What is the SRB
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The Storage Resource Broker (SRB) is a Data Grid Management System (DGMS) or simply a logical distributed file system based on a client-server architecture which presents the user with a single global logical namespace or file hierarchy.
The SRB DGMS has features to support collaborative management of distributed data including: controlled sharing, publication, replication, transfer, attribute based organization, data discovery, and preservation of distributed data. The SRB has become a default DGMS for collaborative data management in multiple academic data centers around the world including: US, UK, Taiwan, Australia, Japan, and more countries. It is estimated that SRB brokers more than 1.5 Petabytes of data worldwide.
In the above example, a screen shot is provided of a Windows browser that can be used to access a SRB shared collection. The left-hand side shows not only the file hierarchy, but also the metadata and permissions that are set for each directory. The right-hand side shows the files present within the "files-1" sub-directory. Note that even though the files are distributed across multiple storage systems (shown under "Resource"), the logical collection has assembled a view on the files into a single logical sub-directory.
The SRB manages the name spaces used to identify files, storage resources, users, metadata, and access controls independently of the physical storage systems. Thus the logical name used to identify a file does not change as the file is moved to other storage systems. The access controls on the file do not change as the file is moved, and the metadata associated with the file remain attached to the file or directory. In the above example, two metadata items are linked to the directory "SRB_Tutorial". The date of the tutorial and the instructor are listed along with the sub-directories.
The SRB DGMS is a middleware in the sense that it is built on top of standard file systems (Unix, Windows, Linux, Mac OS X), commercial archives (HPSS, UniTree), academic archives (NCAR MSS, Castor, Dcache, Atlas), relational databases (Oracle, DB2, Sybase, Informix, Postgresql, mySQL) and special storage devices such as object ring buffers. Data stored into any of these systems can be organized into a logical collection. The SRB has callable library functions that can be utilized by higher level software. However, it is more complete than many middleware software systems as it implements a comprehensive distributed data management environment, including end-user client applications such as load libraries (Windows, Perl, Python), browsers (web, Windows), digital libraries (DSpace, Fedora, OAI-PMH), workflows (WSDL, Kepler actors, Matrix), and Unix style shell commands.