LAM 7.0.5 Release Notes
Description: LAM Implementation of MPI
Keywords: MPI, LAM, parallel computing, beowulf, linux

| # LAM 7.0.5 Release Notes
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This page provides release notes for LAM targeted at LAM users. The bulk of the release notes for LAM/MPI 7.0.5 are in the Installation Guide and User's Guide. Both documents are also included in the `doc/` directory of every LAM/MPI tarball. ## Case-Insensitive Filesystems On systems with case-insensitive filesystems (such as Mac OS X with HFS+, or Linux with NTFS), the `mpicc` and `mpiCC` commands will both refer to the same executable. This obviously makes distinguishing between the `mpicc` and `mpiCC` wrapper compilers impossible. LAM will attempt to determine if you are building on a case-insensitive filesystem. If you are, the C++ wrapper compiler will be called `mpic++`. Otherwise, the C++ compiler will be called `mpiCC` (although `mpic++` will also be available). ## NFS-shared /tmp The LAM per-session directory may not work properly when hosted in an NFS directory, and may cause problems when running MPI programs and/or supplementary LAM run-time environment commands. If using a local filesystem is not possible (e.g., on diskless workstations), the use of `tmpfs` or `tinyfs` is recommended. LAM's session directory will not grow large; it contains a small amount of meta data as well as known endpoints for Unix sockets to allow LAM/MPI programs to contact the local LAM run-time environment daemon. ## AFS and tokens/permissoins AFS has some peculiarities, especially with file permissions when using `rsh`/`ssh`. Many sites tend to install the AFS `rsh` replacement that passes tokens to the remote machine as the default `rsh`. Similarly, most modern versions of `ssh` have the ability to pass AFS tokens. Hence, if you are using the rsh boot module with `recon` or `lamboot`, your AFS token will be passed to the remote LAM daemon automatically. If your site does not install the AFS replacement `rsh` as the default, consult the documentation on `with-rsh` to see how to set the path to the `rsh` that LAM will use. Once you use the replacement `rsh` or an AFS-capable `ssh`, you should get a token on the target node when using the rsh boot module (If you are using a different boot module, you may experience problems with obtaining AFS tokens on remote nodes.). This means that your LAM daemons are running with your AFS token, and you should be able to run any program that you wish, including those that are not `system:anyuser` accessible. You will even be able to write into AFS directories where you have write permission (as you would expect). Keep in mind, however, that AFS tokens have limited lives, and will eventually expire. This means that your LAM daemons (and user MPI programs) will lose their AFS permissions after some specified time unless you renew your token (with the `klog` command, for example) on the originating machine before the token runs out. This can play havoc with long-running MPI programs that periodically write out file results; if you lose your AFS token in the middle of a run, and your program tries to write out to a file, it will not have permission to, which may cause Bad Things to happen. If you need to run long MPI jobs with LAM on AFS, it is usually advisable to ask your AFS administrator to increase your default token life time to a large value, such as 2 weeks. ## Solaris and GM The gm RPI will fail to function properly on versions of Solaris older than Solaris 7.