INFN experience with Globus GIS A. Cavalli - F. Semeria INFN Grid Information Services workshop...
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Transcript of INFN experience with Globus GIS A. Cavalli - F. Semeria INFN Grid Information Services workshop...
INFN experience with Globus GIS
A. Cavalli - F. SemeriaINFN
Grid Information Services workshop CERN, 28-29 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 1.1.3 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 GIISdc=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
http://bond.cnaf.infn.it/cgi-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”
MILANOGIIS
“dc=xx, dc=infn…”
BOLOGNAGIIS
“dc=yy, dc=infn…”
INFN CMS EXPERIMENTGIIS
“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 < 1 sec. when cache is on and > 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: www.infn.it/grid where pointers can be found for:
INFN Globus documentation (www.infn.it/globus)
INFN Globus toolkits distribution (www.pi.infn.it/grid/dist)
INFN testbed (www.infn.it/testbed-grid)
› For testbed Information Service support:mailing list: [email protected]: marianne.in2p3.fr