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Changeset 10505 – NEMO

Changeset 10505

2019-01-11T15:32:07+01:00 (5 years ago)

ticket #2204 updated documentation

1 edited


  • NEMO/branches/2019/dev_r10503_XIOS_RW_doc/doc/latex/NEMO/subfiles/chap_DIA.tex

    r10442 r10505  
    115115Note that for smaller configurations, the rebuilding phase can be avoided, 
    116116even without a parallel-enabled NetCDF4 library, simply by employing only one dedicated I/O server. 
     118\subsection{XIOS: Reading and writing restart file} 
     120XIOS may be used to read single file restart produced by NEMO. Currently only the variables written to  
     121file \textit{numror} can be handled by XIOS. To activate restart reading using XIOS \textit{ln\_xios\_read}  
     122must be set to \textit{.true.}.  
     123in \textit{namelist\_cfg}. This setting will be ignored when multiple restart files are present, and default NEMO  
     124functionality will be used for reading. There is no need to change iodef.xml file to use XIOS to read  
     125restart, all definitions are done within the NEMO code. For high resolution configuration, however,  
     126there may be a need to add the following line in iodef.xml (xios context): 
     128 <variable id="recv\_field\_timeout"        type="double">1800</variable>.  
     130This variable sets timeout for reading.  
     132If XIOS is to be used to read restart from file generated with an earlier NEMO version (3.6 for instance), 
     133dimension \textit{z} defined in restart file must be renamed to \textit{nav\_lev}. 
     135XIOS can also be used to write NEMO restart. A namelist parameter \textit{nn\_wxios} is used to determine the  
     136type of restart NEMO will write. If it is set to 0, default NEMO functionality will be used - each  
     137processor writes its own restart file; if it is set to 1 XIOS will write restart into a single file;  
     138for \textit{nn\_wxios = 2} the restart will be written by XIOS into multiple files, one for each XIOS server.  
     139Note, however, that \textbf{NEMO will not read restart generated by XIOS when \textit{nn\_wxios = 2}}. The restart will  
     140have to be rebuild before continuing the run. This option aims to reduce number of restart files generated by NEMO only,  
     141and may be useful when there is a need to change number of processors used to run simulation.  
     143If an additional variable must be written to a restart file, the following steps are needed: 
     146add variable name to a list of restart variables (in subroutine \textit{iom\_set\_rst\_vars}, iom.F90) and  
     147define correct grid for the variable (grid\_N\_3D - 3D variable, grid\_N - 2D variable, grid\_vector -  
     1481D variable, grid\_scalar - scalar), 
     150add variable to the list of fields written by restart.  This can be done either in subroutine  
     151\textit{iom\_set\_rstw\_core} (iom.F90) or by calling  \textit{iom\_set\_rstw\_active} (iom.F90) with the name of a variable  
     152as an argument. This convention follows approach for writing restart using iom, where variables are  
     153written either by \textit{rst\_write} or by calling \textit{iom\_rstput} from individual routines. 
     157An older versions of XIOS do not support reading functionality. It's recommended to use at least XIOS2@1451. 
    118160\subsection{XIOS: XML Inputs-Outputs Server} 
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