Temporary Disk 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.
Parent topic: Disk Requirements