Porting linux application on cray machine

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SUMMARY

This discussion focuses on the challenges of porting an oceanic model from Ubuntu Linux to a Cray SV1 machine running the UNICOS operating system, specifically regarding the handling of unformatted Fortran files. The user encountered a "UNRECOVERABLE library error" related to an invalid block control word (BCW) when attempting to read unformatted files. The consensus is that unformatted files are non-portable across different architectures, particularly due to variations in word sizes and floating-point representations. It is recommended to use text format files for data exchange to avoid these compatibility issues.

PREREQUISITES
  • Understanding of Fortran I/O operations, particularly with unformatted files.
  • Familiarity with Cray SV1 architecture and the UNICOS operating system.
  • Knowledge of data representation differences between x86/x64 and Cray systems.
  • Experience with file handling and data migration techniques in high-performance computing environments.
NEXT STEPS
  • Research utilities for converting unformatted Fortran files to text format.
  • Learn about COS blocking and its implications for Fortran file I/O on Cray systems.
  • Explore the use of the assign(1) or asgcmd(1) commands for file specification in Fortran.
  • Investigate best practices for data migration between different computing architectures.
USEFUL FOR

This discussion is beneficial for developers and researchers working with Fortran applications on high-performance computing systems, particularly those transitioning code between different architectures like Cray and x86/x64 environments.

yairsuari
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I am trying to deploy my oceanic model currently runing on ubuntu linux and compiled with intel fortran on a cray sv1 machine with UNICOS operating system.
It actually went quite well until i tried to read unformatted files. i am using the following code to export the data to the new machine:
file_name=trim(datafolder)//'basin'
open(21,file=file_name,status='old',
+ form='unformatted',convert='little_endian')
read(21)h,alat,alon,dx,dy
read(21)fsm,dum,dvm
read(21) z,zz
close(21)
file_name='~/Documents/temp/phys/data/basin'
open(21,file=file_name,status='new',
+ form='unformatted',convert='cray')
write(21)h,alat,alon,dx,dy
write(21)fsm,dum,dvm
write(21) z,zz
close(21)
When i copy the produced file to the new machine and try running the model i get the following error massage:
lib-5026 ./a.out: UNRECOVERABLE library error
The COS blocked file contains an invalid BCW (block control word).
Encountered during a sequential unformatted READ from unit 21
Fortran unit 21 is connected to a sequential unformatted COS blocked file:
"/users/negev1/biu/ysuari/prog/bfm_3dcode/phys/data/basin"
Error initiated at line 225 in routine '_rdunf'.
Abort
Beginning of Traceback:
Interrupt at address 377677a in routine '_lwp_killm'.
Called from line 32 (address 374366a) in routine 'raise'.
Called from line 127 (address 302611d) in routine 'abort'.
Called from line 59 (address 704047a) in routine '_ferr'.
Called from line 225 (address 735714c) in routine '_rdunf'.
Called from line 357 (address 676525a) in routine '_xfer_iolist'.
Called from line 147 (address 742423c) in routine '_FRU'.
Called from line 6347 (address 110006b) in routine 'BASIN'.
Called from line 789 (address 2575a) in routine 'POM2K'.
Called from line 350 (address 324455c) in routine '$START$'.
End of Traceback.
IOT trap (core dumped)
the error is explained as:
The COS blocked file contains an invalid BCW (block control word).
A Fortran I/O or positioning operation or an FFIO() operation on a COS
blocked file encountered a BCW (block control word) that is not valid. The
file may not be a COS blocked file, or it may be corrupted.
Ensure that the file is COS blocked; if it is not, use the appropriate
specification on the assign(1) or asgcmd(1) command. If the file is
corrupted, re-create it if possible.
even after reading the section about the assign command this error massage is like Chinese to me.

does anyone know how the file migration should be done?

thanks yair
 
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just for the record i used formatted text files as suggested below:

Unformatted files are non-portable, especially between machines with different word sizes and floating-point representations. There may be utilities available to help with the conversion. Simply writing an unformatted file on an x-86 or x-64 PC and reading the file on an SV1, which AFAIK does not use IEEE floating-point, will not work.
 
Use a text format file to exchange data. On some machines, unformatted I/O means text files, on others it mean binary files. On IBM mainframes, it's some weird binary data that included offsets into memory, and on the old Fortran G compiler, reading text data with unformatted I/O sometimes read the data into the PSW's at low memory, crashing the computer (I had this happen twice before I realized it was my program crashing the system).
 

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