# RESTART_OUTPUT

Specifies parameters for outputting restart files.

AcuSolve Command

## Syntax

RESTART_OUTPUT {parameters}

## Qualifier

This command has no qualifier.

## Parameters

output_frequency or out_freq (integer) >=0 [=1000]
Time step frequency at which to output restart data. If zero, this option is ignored.
output_time_interval or out_intv (real) >=0 [=0]
Time frequency at which to output restart data. If zero, this option is ignored.
num_saved_states or save (integer) >=0 [=0]
Number of restart states to keep. If zero, all restart files are kept.

## Description

This command specifies the parameters for writing restart files to disk. For example,
RESTART_OUTPUT {
output_frequency     = 100
output_time_interval = 0
num_saved_states     = 2
}

writes a restart file to disk every 100 time steps as well as the last time step. Only the last two restart steps are kept. Once the third restart file is written to disk, the first restart file is removed to preserve disk space.

The restart files are tagged by their problem name, run ID, and time step. The RESTART command uses these tags to access the files.

If either output_frequency or output_time_interval is non-zero, a restart file will be written at the end of the run. If both are zero, no restart files are created.

Run times may not coincide with output_time_interval. In this case, at every time step which passes through a multiple of output_time_interval, restart data are output.

The num_saved_states parameter indicates the number of restart files to save. Once the (num_saved_states + 1)th restart file is written, the first one is removed. When running in parallel, once all files are written (in parallel), then the old ones are removed (in parallel).