Multitasking operating systems, especially real-time operating systems, need to maintain the illusion that all tasks running on top of them are all running at the same time, even though only one or a few tasks really are running at any given moment due to the limitations of the hardware the operating system is running on.
Such multitasking is fairly simple when all tasks are independent from each other.
However, when several tasks try to use the same resource, or when tasks try to share information, it can lead to confusion and inconsistency.
The task of concurrent computing is to solve that problem.
Some solutions involve “locks” similar to the locks used in databases, but they risk causing problems of their own such as deadlock.
Other solutions are Non-blocking algorithms. References • Andrew S.
Tanenbaum, Albert S Woodhull (2006): Operating Systems Design and Implementation, 3rd Edition, Prentice Hall, ISBN 0-131-42938-8 • Silberschatz, Avi; Galvin, Peter; Gagne, Greg (2008).
Operating Systems Concepts, 8th edition.
John Wiley & Sons.
ISBN 0-470-12872-0. Configuration management database 178 Configuration management database A configuration management database (CMDB) is a repository of information related to all the components of an information system.
It contains the details of the configuration items (CI) in the IT infrastructure.
Although repositories similar to CMDBs have been used by IT departments for many years, the term CMDB stems from ITIL.
In the ITIL context, a CMDB represents the authorized configuration of the significant components of the IT environment.
A CMDB helps an organization understand the relationships between these components and track their configuration.
The CMDB is a fundamental component of the ITIL framework’s Configuration Management process.
CMDB implementations often involve federation, the inclusion of data into the CMDB from other sources, such as Asset Management, in such a way that the source of the data retains control of the data.
Federation is usually distinguished from Extract, transform, load (ETL) solutions in which data is copied into the CMDB.
The CMDB records CIs and details about the important attributes and relationships between CIs.
Configuration managers usually describe CIs using three configurable attributes: 1.
Relationship A key success factor in implementing a CMDB is the ability to automatically discover information about the CIs (auto-discovery) and track changes as they happen.
CMDBs contain metadata, and thus the concept overlaps with that of a metadata repository which are both used in running large IT organizations.
Configuration management addresses how the data is to be kept up to date, which has historically been a weakness of metadata repositories. Federated CMDBs Information-technology managers can use a federated CMDB – an enterprise-level CMDB – to accumulate information about configurations, changes and other data from disparate sources. The goal is to enable management data providers to integrate their data into a coherent, seamless CMDB, using an industry-standard interface. The architecture for this standard was proposed in a 2007 white paper, written by representatives from several CMDB vendors: ASG, BMC Software, CA, Fujitsu, HP Software Division, IBM and Microsoft. These members represented the CMDB Federation Workgroup, or CMDBf. In 2009, the Distributed Management Task Force (DMTF) standardized the CMDBf specification to provide a cross-vendor, standardized solution for federating system-management data. References • Office of Government Commerce (OGC), ed.: Service Support.
IT Infrastructure Library (ITIL).
The Stationery Office, Norwich, UK (2000) • OGC, ed.: Introduction to ITIL.
IT Infrastructure Library.
The Stationery Office (2005)      TechWorld.com. “The federated CMDB vision.” (http:/ / features.
Com/ networking/ 3221/ the-federated-cmdb-vision/ ) The Federated CMDB Vision white paper. (http:/ / www.
Org/ CMDB-Federation-white-paper-vision-v1. 0.
Pdf) The Federated CMDB Vision white paper. (http:/ / www.
Org/ CMDB-Federation-white-paper-vision-v1. 0.
Pdf) CMDBf Workgroup (http:/ / www.
Org/ ) Configuration Management Database (CMDB) Federation Specification (http:/ / xml.
Pdf) Configuration management database 179 External links • LiveTime’s Cloud based CMDB (http://www.livetime.com/itil-service-management/service-manager/ configuration-management-cmdb/) • How to build a CMDB (http://www.cmdb.info/p/c_software7.html) with open source software • Get your OpenSource CMDB with iTop. (http://netcmdb.com) iTop is developed by Combodo a French OpenSource Software editor • IBM Tivoli Configuration and Change Management Database IBM CCMDB • HP Universal CMDB (https://h10078.www1.hp.com/cda/hpms/display/main/hpms_content.jsp?zn=bto& cp=1-11-15-25^1059_4000_100__&jumpid=reg_R1002_USEN) • Configuration Management Database (CMDB) Federation Specification (http://xml.coverpages.org/ DMTF-DSP0252-CMDB-Federation.pdf) • CMDBuild – Configuration and Management Database Open Source (http://www.cmdbuild.org) • i-doit Open Source CMDB (http://www.i-doit.org/) • CMDB (http://www.cmdb.org/)
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