The "Familied" Nature of Database Files

The familied nature of database files.

All of the database files above use a family structure. There is always a "root" member, which may have between 1 and 999 "children". This is done to keep file sizes down: there are many advantages to having a few moderately big files instead of one huge one.

The maximum size of a family member is set when Ansys LS-DYNA is run, and a new "child" member is opened if writing the current block of information would cause the current member to spill over this limit.

By default 7Mbytes is used (in single precision), corresponding to 1835008 words of data, but it is possible to change this when the Ansys LS-DYNA job is submitted via the X= parameter on the DYNA submission line, or via the Shell. However very large analyses often use a larger family size in order to stop results states spilling over into multiple family members.

By default D3PLOT determines the file family size automatically (by taking the greater size of the first two members of a family, and rounding up to the nearest Mbyte). You can over-ride this by setting an explicit size (see The FILE > popup menu options ) but this should rarely, if ever, be necessary.

Note: Previous versions of D3PLOT used signed 32 bit integers to represent disk addresses, which limited total database size to 2 ³¹ words, or 2GWords.

D3PLOT 8.0 onwards uses 64 bit integers to represent disk addresses, even on 32 bit machines, which means that it can access disk addresses up to 2 ⁶³ words, or 9e18 words.

Ansys LS-DYNA from approximately 2002 (~LS960) onwards no longer adheres to the maximum database size logic for .ptf files for larger models. If the state is too big to fit into a single family member it is allowed to increase in size in order to contain the state. D3PLOT handles this automatically.