minimum amount of disk space needed to hold the trails is 23GB.

A trail is a set of self-aging files that contain the working data at rest and during processing. You may need more or less than this amount, because the space that is consumed by the trails depends on the volume of data that will be processed.

Network Requirements

The following network resources must be available to support Oracle GoldenGate:

Use the fastest network possible and install redundancies at all points of failure for optimal performance and reliability, especially in maintaining low latency on the target.
You can configure Oracle GoldenGate Microservices to use a reverse proxy. Oracle GoldenGate Microservices includes a script called ReverseProxySettings that generates configuration file for only the NGINX reverse proxy server.

See Configure Oracle GoldenGate Reverse Proxy with NGINX.
Configure the system to use both TCP and UDP services, including DNS. Oracle GoldenGate supports IPv4 and IPv6 and can operate in a system that supports one or both of these protocols.
Configure the network with the host names or IP addresses of all systems that will be hosting Oracle GoldenGate processes and to which Oracle GoldenGate will be connecting.
Oracle GoldenGate requires some unreserved and unrestricted TCP/IP network ports, the number of which depends on the number and types of processes in your configuration.
Keep a record of the ports that you assigned to Oracle GoldenGate processes. You specify them with parameters when configuring deployments for the Microservices Architecture.
Configure your firewalls to accept connections through the Oracle GoldenGate ports.

Operating System Privileges

The following are the privileges in the operating system that are required to install Oracle GoldenGate Microservices Architecture and to run the processes:

The user who installs Oracle GoldenGate must be granted read and write privileges on the Oracle GoldenGate software home directory.
To install on Windows, the user who installs Oracle GoldenGate must log in as an Administrator.
The user who configures deployments using the oggca.sh script and creates Oracle GoldenGate Extract and Replicat processes must have read, write, and delete privileges on files and subdirectories in the Oracle GoldenGate directory.
For Extract processes that read from transaction logs and backups, the user must have read access to the logs and backup files.
Oracle recommends that you dedicate a database user to Oracle GoldenGate Extract and Replicat processes. Sensitive information might be available to anyone who runs an Oracle GoldenGate processes, depending on how database authentication is configured.
For Db2 z/OS, the remote host requires privileges to use the chmod +rw command on the sub-directories in the Oracle GoldenGate product directory.

Windows Console Character Sets

The operating system and the command console must have the same character sets. Mismatches occur on Microsoft Windows systems, where the operating system is set to one character set, but the DOS command prompt uses a different, older DOS character set. Oracle GoldenGate uses the character set of the operating system to send information to the Admin Client command output. So, a non-matching console character set causes characters not to display correctly. You can set the character set of the console before opening an Admin Client session by using the following DOS command:

chcp codepagenumber

For example, chcp 437.

For a code page overview, see https://msdn.microsoft.com/en-us/library/windows/desktop/dd317752(v=vs.85).aspx and the list of code page identifiers https://msdn.microsoft.com/en-us/library/windows/desktop/dd317756(v=vs.85).aspx.