Where Not to Run
By templedf on Jun 26, 2008
Reuti just reminded me of a nice application of one of the new features we added in Grid Engine 6.1. Before 6.1, resource requests were limited to simple boolean AND and OR expressions. For example, when submitting a job, a user might request "-l a=sol-x\*|sol-amd64 -l mem_free=4G -l exclusive=TRUE", meaning that the job must run on a Solaris i386 or AMD64 machine, and the machine must have at least 4GB of memory free, and the job wants exclusive access to the host. (AND is represented by multiple -l switches.) There was no way, however, to request, for example, Solaris on anything but x86.
Enter 6.1. With 6.1 we introduced full boolean expressions for resource requests. A user can now make requests like, "-l a =sol-\*&!sol-sparc\*". (The job must run on Solaris, but not on SPARC or SPARC64.) Even better, you make create complex boolean statements, like "-l (sol-\*&!\*-x86)|(lx2-\*&!(\*-x86|\*-ia64))". (The job must run on either Solaris on anything but x86 or Linux on anything except x64 or Itanium.)
Now, to the title problem. In the email that prompted this post, Reuti responded to a question about how to submit a job to any host, except for one. With 6.1, the answer is simple. Grid Engine has a built-in complex called hostname, or h for short. Using the new boolean expressions, it's very simple to request "-l h=!badhostname", which allows the job to run on any machine except the one named badhostname.