NQS - An Overview

The Network Queueing System ( NQS ) batch system has been installed on LNF UNIX Environment and is used for batch job submission. A NQS job is a series of UNIX commands combined in a Shell script. NQS works by using the job queues and the NQS on LNF UNIX Cluster distinguishes beetwen two types of queue:

Batch queue

Batch queues are defined on each system in NQS domain. Each queue has different resources limits, in particular the CPU time.

Pipe queue

Pipe queues are a mechanism to distribute jobs and balance the workload evenly over the destination servers. Users submit to the pipe queue, and the load balancing software in NQS finds an empty server in which has to run the job. If all servers are full, then the job is put on wait state. If more than one job are on wait state, than the next job to be started is determined by an intelligent script which is aware of the current state of running and queued jobs. The following subsection describes the batch environment in more detail.