NWChem Frequently Asked Questions

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# NWChem FAQ ## IBM SP What is the target for running NWChem on IBM SPs? I have a lapi_init error. How do I fix this problem? I have a load error when trying to run NWChem. How do I fix this problem? Thread scheduling policy change from AIX 4.3 to 4.3.3 which effects performance. How do I use more than 2 GB of disk space? What is the target for running NWChem on IBM SPs? The right target is
    LAPI
IBM binaries are not going to work on IBM SP systems. For further details, have a look at the Users's manual Running on an IBM SP. I have a lapi_init error. How do I fix this problem? If you get a message similar to:
       0: lapi_init failed 419(1a3)
     system message: Operation not permitted.
     ERRIR:  0031-250  task 0: terminated
you need to set the environment variable MP_MSG_API. You can either do this in your environment:
     setenv MP_MSG_API lapi
or you can set it in your LoadLeveller script:
     # @ network.lapi = css0, not_shared, US
The LoadLeveller method is preferred since it sets several other useful variables. NOTE: If you are using SMP nodes (i.e. more than one processor per node), change the "not_shared" to "shared". I have a load error when trying to run NWChem. How do I fix this problem? If you get a message similar to:
     exec(): 0509-036 Cannot load program /usr/local/NWChem/bin/nwchem because of the
      following errors:
             0509-023 Symbol kaio_rdwr in /usr/lpp/ppe.poe/lib/libc.a is not defined.
             0509-023 Symbol listio in /usr/lpp/ppe.poe/lib/libc.a is not defined.
             0509-023 Symbol acancel in /usr/lpp/ppe.poe/lib/libc.a is not defined.
             0509-023 Symbol iosuspend in /usr/lpp/ppe.poe/lib/libc.a is not defined.
             0509-022 Cannot load library libc.a[aio.o].
             0509-026 System error: Cannot run a file that does not have a valid format.
The problem is that Asynchronous I/O is not turned on for your system. There are two possible solutions. The first and best solution is to have the system administrator turn on Asynchronous I/O on all of the nodes. This can be done by: Enter smit Go to "Devices" Go to "Asynchronous I/O" Go to "Change / Show Characteristics of Asynchronous I/O" Change "State of fast path" to "enable" Make sure "STATE to be configured at system restart" is set to "available" Exit smit The nodes will need to be rebooted for the change to take effect. The second solution is to compile GA without Asynchronous I/O turned on. This WILL slow down the performance of NWChem. cd $NWCHEM_TOP/src/tools/pario make TARGET=LAPI clean make TARGET=LAPI CC="cc -DNOAIO" LARGE_FILES=y cd $NWCHEM_TOP/src make link Thread scheduling policy change from AIX 4.3 to 4.3.3 which effects performance. The default thread scheduling policy changed from AIX version 4.3 to 4.3.3 which effects MPI and LAPI programs that rely on switch packet arrival interrupts (such as NWChem). This directly effects the performance of NWChem. To change the default, you need to set the environment variable RT_GRQ. You can either do this in your environment:
     setenv RT_GRQ ON
or you can set it in your LoadLeveller script:
     # @ environment      =    RT_GRQ=ON
Note that you may have other variables to set with the environment line. Just add the variable onto the existing line using a semi-colon as a separator. For example:
     # @ environment      =    COPY_ALL; MP_INFOLEVEL=3; MP_PULSE=0;
     MP_SINGLE_THREAD=yes; MP_WAIT_MODE=yield; RT_GRQ=ON; restart=no
How do I use more than 2 GB of disk space? During the compilation, the environment variable LARGE_FILES needs to be set (i.e. setenv LARGE_FILES TRUE). Also, you should make sure that the file sizes on your system are not limited to 2 GB (type "limit" and check the output). If the sizes are limited, ask your system adminitrator to change the limit for you. NWChem | Capabilities | Platforms | Download | User's Manual | Programmer's Manual | Release Notes | FAQ Known Bugs | Support | Tutorial | Contributors | Benchmarks | Search | Mol Sci. Soft. Group | Citation Contact: NWChem Support Updated: February 22, 2005