When you start an ABAQUS/CAE session, a cache is created in the scratch file directory. ABAQUS/CAE uses this cache for local data storage when you use a network ODB connector to read from a remote output database. The cache greatly increases the performance of the Visualization module in ABAQUS/CAE when accessing data from the remote output database.

ABAQUS/CAE allows the cache to grow to a size that is sufficient to contain all of the data in all of the open remote output databases. However, ABAQUS/CAE limits the cache size to 80% of the total free space in the directory. For example, if the scratch directory has 35 gigabytes of unused space, ABAQUS/CAE will allow the cache to grow to 28 gigabytes. Alternatively, you can limit the size of the cache using the nodb_cache_limit parameter in the ABAQUS environment file, abaqus_v6.env. You must set the nodb_cache_limit parameter to the number of megabytes to which the cache size will be limited. For example,

nodb_cache_limit=20000

will set the maximum cache size to 20 gigabytes. ABAQUS/CAE uses this cache space only as needed during a session, and the actual cache size may be significantly less than the limit you specified. The minimum value of nodb_cache_limit is 500, indicating that the cache size is limited to 500 megabytes. If you set the maximum cache size to be greater than the available free space, ABAQUS/CAE reduces it to a value that is equal to the available free space.

ABAQUS/CAE uses the cache to increase its performance when reading data from a remote output database. The speed at which data can be accessed over a network is significantly lower than the speed at which data can be accessed from a local disk drive. As a result, the performance of remote output databases will be significantly slower than the performance of a local output database. The cache reduces this performance difference by retaining data that have been transferred over the network, thereby reducing the need for data transfer over the network. However, if the cache is not large enough, ABAQUS/CAE will have to transfer more data over the network and performance will suffer.

In most cases you will not have to tune the size of the cache using the nodb_cache_limit parameter. However, you may have to reduce the size of the cache if it is consuming too much disk space and reducing the speed of other applications on your system. Similarly, you may have to increase the size of the cache if it is too small to support all of your remote output databases and the performance of ABAQUS/CAE is degraded. If you cannot increase the size of the cache, you should close some of your remote output databases.

If the desired cache size is larger than the space available in the scratch file directory, you can move the scratch file directory to a larger disk drive using the ABAQUS scratch environment file parameter. For more information, see “Using the ABAQUS environment settings,” Section 3.3.1 of the ABAQUS Analysis User's Manual, and “Managing memory and disk use in ABAQUS,” Section 3.4.1 of the ABAQUS Analysis User's Manual.