These are the known restrictions in Compaq MPI Version 1.9:
In this release, the stdout and stderr streams from application processes are combined and are both delivered to stdout. There is no output on stderr.
When a debugger is used, dmpirun creates (and never deletes) a number of small files in /tmp. If you repeatedly debug large applications, you may need to delete these files to avoid filling /tmp.
The Fortran binding for MPI_ADDRESS specifies that addresses be returned as type INTEGER. This specification is insufficient, because INTEGERs are 32 bit, whereas addresses are 64 bit on Alpha systems.
In order to allow use of the MPI_ADDRESS call, this release uses INTEGER*8 as the return type. This does not affect the C binding, or its use in a C program.
MPI_REQUEST_FREE does not work properly when the request is not completed (the mpich portable code has the same problem).
MPI_CANCEL does not work (the MPICH portable code does not implement this).
A process that has called MPI_INIT may fail if it calls execl, execv, execle, execve, execlp, or execvp. The exec routine returns EWOULDBLOCK.
This problem can be avoided if the process calls fork, and calls the exec routine in the child process.
When a process that has called MPI_INIT forks, the child process sometimes loses some virtual memory resources. If an application uses multiple generations of processes (parent makes MPI calls then forks child, which makes MPI calls then forks, and so on), the application may run out of vm-mapentries. The number of vm-mapentries available to an application may be changed using the sysconfig(8) command.
A call to MPI_INIT that fails with an error reporting "no MEMORY CHANNEL installed" usually indicates that the MEMORY CHANNEL[TM] patch has not been installed.