Disk Requirements
Disk space requirements vary based on the platform, database, and Oracle GoldenGate architecture to be installed.
Disk Requirements for Oracle GoldenGate Installation Files
The disk space requirements for a 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.
To determine the size of the Oracle GoldenGate download file, view the Size column before downloading your selected build from Oracle Software Delivery Cloud. The value shown is the size of the files in compressed form. The size of the expanded Oracle GoldenGate installation directory is significantly larger on disk.
Temporary Disc Requirements
dirtmp sub-directory of the Oracle GoldenGate installation
directory. When total cached transaction data exceeds the CACHESIZE
setting of the CACHEMGR parameter, Extract will begin writing cache
data to temporary files. The cache manager assumes that all of the free space on the
file system is available. This directory can fill up quickly if there is a large
transaction volume 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.
Important:
Oracle recommends that you do not change the
CACHESIZE because performance can be adversely effected
depending on your environment.
Other Disc 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.