Understanding the Compute Element

Documentation/Release3
UnderstandingComputeElement
Review Passed
by MarcoMambelli
Released
by SuchandraThapa

About this Document

hand This document is for system administrators and users. It provides information about the software installed on a Compute Element and the services provided.

HELP NOTE
Instructions for installing a Compute Element can be found here.

Installation paths

The OSG RPMs install software in filesystem locations following the FHS guidelines. Accordingly most binaries are located in /usr/bin/ or /usr/sbin/ . Unlike with previous OSG Pacman releases, you will not need to source a setup.sh script before working with OSG. The configuration files are all in /etc/ or its subdirectories, with osg-configure and GIP using configuration files in /etc/osg/config.d . Log files are all located in /var/log or its subdirectories. Other OSG output files, such as osg-attributes.conf and other auto-generated files, are located in /var/lib/osg.

Services

The CE services installed by RPMs by default place cron or startup scripts in the appropriate locations (e.g. /etc/init.d) but do not enable or start these services. Admins can enable, start, and stop services using the chkconfig or service commands. E.g. use chkconfig fetch-crl-cron on or service fetch-crl-cron start or service fetch-crl-cron stop to enable, start, and stop the fetch-crl-cron service respectively.

The CE needs to run the globus-gatekeeper, tomcat5 (2), globus-gridftp-server, and the appropriate gratia job manager probe in order to provide the minimal services required of a gatekeeper. In addition, the edg-mkgridmap or the gums-client-cron services will need to be enabled and running depending on whether your resource is using gridmap or gums for authorization. Finally, if your gatekeeper is using any of the RPMs that provides CA certificates and CRLs, the fetch-crl-cron (1) and fetch-crl-boot (1) services should be enabled so that CRLs are up to date.

HELP NOTE
(1) On OSG 3.1.15 and later on EL5 (Centos5 and SL5), fetch-crl3 is installed instead of fetch-crl and the services are called fetch-crl3-cron and fetch-crl3-boot.

HELP NOTE
(2) On EL6 systems tomcat6 is used instead of tomcat5.

The services that are installed on a CE are as follows:

Cron Services

Package Service Notes
  gums-client-cron Created by the gums-client-cron init.d service
gratia-probe-gridftp-transfer gratia-probe-gridftp-transfer.cron Transfers accounting information for gridftp transfers
gratia-probe-pbs-lsf gratia-probe-pbs-lsf.cron Transfers accounting information from PBS or LSF job managers
gratia-probe-condor gratia-probe-condor.cron Transfers accounting information from the condor job manager
gratia-probe-sge gratia-probe-sge.cron Transfers accounting information from the SGE job manager

Init.d Services

Package Service Notes
condor condor  
condor-cron condor-cron  
edg-mkgridmap edg-mkgridmap Generates a gridmap file, only needed if resource is using gridmap files instead of GUMS
osg-info-services osg-info-services Alternative to cemon, not supported currently
globus-gatekeeper globus-gatekeeper Provides the gatekeeper services for jobs
globus-gatekeeper globus-scheduler-event-generator Only needed if the SEG is used (currently only the pbs and sge gatekeeper uses this)
gsi-opensshd gsisshd Provides gsi sshd services
gums-client gums-client-cron Generates the user-vo-map file, and needed if GUMS is being used
tomcat5 tomcat5 (2) Hosts the cemon webapp and needed to report to the BDII
globus-gridftp-server globus-gridftp-server Starts the gsiftp server
fetch-crl fetch-crl-cron (1) Creates a cron job to keep the CRLs up to date
fetch-crl fetch-crl-boot (1) Runs fetch-crl once to update the CRLs, intended to make sure CRLs are up to date when system is starting up

Notes

  1. On OSG 3.1.15 and later on EL5 (Centos5 and SL5), fetch-crl3 is installed instead of fetch-crl and the services are called fetch-crl3-cron and fetch-crl3-boot.
  2. On EL6 systems tomcat6 is used instead of tomcat5.

Inetd Services

Package Service Notes
globus-gridftp-server globus-gridftp-sshftp  

Log file rotation

Log files are now located in /var/log or subdirectories within that directory. Threrefore, you can use the standard logrotate script or it's equivalents to rotate log files, the logrotation configurations for the log files generated by OSG services are located in /etc/logrotate.d. The logrotate configuration files provided handle all of the log files generated by the OSG provided services.


Changing Globus Settings

If you change any settings for GRAM, including

  1. /etc/globus/globus-gram-job-manager.conf,
  2. /etc/globus/globus-condor.conf, or
  3. Contents of the perl jobmanager (which, by the way, will get overwritten on upgrade),
the changes will not take effect until you kill off the old globus-job-manager processes. This is a change from OSG 1.2, as globus-job-manager processes are now persistent.

This can be done with the following command, as root:

[root@ce ~]$ killall globus-job-manager

Comments

Topic revision: r11 - 06 May 2013 - 18:06:15 - MarcoMambelli
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