Information System User Requirements

Introduction

The following sections present the current status of the existing Information System use cases and the current issues identified for each of them.

Use Cases

Service Discovery

List available grid services: CE, SE, FTS...

Existing implementations

Open issues

• ATLAS feedback (under discussion): Single query to get CE and SE attributes (1) for OSG, ARC and EGI resources. The problem is that nowadays information from all these resources is not available in a uniform way. Information is present in different tools that need to be queried in different ways. Either centralise the information in a unique tool or make sure all available tools can be queried in a uniform way. Possible areas to be investigated:
  • Understand with GOCDB developers the possibility to add more resource information (full (1) list). GOCDB is planning to provide: property bags and multiple endpoints per service.
  • Understand for the extra resource information, how will dynamic information be automatically updated in GOCDB.
  • Investigate "ginfo as a service" as a single point of query to get information from GOCDB and OSG.
• Service discovery via the Information System breaks whenever a resource or a site BDII goes down, while ideally it should not change or disappear even in presence of downtimes.

Software version and platform

Discover what it is the installed software in a subcluster.

Existing implementations

Open issues

None

SE Capacity

Discover dark data, that is data in storage but not in catalog.

Existing implementations

Open issues

• ATLAS feedback: Information about InstalledCapacity vs TotalSize is needed in SRM.
• CMS feedback: CMS cannot use SRM as it is not using space tokens. It needs more fine-grained sizes (per directory).
• The information is often wrong.

CE Status and queues

Ranking CEs for job submission.

Existing implementations

Open issues

• LHCb request: Automatic way to monitor the validity of published information for these attributes and contact sites to fix values if needed. Tracked in IS ticket #3.
• GlueCEStateEstimatedResponseTime is often unreliable or meaningless.

Information System Clients

Existing implementations

Experiment	Description	Involved GLUE 1.3 Attributes	Involved GLUE 2.0 Attributes
ALICE	lcg-infosites	see #8
ATLAS	lcg-info	see #7
CMS	lcg-info, LDAP modules	see #5
LHCb	lcg-info, lcg-infosites, ldapsearch	see #6

Open issues

• All request: improve ginfo to implement the most common queries currently performed by lcg-info, lcg-infosites and ldapsearch.
  • Experiments will provide the list of queries. Tracked in IS ticket #5, #6, #7 and #8.
  • The ginfo development team will provide a plan to update ginfo and provide the requested functionality. Tracked in IS ticket #9.

WLCG Information System Evolution

In June 2015, OSG announced their plans to stop using the BDII to publish their resources (See Slides presented at the WLCG Operations Coordination Meeting in 18th of June). This announcement has triggered the review of the current WLCG Information System and it has been decided to create a task force to evaluate how WLCG is going to cover the existing use cases in the near future. In the following twiki, the TF is described in detail.

WLCG Global Service Registry

The WLCG Global Information Registry was an attempt to bring together information published by different grid infrastructures like EGI and OSG. It shows both information on pledged resources and actual available resources. The WLCG Global Information Registry aims at aiding LHC experiments to configure their own experiment databases for job submissions and storage management.

Meetings

• Information System Meeting with users: Indico Agendas
• Action items: GRIDINFO JIRA tickets

Presentations

• GDB September 2015: WLCG Information System Status
• WLCG Operations Coordination Meeting June 2015: Information System Use Cases
• GDB September 2014: WLCG Information System Status
• White Area Lectures June 2014: The Grid Information System
• CMS Computing Project Office Meeting May 2014: Prototype CMS Information System Based on AGIS (Restricted Access)
• 3rd LHCb Computing Workshop May 2014: BDII Use Cases for LHCb (Restricted Access)
• GDB April 2014: WLCG Information System Status
• GDB December 2013: GSR
• Common Projects Brainstorming November 2013: Information/Configuration Systems
• GDB October 2013: WLCG Information System Status
• GDB March 2013: WLCG Information System Status
• pre-GDB January 2013: Information System and the Experiments
• GDB December 2012: Requirements for GLUE 2.0
• GDB November 2012: WLCG Information System Status and Evolution
• EGI TF September 2012: EMI Registry Pilot Service
• GDB September 2012: Multi-core support in IS
• GDB July 2012: How to identify the best top level BDIIs?
• GDB June 2012: WLCG Information System Status and Evolution
• GDB June 2011: Cached BDII Update and WLCG Information System Use Cases
• GDB May 2011: Update on the WLCG Information System
• GDB January 2011: EMI status and plans and Information System Open Ends
• LCG Management Board December 2010: Short term improvements for the WLCG Information System
• Tier 1 SC Meeting November 2010: Top level BDII proposal
• WLCG Reliability workshop November 2007: BDII story
• GDB March 2007: BDII - The EGEE Information System

Articles

• A Directory Service for Configuring High-Performance Distributed Computations
• Grid Information System Interoperability: The Need For A Common Information Model
• A performance study of monitoring and information services for distributed systems
• Benchmarking Grid Information Systems
• Improving the currency of Information in a large scale grid information system
• Towards a Global Service Registry for the World-Wide LHC Computing Grid

Resources

• Information System Documentation