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: is-datagrid@infn.itwww: marianne.in2p3.fr