The Information System (Information Index (II))

The information system within the LCG grid framework provides information about grid resources and their status. The implementation is provided by the Globus Monitoring and Discovery Service (MDS) which uses OpenLDAP and implements the GLUE (Grid Laboratory for a Uniform Environment) Schema. More specifically, local Grid Resource Information Servers (GRISes) monitor the state of CE's and SE's at the site. On top of this layer is the BDII (Berkley Database Information Index) which queries the local GRISes for information and caches it. Users and other grid-services (e.g. resource brokers) can interrogate the BDII's for information about available resources.

As an aside, in the original Globus implementation, GRISes would publish their information in a site Grid Information Index Server (GIIS). The replacement of the GIISes with BDII was due to the GIIS system not being overly scalable in addition to (often) containing incorrect information.