IBM AIX HACMP, Руководство пользователя по оборудованию

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IBM Certification Study Guide AIX HACMP
application on the takeover node when a fallover occurs. For more
information about creating application server resources, see the
HACMP for
AIX, Version 4.3: Installation Guide
, SC23-4278.
2.5.1 Performance Requirements
In order to plan your application’s needs, you must have a thorough
understanding of it. One part of that is to have The Application Planning
Worksheets, found in Appendix A of the
HACMP for AIX Planning Guide ,
SC23-4277, filled out.
Your applications have to be served correctly in an HACMP cluster
environment. Therefore, you need to know not only how they run on a single
uni- or multiprocessor machine, but also which resources are required by
them. How much disk space is required, what is the usual and critical load the
application puts on a server, and how users access the application are some
critical factors that will influence your decisions on how to plan the cluster.
Within an HACMP environment there are always a number of possible states
in which the cluster could be. Under normal conditions, the load is serviced
by a cluster node that was designed for this application’s needs. In case of a
failover, another node has to handle its own work plus the application it is
going to take over from a failing node. You can even plan one cluster node to
be the takeover node for multiple nodes; so, when any one of its primary
nodes fail, it has to take over its application and its load. Therefore, the
performance requirements of any cluster application have to be understood in
order to have the computing power available for mission-critical applications
in all possible cluster states.
2.5.2 Application Startup and Shutdown Routines
Highly available applications do not only have to come up at boot time, or
when someone is starting them up, but also when a critical resource fails and
has to be taken over by another cluster node. In this case, there have to be
robust scripts to both start up and shut down the application on the cluster
nodes. The startup script especially must be able to recover the application
from an abnormal termination, such as a power failure. You should verify that
it runs properly in a uniprocessor environment before including the HACMP
for AIX software.