16.1.5. Restart Controls

The properties of this category control the creation of Restart Points and enable you to manage the files that the solver writes for each restart point. See the Solution Restarts section for more information about the restart capability and how it relates to Restart Points.

The properties of the Restart Controls category include:

PropertyDescription

Generate Restart Points

Enables the creation of restart points. Options include:

  • Program Controlled: Instructs the program to select restart point generation settings for you. This setting is equivalent to setting the Load Step and the Substep properties below to Last.

  • Manual: Enables access to the detailed settings for restart point generation.

  • Off: Restricts any new restart points from being created.

Load Step

This property enables you to specify the load step used to create restart points. Options include Last, All (default), and Specify[a].

The All option obtains restart points for all load steps. The Last option to obtains a restart point in the last load step only. And the Specify option enables you to enter the desired Load Step value in the Load Step Number property in order to generate restart points for the specific load step.

Note:  Do not restart an analysis from the end of a load step and then select the Specify option to save the restart points for the following load step. For example, do not restart an analysis from the end of a load step 2 and set the Specify option to Load Step 3.

Substep

Specifies how often the restart points are created within a load step. Options include:

  • Last (default): Write the file for the last substep of the load step only.

  • All: Write the files for all substeps of the load step.

  • Specified Recurrence Rate: Enter a number N, in the Value field, to generate restart points for a specified number of substeps per load step.

  • Equally Spaced Points: Enter a number N, in the Value field, to generate restart points at equally spaced time intervals within a load step.


    Note:  The Equally Spaced Points value is ignored for the remeshing database files (.rdnn[b]) created during SMART Crack Growth associated remeshing of a Static Structural analysis.


Maximum Points to Save Per Step

Specifies the maximum number of files to save for the load step. Choose one of the following options:

An entry of 0 specifies the option All. The maximum number of restart files for one run is 999. If this number is reached before the analysis is complete, the analysis continues but the application no longer writes any files. Enter a positive number to specify the maximum number of files to keep for each load step. When the maximum number has been written for each load step, the first file of that load step will be overwritten for subsequent substeps.

Exception

If your analysis includes a Nonlinear Adaptive Region or Geometry Based Adaptivity object, the application will begin overwriting restart files, starting with the oldest, once the total number of restart files reaches the maximum limit of 999.

Note:  If you want to interrupt the solution in a linear transient analysis, by default, the interrupt will be at load step boundaries only (as opposed to nonlinear analyses where interrupts occur at substeps). However, if you want to interrupt a solution to a linear transient analysis on a substep basis, set the following: Generate Restart Controls = Manual, Load Step = All, Substep = All, and Maximum Points to Save Per Step = 1. These settings allow you to accomplish the interrupt on a substep basis without filling up your disk with restart files.

Maximum Total Files to Save

This property enables you to specify the maximum total number of restart files the application can save during a restart analysis. Displayed when the Generate Restart Points property is set to Manual and the Step and Substep properties are set to any option other than Last.

An entry of 0 specifies the option All. The maximum number of restart files (*.xnnn) that can be saved is 999. The maximum number of remeshing database files (*.rdnn) for a restart analysis that includes a Nonlinear Adaptive Region, Geometry Based Adaptivity, or a SMART Crack Growth object, is 99. To specify a value in the Maximum Total Files to Save property, you must set the Maximum Points to Save Per Step property to All.

When set to All, if the model includes a Nonlinear Adaptive Region or Geometry Based Adaptivity object, the application begins overwriting restart files once the default maximum, 999 for *.xnnn files and 99 for *rdnn files, is reached. If the model includes a SMART Crack Growth object, the application begins overwriting the files once the maximum restart files (*.xnnn) and remeshing files (*.rdnn) exceed 99 files, respectively. In all other cases, the analysis continues, but no additional restart files are written.

Enter a positive number to specify the maximum total number of restart files to save. When the number of files exceeds the specified maximum number, the application resets the file numbering to 1 and continues writing restart (*.xnnn) and remeshing database (*rdnn) files. It retains the newest files and overwrites the oldest ones. The specified value applies to all subsequent load steps.

Note:  This property limits maximum total files for both the restart (*.xnnn) and remeshing database (*.rdnn) files when your analysis includes a SMART Crack Growth object. In all other cases, it just specifies the maximum total number of restart files.

Retain Files After Full Solve

When restart points are requested, the necessary restart files (rdb/rXXX/rdnn[b]) are always retained for an incomplete solve due to a convergence failure or user request. However, when the solve completes successfully, you have the option to request to either keep the restart points by setting this field to Yes, or to delete them by setting this field to No. You can control this setting here in the Details pane of the Analysis Settings object, or under Tools> Options in the Analysis Settings and Solution preferences list. The setting in the Details pane overrides the preference setting.

Note:   Retain Files After Full Solve has interactions with other controls. Under the Analysis Data Management category, setting the Future Analysis property to Prestressed forces the restart files to be retained. Similarly, setting the Delete Unneeded Files property to No implies that restart files are to be retained.

Combine Restart Files

This property enables you to select whether the multi-frame restart files will be automatically combined after the solution. Setting this property to Yes, prior to initiating a solve, enables you to restart your analysis with a different core count of processors. Options include:

  • Program Controlled (default): this option does not send any commands to the solver. It uses the Mechanical APDL solver default setting (No).

  • Yes: this option issues the command DMPOPTION, RNNN, YES. This is the required setting if you wish to combine result files in a downstream system.

  • No: this option issues the command DMPOPTION, RNNN, NO.


Note:  The Combine Restart Files property requires significant processing time if there is a large number of restart files to combine.


[a] Not supported for Coupled Field Static analyses.

[b] This is a remeshing database file that is generated during Nonlinear Adaptivity analyses and SMART Crack Growth analyses.