ATLAS Grid Requirements A First Draft Rich Baker Brookhaven National Laboratory

What Will the Grid do for ATLAS? Manage Data Manage Resources –CPU- Storage –Network- Other? Manage Security/Authentication Track Resource Utilization Control Task Execution

Manage Data Abstraction of Data from Physical Storage Global Name Space for Named Data Objects –i.e. /gds/atlas/myusername/myanalysis/myntuple –User and Group Level Access Control Allow Various Levels of User Control –Move, Copy, Replicate commands –“Smart” Features Should be Responsibility of Task Manager Perhaps

Manage Data (2) Replica Management –Most Data Will Be Read Only After Creation –Some Data Will Require Active Management –Replica Manager Should Understand Difference “Virtual Data” Not a Primary Concern (?) Compatible with Multiple File Systems, Databases, Storage Managers, … Local Control & Fault Tolerance

Manage Resources Keep Track of All Available Computing Resources Local Registration - Global Discovery Fault Tolerant Dynamic

Manage Security & Authentication User Credentials Created at Logon Allow Task Execution and Resource Use Across Administrative Domains Compatible with Various Local Security Implementations Must Scale Reasonably –Can We Manage Millions of User Accounts? –Will All Sites Allow “Generic” Users? A Thorny Issue!

Track Resource Utilization User & Group Accounting Sufficient to Serve as Input to Resource Allocation Algorithms Absolutely Essential if Resources are to be Shared “Fairly”

Control Task Execution Automagic? Perhaps Eventually Initial Focus –Allow Submission, Monitoring & Control –Fault Tolerance - Retry Options –Allow Specification of Input/Output Options –Output Collection / Merging

Commentary Requirements Will Evolve Good General Concept of What is Needed Specifics Needed, but Difficult to Define Without Experience Important to Start Using Grid Services in “Production” Environments ASAP To Be Continued…