Linux cluster

• The department is a major sponsor of the school's high-performance Linux computing cluster, which contains more than 100 nodes (390 CPUs) as of July 2009. This resource is the major research computing capability available to the department, and is the appropriate tool for heavy-duty research computing. Department members can request an account by contacting Oliver Hofmann.

Unix

• Availability
  The School (HSPH) runs a Sun server known as hsph. hsph can be accessed through all PC's in the department via an X-Window emulation software (Xmanager). All major mathematical and statistical software needed in the coursework is installed on hsph. In the past, hsph has acted as the mail server for the School, which has limited its usefulness for research on it. As of fall 2006, this is ending, and the server may be useful for research.
• Security
  Unix password is at the same time your e-mail password. The same rules apply to choosing a good password as in the PC section of this document. The "passwd" command is used to change your password.
• Disk space
  Each student in biostatistics is assigned 100MB of disk space on hsph, while postdocs are assigned 300Mb. Faculty members should discuss their needs with Bill Mahoney in the IT department. The "quota -v" command will give you the current usage of the disk space. The "du" program will also show you the disk space utilization of the current directory and its subdirectories. In order to make the most use of the disk space ``gzip'' is the recommended tool to compress the files. gzip file will create a compressed file file.gz In order to recover the original file, use the command gunzip file.gz
  
  Research students (3^rd year and above), with the permission of their advisor, can obtain additional disk space through Bill Mahoney in IT (bill@hsph).
• File permissions
  By default, files that you create on hsph are readable only by you. You can use the "umask" command in your .cshrc file to change the default creation mask for new files and directories, and the "chmod" command to modify the protections on particular files or directories. A "umask 22" in your .cshrc file will allow the access to your newly created files and directories for everybody. "chmod 700 directoryname" will turn off all access bits for an existing directory. "chmod 755 directoryname" will enable access for a directory, and "chmod 644 filename" will allow access for a particular file. See "man chmod" for details.
• Online documentation
  The "man" command is the main source of online documentation. Running the command "man date" will provide information on the "date" command, and "man -k date" will lookup any references to commands which include the string "date" in their terse description.