- Doc Structure
- A Globus Primer
- Globus Is Modular!
- Installing GT
- Platform Notes
- Migrating from GT2
- Migrating from GT3
- PDF version
- Best Practices
- Coding Guidelines
- API docs
- Public Interfaces
- Resource Properties
- Performance Studies
Table of Contents
This section is a loose collection of frequently asked questions about the MDS4. It includes mostly information about what the MDS4 is and what Information Services are included in the Globus Toolkit 4+. The goal is to have it grow over time with common user questions and for this to become a frequently used resource.
Q: What's the difference between Pre-WS MDS, MDS2, WS-MDS, and MDS4?
A: MDS2 (also known as Pre-WS MDS) was the LDAP based monitoring/discovery/information publishing system implementation distributed with various Globus Toolkit versions starting with GT2. GT4 also includes a deprecated release of MDS2, but its use is generally discouraged due to operational and scalability limitations as well as security issues. WS-MDS (also know as MDS4) is the more recent WebService based Monitoring and Discovery Service that is fully integrated with the rest of GT4. You can view more information about MDS2 and MDS4 (respectively) here: http://www.globus.org/toolkit/docs/4.0/info/prewsmds/PreWSMDSFacts.html and http://www.globus.org/toolkit/docs/4.0/info/
Q: What is the MDS4 Index Service?
A: The Index Service collects monitoring and discovery information from Grid resources, and publishes it in a single location; generally, it is expected that a virtual organization will deploy one or more index services which will collect data on all of the Grid resources available within that virtual organization. Read more information about it here: http://www.globus.org/toolkit/docs/4.0/info/index/
Q: What is the MDS4 Trigger Service?
A: The Trigger Service collects data from resources on the grid and, if administrator defined rules match, can perform various actions. An example use is to send email when queue length on a compute resource goes over a threshold value. Read more information about it here: http://www.globus.org/toolkit/docs/4.0/info/trigger/
Q: How do I query the MDS4 Index?
A: There are a number of ways to access the information in the Index Service. The most common is using the command line tools described here: http://www.globus.org/toolkit/docs/4.0/info/index/user-index.html Some common queries are also described here: http://www-unix.mcs.anl.gov/~robertm/xpath-queries.html You can also access the information programmatically using the Java based API See http://www.globus.org/api/javadoc-4.0/globus_java_ws_core/org/globus/wsrf/query/package-tree.html for some more detail.
Q: I've already installed Ganglia/Hawkeye, but it isn't showing up in the MDS4 Index when I start it. How do I configure the Index so that the Ganglia or Hawkeye data is in it?
A: Read how to configure either of these here: http://globus.org/toolkit/docs/4.0/info/key/gluerp.html
Q: NEXT QUESTION?
A: ANSWER ME!