INFN experience with Globus GIS A. Cavalli - F. Semeria INFN Grid Information Services workshop CERN, March 2001

Introduction › In a distributed environment like a Grid, one of the primary needs is to collect and retrieve resource information. › Whithin the Globus model the Grid Information Service (GIS) is the way of making information available to Grid application.

GIS=GRIS+GIIS › Globus implements the GIS by using two kinds of LDAP servers:  GRIS (Grid Resource Information Service) runs on each resource (machine). It uses an LDAP shell backend to gather the resource configuration and status. It registers itself to a GIIS providing info about itself.  GIIS (Grid Index Information Service): LDAP server that runs on an organizational server that collects and caches information provided by GRIS’s registered under it

INFN implementation › INFN implemented a hierarchical structure of GIIS based on INFN departments (about 25) › Each GRIS registers itself to the site GIIS which in turn registers itself to the top level INFN GIIS

Top level GIIS dc=infn,dc=it,o=grid GIIS Milano GRIS dc=mi,dc=infn,dc=it,o=grid GIIS Bologna GRIS dc=bo,dc=infn,dc=it,o=grid

Information flow › Information is not pushed periodically from a GRIS to a GIIS, but is the GIIS that queries the GRISes when an application needs information › Information is stored in cache for a period of time (TTL=Time To Live) › The higher the level of GIIS, the higher the TTL, the lower the level of detail

INFN GIS implementation › 11 GIIS’s registered › More than 40 GRIS’s › Its content is browsable via the URL bin/mdsbrowse1.pl

GIS for DataGrid testbed › The proposed implementation for the DataGrid testbed is to have a hierarchical structure of GIIS having a root server at CERN. › Each organization has its top level GIIS registered on the root server, but can choose its own low level topology.

CERN ROOT GIIS “O=Grid” INFN GIIS “dc=infn, dc=it, o=Grid” IN2P3 GIIS “dc=in2p3. dc=fr, o=Grid” LIP GIIS “dc=lip, dc=pt, o=Grid” … DEP. / LAB. GIIS “dc=xx, dc=infn…” DEP. / LAB. GIIS “dc=yy, dc=infn…” DEP. / LAB. GIIS “dc=zz, dc=infn…” GRISes … FRENCH GIIS “dc=fr, o=Grid” … DEP. / LAB. GIIS “ou=xy, dc=in2p3…”

INFN GIIS “dc=infn, dc=it, o=Grid” MILANO GIIS “dc=xx, dc=infn…” BOLOGNA GIIS “dc=yy, dc=infn…” INFN CMS EXPERIMENT GIIS “dc=infn, dc=it, ou=cms, o=Grid” GRISes … CERN CMS EXPERIMENT GIIS “ou=cms, o=Grid” Experiments’ resources: topology

{deploy}/etc/grid-info-site.conf (…) # this entry is for access-control only. # it uses all the global configuration data set above. dn: service=MDS Resource, hn=*, service=MDS Registration, dc=*, dc=infn, dc=it, o=Grid Experiments’ resources: “howto”

Some tests › We have tested the performance dependency from caching and cpu load. › Tests have been made on WAN. › The same queries on a GIIS take 10 sec. when off

Some tests (cont.) › When a GRIS has a loaded CPU the response time from its own GIIS is much longer when the cache is expired (> 1 min. vs 1 sec.) › Also when a GIIS has a loaded CPU and the cache is not expired the response time is longer (6-7 sec.): it happens with GIIS also used for computation…

Performance › In the worst case the whole set of machines must be queried. › Some indexing techniques should be used to implement search space pruning (currently the GIIS backend always fetches data for every registered host). › Also a periodic information update mechanism can be investigated.

Security and access policies › In the current implementation any machine can register itself to a GIIS › No access control when searching the GIIS. From any ldap client I can: ldapsearch –p 389 –h mds.infn.it –b “o=grid” –s sub “*=*” and get all the information from the GIIS

Conclusions › The Globus Information Service is based on a standard protocol (LDAP). › It provides flexibility and a potentially good distributed data model. › But...

Conclusions (cont.) › A good topology for the HEP experiments must be still implemented › The GRIS must be extended with new information providers › Lack of server redundancy/replication › Performance & security must be improved › Superior knowledge: referral to upper GIIS not implemented › all the information is represented in text format -> no numerical comparison allowed

› Generalizing GIS documentation for DataGrid (see also: INFN kit 1.3). › Preparing to test the alpha release of the new MDS infrastructure:  OpenLDAP 2.0  GSI authentication  Improved backend performance › Investigating on LDAP: aliases, referrals, LDBM… › Data replication (with Netscape?) Work in progress & todo

Documentation › The documentation is currently on: where pointers can be found for:  INFN Globus documentation (  INFN Globus toolkits distribution (  INFN testbed ( › For testbed Information Service support: mailing www:marianne.in2p3.fr