Michael Fenn CPSC 620, Fall 09

 Grid computing is the process of allowing loosely-coupled virtual organizations to share resources over a wide area network.  What does this mean? ◦ I’m at Prestigious University ◦ I have some jobs ◦ I want to run them ◦ Well-known State University has idling computers ◦ Grid computing lets me get my jobs there  (Foster, Kesselman and Tuecke, The Anatomy of the Grid: Enabling Scalable Virtual Organzations 2001)

 My usage is bursty ◦ Big paper deadline ◦ End of semester ◦ Etc.  Their usage is bursty  Our bursts don’t coincide  Let’s share  (Armbrust, et al. 2009)

 Many grids, let’s pick one  2 realities ◦ Loosely federated Virtual Organizations (VOs) ◦ Loosely federated sites  2 elements of security ◦ Public Key Infrastructure (PKI) ◦ Web of trust model

 A group of users who share a “common interest” ◦ Definition of “common interest” is flexible  Examples: ◦ High-energy physicists: ATLAS, STAR, CMS, Alice ◦ Bioinformatics: CompBioGrid ◦ Nanotechnology: Nanohub ◦ Just learning: Engagement, OSG-EDU

 Sites are collections of resources  Compute Elements ◦ Globus gatekeeper for authentication ◦ Batch scheduler (PBS, Condor) for getting jobs to compute nodes ◦ Monitoring and accounting to keep the higher-ups happy  Storage Elements ◦ Storage Resource Manager (SRM) for authentication ◦ Big bit bucket for storage ◦ Monitoring and accounting here too

 Public-key infrastructure  Users are affiliated with VOs  VOs issue certificates  Sites trust certificates issued by particular VOs  Confidentiality and Integrity are maintained

 Sites choose which VOs to trust  Resources also have certificates ◦ Users can be confident that the resource is what it claims to be  Sites generally trust the VO that issued their cert ◦ This is not required however!

 3 main types:  VO-User trust ◦ VOs establish criteria for membership  Site-VO trust ◦ Factors in deciding whom to trust  VO requirements  Trust reciprocity  OSG-VO trust ◦ OSG maintains a list of trusted VOs ◦ Trusted VOs have their CA certificates included in the OSG software distribution

 Users have been “accredited” by a VO  If things do go wrong, I have his cert ◦ I know his name ◦ I know who vouched for him  VOs have incentive to maintain well-behaved membership

 OSG runs securely due to: ◦ PKI ◦ Web of trust  Flexible and scalable ◦ I don’t have to make a UNIX user account for everybody  Users are still accountable

 Thank you for listening!