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Filesystem Update May 2nd, 2008

Changes to RCF filesystems and how they affect users

May 2nd, 2008 RCF Filesystem Changes

 

The new layout

We have moved the /home filesystems for both Merritt and Prairiefire to a single, much much larger fileserver which we believe will be an improvement over our old set up of multiple fileservers (some of which were very old). The major benefits of this change are as follows:

  • Higher reliability overall through Sun's ZFS filesystem and also fewer pieces of hardware (individual servers) to fail.
  • More available space (currently on the order of 31TB after disk redundancy is taken into account) to accommodate future users and special needs. Group quotas are now shared between Prairiefire and Merritt letting us more efficiently use our available free disk space.
  • Easily shared access between your Merritt, Prairiefire, and future RCF system /home directories. For example, you can reference files in /home on Merritt from Prairiefire and visa-versa if you need.
  • Simplified administration. We're not juggling multiple fileservers for different user groups anymore.
  • Note: currently the old Homestead system is not being changed to use the new home fileserver. Homestead will continue to function as it has in the past.

The actual filesystem mounts will look like the following:

/home/<group>/PF/<username>        for home directories on Prairiefire
/home/<group>/MERRITT/<username>   for home directories on Merritt
/home/<group>/SHARED/              ... groups can store shared files here if they wish

 

How this will affect you

While we try to not inconvenience our users, this filesystem change may affect you and some of your programs / scripts. The biggest problem with this change is that any hard references you have to the old layout, such as referencing /home/<group>/<username> in a shell script or program will not work.

We have set the home directories for your login shells to the appropriate location depending on what system you're logged into. For example, if you log into Merritt, your home directory will be /home/<group>/MERRITT/<username>. If you type "cd", or reference ~ or $HOME you will get the expected result. This leads to the following suggestion;

Please use either the tilde (~) or $HOME to reference your home directory in shell scripts / programs that you have. For example, I might use the following method to refer to a program installed in my home directory:

#PBS ...
#PBS ...

cd ~/research/job1
~/bin/my_program job1.input

The reference to 'my_program' above would actually be /home/parkhurst/PF/gattebury/bin/my_program for my user on Prairiefire. Regardless of what we (the system admins at RCF) do to change filesystem mounts and paths in the future, referencing my home directory with ~ (or $HOME) will always work. If you write your scripts and programs in this manner future changes should not affect you.

 

 

If you have any questions or need help modifying your scripts / programs as a result of these changes, please email us at rcf-support@unl.edu and we will make every effort to assist you. Again, we aren't trying to inconvenience our users, but this change may affect those of you who have hard references to your home directory path on Prairiefire or Merritt.

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