Topology 'Database'

Many tools (e.g. GridView, reporting tools) need a view of how sites are interconnected. This is multi-dimensional view since each entity (infrastructure provider, VO) can have a different view. Here we collect the information that each has on the topology of the grid.

Topology information sources integration

In this section we elaborate on providing an integration methods for all the sources of Grid topology information.

• List of topology information sources
• Some ideas on topology information integration (proposal 1)

Infrastructure Views

• EGEE - GOCDB
• WLCG - MoU Appendix A - Not in machine accessible form yet.
• OSG

VO Views

ALICE

Alice requires the same services for T0, T1s and T2 sites. It is a QoS matter only. Alice model does not foresee T3 sites. T1 sites are: FZK, CNAF, SARA/NIKHEF, RAL, NDGF.

All sites must provide a VOBOX, so it is easy to have the number of alice sites, as many sites as VOBOXES. Alice has also native Alien sites which are outside of the LCG environment. However these sites must also provide VOBOXES, although they might not be configured as the LCG ones.

The complete list of sites are visible here:

http://pcalimonitor.cern.ch/stats?page=services_status

Here you have the name of the site (Alice name, not GOC DB name) and the name of the VOBOX. The complete set of LCG wites is available in SAM:

https://lcg-sam.cern.ch:8443/sam/sam.py?sensors=VOBOX&regions=CERN&regions=France&regions=GermanySwitzerland&regions=Italy&regions=CentralEurope&regions=NorthernEurope&regions=SouthEasternEurope&regions=SouthWesternEurope&regions=Russia&regions=AsiaPacific&regions=USCMS&regions=USATLAS&vo=alice&order=RegionName&funct=ShowSensorTests

ATLAS

• http://atlas.web.cern.ch/Atlas/GROUPS/DATABASE/project/ddm/releases/TiersOfATLASCache.py

CMS

• https://twiki.cern.ch/twiki/bin/view/CMS/SiteDB
• https://vocms08.cern.ch/sitedb/sitelist/

LHCb

The T2-T1 mapping is handled via a LHCb specific Configuration Service. In order to retrieve these information Roberto has written a script that queries the CS and returns a dictionary T2:T1. Everyone can call it through the simple command:

/afs/cern.ch/user/s/santinel/public/development/T1mapping.sh

The DIRAC services all run on the central WMS instances. These are volhcb01/02 and lxgate03 (as also available from the page https://twiki.cern.ch/twiki/bin/view/LCG/ListOfLhcbDedicatedServices describing all LHCb dedicated service at CERN).

At the T1 there are further agents (transfer agents, failover mechanism, messagging and logging service) running on the VO-BOXes.

As far as concerns the LCG services at T1 the sites should provide SRM, FTS and LFC read-only mirrors. Each T1 signed a MoU guaranteeing some availability. Pledged resources are available https://twiki.cern.ch/twiki/bin/view/LCG/LhcbPlans

-- JamesCasey - 18 Jul 2007