After completing this lesson, you should be able to do the following:
Describe the factors that affect planned and unplanned downtime
Describe the basic components of Oracle Data Guard
Explain the differences between physical and logical standby databases
Explain the benefits of creating a Data Guard environment
Explain the use of Data Guard in high-availability architectures
For small, medium, and large businesses, it is critical to provide high availability of data for both
customers and employees. The objective behind disaster recovery and business continuance plans is
accessibility to data anywhere and at any time. Meeting these objectives is all but impossible with a
single data center. The single data center is a single point of failure if a catastrophic event occurs. The
business comes to a standstill until the data center is rebuilt and the applications and data are restored....
Frequently, the only protection for a URL is that links to that page are not presented to unauthorized
users. However, a motivated, skilled, or just plain lucky attacker may be able to find and access these
pages, invoke functions, and view data. Security by obscurity is not sufficient to protect sensitive
functions and data in an application. Access control checks must be performed before a request to a
sensitive function is granted, which ensures that the user is authorized to access that function....
Immune-Mediated Injury The recovery of marrow function in some patients prepared for bone marrow transplantation with antilymphocyte globulin (ALG) first suggested that aplastic anemia might be immune-mediated. Consistent with this hypothesis was the frequent failure of simple bone marrow transplantation from a syngeneic twin, without conditioning cytotoxic chemotherapy, which also argued both against simple stem cell absence as the cause and for the presence of a host factor producing marrow failure.
Laboratory data support an important role for the immune system in aplastic anemia.
We describe the use of XML tokenisation, tagging and mark-up tools to prepare a corpus for parsing. Our techniques are generally applicable but here we focus on parsing Medline abstracts with the ANLT wide-coverage grammar. Hand-crafted grammars inevitably lack coverage but many coverage failures are due to inadequacies of their lexicons. We describe a method of gaining a degree of robustness by interfacing POS tag information with the existing lexicon.
This handbook is intended to help engineers in industry
with the operation and maintenance of machinery. It
gives the information that these engineers need in a
form that is instantly accessible and easy to read.
The manufacturers of machinery provide guidance on
the operation, lubrication and maintenance required for
their particular machines.
The microcontroller is an exciting new device in the field of electronics
control. It is a complete computer control system on a single chip.
microcontrollers include EPROM program memory, user RAM for storing
program data, timer circuits, an instruction set, special function registers,
power on reset, interrupts, low power consumption and a security bit for
software protection. Some microcontrollers like the 16F818/9 devices include
on board A to D converters.
Structural Testing is used to verify the static strength, or fatigue strength of a component by applying measured loads to the test item. Testing can be done to failure, to contractual requirements or to validate finite element model predictions. DTB has successfully completed thousands of structural tests on items ranging in size and complexity from simple coupons to entire aircraft.
Fatigue Testing is carried out with the objective of determining the relationship between the stress range and the number of times it can be applied before causing failure....
This manual explains why Windows slows down and what you can do to prevent this from happening too quickly. We will explain how to store your data to reduce disk fragmentation, how you should properly remove programs to avoid registry junk, which system maintenance tools you should use to maintain a top notch performance, how to protect your system from malware attacks, and how to physically clean your machine to avoid hardware damage and failure.
The term “ smart grid” defi nes a self - healing network equipped with dynamic optimization
techniques that use real - time measurements to minimize network losses, maintain
voltage levels, increase reliability, and improve asset management. The operational data
collected by the smart grid and its sub - systems will allow system operators to rapidly
identify the best strategy to secure against attacks, vulnerability, and so on, caused by
Coverage: In WSN, each sensor node is given a glimpse of the environment. This follows
are limited in range and accuracy (Figure 1), it can only include a limited physical area of
environment. Therefore, coverage is also an important design parameter in WSNs.
Each node receives a local view of its environment, limited by the scope and accuracy of it. the
coverage of a large area composed by the union of a number of smaller insurance.
Connectivity: Most of the high density of WSNs sensor, thus preventing the isolation of the nodes.
Whether a terrorist attack, fibre cut, security breach, natural disaster or traffic overload, today's networks must be designed to withstand adverse conditions and provide continuous service. This comprehensive, leading-edge book reveals the techniques and strategies to help you keep enterprise data and voice networks in service under critical circumstances. You learn numerous ways to minimize single points of failure through redundancy and backups, and discover how to select the right networking technologies to improve survivability and performance....
Finally, the requirements that a fund has to fulfill in order to be included in the SIF's listing
of SRI funds are not stringent. For example, a fund could be on the list just by having a formal
policy of excluding companies with interests in the tobacco business. If the constraints that SRI
(as defined in our data set) imposes on fund managers are minor, the performance of SRI mutual
funds should not be expected to be lower than that of conventional funds. It is important to
highlight that the estimated performance differences between SRI and conventional funds
Policy-relevant background – This is an
estimate based on air pollution models of the
natural background ozone concentrations that
would exist without sources of air pollution
from human activity, and therefore cannot be
affected by emissions control efforts (Fiore
Our memory access mechanism provides hardware sup-
port for unprivileged malicious software by allowing ac-
cess to privileged memory regions. Malicious software
triggers the attack by forcing a sequence of bytes on the
data bus to enable the memory access circuits. This se-
quence can be arbitrarily long to avoid false positives
and the particular sequence must be agreed upon be-
One of the major responsibilities of a database administrator (DBA) is to ensure that the database is available for use. The DBA can take precautions to minimize failure of the system.
In spite of the precautions, it is naive to think that failures will never occur. The DBA must make the database operational as quickly as possible in case of a failure and minimize the loss of data.
To protect the data from the various types of failures that can occur, the DBA must back up the database regularly. Without a current backup, it is impossible for the DBA to...
Given the range of content available to internet users at effectively zero cost
compared with those available to purchase through established social networks, a
rational, economic decision would be primarily to use the internet to obtain
counterfeit digital goods. However, our data shows this is not the case, suggesting that
purely economic approaches to the purchase of counterfeit goods have limited value
in explaining consumption patterns. Further, accessing illegal content via the internet
offers an element of anonymity to users.
All these changes have a huge impact on the way the database
query optimizer works. Having user-defined functions deep in-
side the query plans makes cost estimation problematic. Having
real data with high skew has always been problematic, but in this
new world the relational operators are just the outer loop of a non-
procedural program that should be executed with the least cost
and in parallel.
Cost-based static-plan optimizers continue...
Extent of knowledge sharing: Related to the above problem is the question of how much knowledge is available
to the system during its query optimization process. In particular, the ﬁrst step in choosing a query evaluation strategy
is likely to be identifying which nodes have materialized views that can speed query processing. A simple technique
would be to use a centralized catalog of all available views and their locations, analogous to the central directory used
by Napster. Yet this model introduces a single point of failure and a potential scalability bottleneck.