Last modified: Fri May 30 14:16:03 BST 2008
Nick West
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Grid: The GLUE Schema

The data published in the Information Service conforms to the GLUE (Grid Laboratory for a Uniform Environment) Schema, which defines a common data model to be used for resources monitoring and discovery.

This page gives information about the Monitoring and Discovery Service (MDS), namely the Lightweight Directory Access Protocol) (LDAP) implementation of the GLUE Schema. It has been extracted from @ LCG-2 User Guide: Appendix The GLUE Schema

Information is organised into objectclasses, each of which contains zero or more attributes. Having found an attribute you want to examine you can use the ldapsearch command to obtain it, for example:- 

  ldapsearch -x  -h lcg-bdii.cern.ch -p 2170  -b "mds-vo-name=local, o=grid" \
     'objectclass=GlueCEState' GlueCEStateStatus

Information is organised into the following:-

General Attributes

This group includes some base (top) object classes, which have no attributes, and, thus, no actual resource data, and some other that include general attributes that are defined in entries of both CEs and SEs. These are the version of the schema that is used, the URL of the IS server and finally the GlueKey, which is used to relate different entries of the tree and in this way overcome OpenLDAP limitations in query flexibility.

ObjectclassAttributes
GlueTop None
GlueGeneralTop None
GlueSchemaVersion Schema version
GlueKey
GlueInformationService The Information Service URL
GlueService Service detals, including type, status, owner etc.

Attributes for the Computing Element

These are attributes that give information about a CE and its composing WNs. In the GLUE Schema, they are defined in the UML diagram for the Computing Element.

ObjectclassAttributes
GlueCETop None
GlueClusterTop None
GlueCE Service ID and name
GlueCEInfo Batch name + version, gatekeeper host + manager, number of CPUs,
Application and data directories, default SE etc.
GlueCEState Queue and jobs statistics, response times etc.
GlueCEPolicy Limits on time and number of jobs
GlueCEAccessControlBase Vo restrictions
GlueCEJob Individual job info (currently not filled?)
GlueCluster Cluster ID and name.
GlueSubCluster Sub-cluster ID and name, temporary directories and CPU counts.
GlueHost Host ID and name.
GlueHostArchitecture Platform description, CPUs in a SMP node
GlueHostProcessor CPU information: name, version, speed, l1 and L2 cache sizes.
GlueHostApplicationSoftware List of installed software.
GlueHostMainMemory RAM and virtual memory size
GlueHostBenchmark SpecInt2000 and SpecFloat2000 benchmarks.
GlueHostNetworkAdapter Card name and IP, in and out permissin connectivity
GlueHostProcessorLoad Load statistics
GlueHostSMPLoad SMP load statistics
GlueHostOperatingSystem OS name, version and kernel.
GlueHostLocalFileSystem Local file system name, type, size etc.
GlueHostRemoteFileSystem Remote file system name, type, size etc.
GlueHostStorageDevice Host storage system name, type, transfer rate.
GlueHostFile File name, size, dates, latency, lifetime, owner.
GlueLocation Location ID, name, path, versin
GlueVOView Local ID for this VO view

Attributes for the Storage Element

These are attributes that give information about a SE and the corresponding storage space. In the GLUE Schema, they are defined in the UML diagram for the Storage Element.

It is worth noting that the GlueSE object class, which maps to the StorageService element in the GLUE Schema, publishes information of the manager service of a SE; the GlueSL object class, which maps to the StorageLibrary element, publishes information related to the access node for the SE; and the GlueSA object class, which maps to the StorageSpace element, gives information about the available space in the SE.

ObjectclassAttributes
GlueSETop None
GlueSLTop None
GlueSATop None
GlueSE Storage service ID and name, number of ports, capacity, architecture.
GlueSEState System load
GlueSEAccessProtocol Access protocol type, port, version. Security, access time, network endpoint etc.
GlueSEControlProtocol Control protocol type, version. Network endpoint etc.
GlueSL Storage library name, host ID, service ID.
GlueSLLocalFileSystem Local file system name, type, read-only type, capacity.
GlueSLRemoteFileSystem Remote file system name, type, read-only type, capacity.
GlueSLFile File name, size, dates, latency, lifetime.
GlueSLDirectory Directory name, size, dates, latency, lifetime.
GlueSLArchitecture Type of storage hardware
GlueSLPerformance Bandwidth
GlueSA Storage space path, ID, lifetime etc.
GlueSAPolicy File size and lifetime limits. Job file limits.
GlueSAState Used and available space.
GlueSAAccessControlBase Access control rules

Attributes for the CE-SE Binding

The CE-SE binding schema represents a mean for advertising relationships between a CE and a SE (or several SEs). This is defined by site administrators and is used when scheduling jobs that must access input files or create output files from or to SEs. In the GLUE Schema, they are defined in the UML diagram for the Computing Element - Storage Service - Bind.

ObjectclassAttributes
GlueCESEBindGroup Associations between an CE and one or more SEs
GlueCESEBind Associations between an SE and a CE

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