IBM ServeRAID, User Reference

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Chapter 11. Introduction to the IBM ServeRAID Cluster
Solution
A cluster is a group of independent computer systems that work together as a
single logical system. A client interacts with a cluster as though it is a single server.
In other words, a cluster is a group of computers linked together in such a way that
they share and manage a set of resources that can support a number of users at
the same time.
This high-availability clustering solution is based on a two-server cluster, where both
servers can access the same storage devices, but only one server at a time
controls the storage devices shared by both servers. If one of the two running
servers fails, the remaining server automatically assumes control of the shared
resources managed by the failed server while still controlling its own resources at
the same time. Then, the failed server can be repaired offline without the loss of
time or work efficiency, because the shared data and applications earlier managed
by the failed server are still online to the clients.
When the failed server is operational again, it can be placed back into the cluster;
the resources are reallocated between the two servers and the cluster resumes
normal operation.
A controller is a device that coordinates and controls the operation of one or more
input and output devices, such as workstations, and synchronizes the operation of
such devices with the operation of a system as a whole.
The IBM ServeRAID Cluster Solution, as discussed in this book, uses one of the
following controllers:
v
IBM ServeRAID-4H Ultra160 SCSI controller
v
IBM ServeRAID-4M Ultra160 SCSI controller
v
IBM ServeRAID-4Mx Ultra160 SCSI controller
v
IBM ServeRAID-4L Ultra160 SCSI controller
v IBM ServeRAID-4Lx Ultra160 SCSI controller
The IBM ServeRAID Cluster Solution also uses IBM expansion enclosures, such as
the following:
v IBM Netfinity EXP15 Rack Storage Enclosure
v IBM Netfinity EXP200 Rack Storage Enclosure
v IBM Netfinity EXP300 Rack Storage Enclosure
Note: You can configure only 13 physical drives in an EXP300 enclosure.
You can install the IBM ServeRAID Cluster Solution by using one of the following
software applications:
v Microsoft Cluster Server, which is part of Windows NT Server Enterprise Edition
v Microsoft Cluster Server, which is part of Windows 2000 Advanced Server
Edition.
The following figures show an example of a simple high-availability clustering
solution. The first figure shows a high-level view of a cluster; the second figure
shows a more detailed view of a cluster.
© Copyright IBM Corp. 2002
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