Detailed Design and Application of Distributed Database Management Systems - High-Performance Web Databases: Design, Development, and Deployment - page 368

for gathering system statistics. Tuning a distributed environment is much
more complex than tuning a centralized system because not only must
monitoring be conducted at each local node, it must also be performed at the
network interface level across the entire distributed environment.
BACKUP, RECOVERY, AND SECURITY PROTECTION
When the distributed DBMS system and the network software encounter
system failure (e.g., hardware or network problems), the prompt restora-
tion to proper functioning is a crucial task to ensure that reliable service is
provided to the users. Providing both physical security and software pro-
tection against unauthorized users are two of the support activities to be
performed by the local and global database administrators. Because secu-
rity is an extensive and complex subject, it is beyond the scope of this
chapter except to say that security requirements must be considered at
every step in the development of a distributed database system.
USER TRAINING AND RESOLVING PROBLEMS
Another important task for the support phase is to provide users with
adequate training on the use of the distributed database system. This task
could also include assigning user account and password numbers and allo-
cating working and permanent storage.
When DBMS vendors put out new versions of their software, it is the
responsibility of the local database administrator to install the new
version. When problems are detected, the support staff must verify and
isolate the problem. The problem should be either fixed or reported to the
appropriate vendors.
SUPPORT REVIEW
The support task is of a continuous nature. Therefore, one or more per-
manent system programmers or engineers should be on duty at all times.
The skills of the support team members and the size of that team will
depend to a large extent on the size and nature of the distributed database
environment and the applications.
CRITICAL SUCCESS FACTORS
The development of a distributed database environment and of distrib-
uted applications are successful only when each phase of the development
is carefully planned and executed. The success of the development of a dis-
tributed environment and distributed applications is difficult to quantify.
Different measures are appropriate for different application areas. Some
commonly perceived measures of success include:
• adequate performance of the overall distributed DBMS applications