Il Sistema Operativo OpenVMSCMDA - Centralized Management with Delegated AdministrationDnsManagerListManagerMailboxManagerINSM - Integrated Network Services Manager

CMDA - Centralized Management with Delegated Administration



Centralized Management with Delegated Administration


Often Medium/large organizations composed of several geographically dispersed units, such as CNR, use distributed network services which guarantee maximum flexibility for the single operating units but bear the management and maintenance costs (HW, SW, and human resources) of several servers.

In this context the migration from a distributed to a centralized model would reduce the costs considerably but on the other hand would limit the autonomy of outlying units.

An effective solution may be a hybrid organizational model: partly centralized and partly distributed. The idea is to concentrate the systems management operations in a smaller number of servers (to be evaluated based on an analysis of the network topology, traffic, etc.) keeping the entire distribution of administrative tasks among the organization's operating units by means of delegating by web. We have called this approach Centralized Management With Delegated Administration [1], [2].


Designing systems based on the CMDA model

In order to decide which systems to automate and in what way, we can offer several observations:

  • In general, administrative operations are more frequent than those of system management.
  • Administrative operations require less technical competence than management procedures such as installation, configuration, maintenance and monitoring of systems, requiring highly specialized personnel. For example, assignment of an IP address or the creation of an electronic Mailbox can be easily automated (and can therefore be carried out by non-technical personnel, by means of interaction with web interfaces); however, the configuration of an electronic mail system requires a process of analysis and evaluation of the operating context as well as specialized technical knowledge.
  • Administrative tasks can be distributed between different categories of users with different levels of technical competence. Web interfaces are the tool for distributing administrative tasks and can be "customized" for the various categories of administrators. The authentication mechanisms (user/password or digital certificates) connect the user directly to the type of interface assigned to him.
  • Web interfaces should be simple and intuitive and therefore follow planning criteria according to cognitive models, seeking to limit the number of fields present, of nested windows, etc.;
  • In order to render the system highly flexible, the configuration files of the server include numerous parameters and options, which generally tend to increase or be modified in the new versions. The planning of a web interface for controlling the configuration of a system (for example, Electronic Mail) in its complete generality can lead to an increased complexity of the interfaces produced (aside from the burden of updating them in the case of new versions) and in any case limits the potential of the product. Careful evaluation of the context in which the organization works is necessary in order to decide whether it is appropriate or not to automate technically advanced and rarely used functions.

Based on these considerations the figure below shows the relationships between the frequency of administrative actions and the level of technical skill required. The lower part of the triangle includes very frequent operations requiring a low level of technical knowledge, while toward the apex of the triangle the knowledge level increases and the frequency of the operations decreases.



The mechanism of Delegated Administration, entailing complete distribution of the load between several operators, has proved to be effective for optimizing the use of resources as well as holding down costs.

Based on this model the Integrated Network Services Manager system was designed and developed for integrated management of Electronic Mail, Mailing List, and DNS services [1], [2].



[1] Francesco Gennai, Laura Abba, Marina Buzzi. Exploration of the design of a complex e-mail system. Journal of Computer Resource Management - Computer Measurement Group Inc. Issue: One Hundred, Fall 2000, pp. 14-26 e Conferenze CMG UK 2001, 1-3 Maggio 2001, Edinburgo e CMG Italia 2000, 8-9 Giugno 2000, Milano.

[2]  Francesco Gennai, Marina Buzzi, Laura Abba. Delegated Administration of Network Services. Poster alla Conferenza SANE 2002, 27-31 May, Maastricht (NL).