Abstract: Recently, grid computing has been widely focused on
the science, industry, and business fields, which are required a vast
amount of computing. Grid computing is to provide the environment
that many nodes (i.e., many computers) are connected with each
other through a local/global network and it is available for many
users. In the environment, to achieve data processing among nodes
for any applications, each node executes mutual authentication by
using certificates which published from the Certificate Authority
(for short, CA). However, if a failure or fault has occurred in the
CA, any new certificates cannot be published from the CA. As
a result, a new node cannot participate in the gird environment.
In this paper, an off-the-shelf scheme for dependable grid systems
using virtualization techniques is proposed and its implementation is
verified. The proposed approach using the virtualization techniques
is to restart an application, e.g., the CA, if it has failed. The system
can tolerate a failure or fault if it has occurred in the CA. Since
the proposed scheme is implemented at the application level easily,
the cost of its implementation by the system builder hardly takes
compared it with other methods. Simulation results show that the
CA in the system can recover from its failure or fault.
Abstract: Recently, the improvements in processing performance
of a computer and in high speed communication of an optical fiber
have been achieved, so that the amount of data which are processed
by a computer and flowed on a network has been increasing greatly.
However, in a client-server system, since the server receives and
processes the amount of data from the clients through the network, a
load on the server is increasing. Thus, there are needed to introduce
a server with high processing ability and to have a line with high
bandwidth. In this paper, concerning to P2P networks to resolve the
load on a specific server, a criterion called an Indexed-Priority Metric
is proposed and its performance is evaluated. The proposed metric is
to allocate some files to each node. As a result, the load on a specific
server can distribute them to each node equally well. A P2P file
sharing system using the proposed metric is implemented. Simulation
results show that the proposed metric can make it distribute files on
the specific server.