Status Report for 06/07/07 to 06/13/07

Issues in using NWS
1. Hostnames
NWS’s memory service, which provides memory service to store NWS sensors’ data, saves data based on NWS sensors’ hostnames. (A hostname is a system name returned by gethostname or ‘hostname -–fqdn’) This can be problem when a master and sensors installed in different clusters and a sensor’s hostname is not a public domain name, i.e., internal hostname. For example, BigRed's hostname is not for publicly accessible from the Internent, rather hostnames are for only internal uses. In this case, NWS’s information extractor, nws_extract , can not show correct data to a user. If the memory service is in the same cluster with sensors, it will be ok but no other sensors outside clusters will be allowed.

2. Manager nodes and computing nodes
NWS’s bandwidth measurement may be incorrect depending on cluster’s topology. For instance, NCSA’s TeraGrid cluster consists of four manager nodes, which have all public hostnames and thus can be accessible from the Internet, and hundreds of computing nodes, whose hostname is not known unless submitting a job. To measure bandwidth before knowing which node will run a job can be difficult. To overcome this possible problem, knowledge on a cluster’s topology or managing policy will be required, if possible, by contacting a help desk.