Specifications

Chapter 3. UPS configurations for cluster 27
Chapter 3. UPS configurations for cluster
There are two different ways to use UPS units:
• Single power line: one UPS for both servers, controllers, and enclosures. This
will be used in small cluster configurations or with a large UPS (Symmetra).
• Double power line: two UPS units, one UPS for each server, controller and
enclosures are connected to both UPS units. This will be used in large data
centers with two independent power lines.
In a complete solution, this would be combined with UPS software that utilizes the
cluster API. Since such software does not exist at present, another solution is
required. A simple command file UPS.CMD is sufficient, but works only for
two-node clusters.
We recommend that the operating system of the cluster is installed in the English
language. We developed the command file, UPS.CMD, with the English version
of Microsoft Windows NT 4.0 Enterprise Edition. The messages may be different
if any other language than English is installed. The command file depends on the
exact spelling of English messages. For use with other languages, UPS.CMD has
to be adapted.
Every time the command file UPS.CMD is used, it makes an output redirection
into a log file LOG.TXT. This log file contains events related to the UPS.
As a test we used an MSCS solution with two IBM Netfinity 8500Rs (8681), an
IBM Netfinity Fibre Channel RAID Controller Unit (3526) with six IBM Netfinity
EXP15 (3520) storage expansion enclosures, and two IBM Netfinity Fibre
Channel hubs (3523). We implemented this cluster with two redundant Fibre
Channel loops. The computer name for the first Netfinity was NF8500L (Netfinity
8500 left), for the second Netfinity NF8500R (Netfinity 8500 right). On both
nodes, Microsoft Windows NT 4.0 Enterprise Edition with Service Pack 5 was
installed. The language of the operating system was English. Two virtual file
servers (VFS) were defined as cluster resources. Each virtual file server had its
own group with the names VFS_A and VFS_B. In each group we defined an IP
address, a network name, a shared disk resource, and a file share.
3.1 General UPS configuration rules
Note: Our solution is based on the command file UPS.CMD. It is mandatory that
the administrator adapt this file according to the cluster configuration. For details,
see Chapter 4, “The command file UPS.CMD” on page 67.
It is important to understand which actions the UPS performs when a power
loss is detected. These issues are discussed in 3.1.1, “Timing of UPS actions”
on page 28. Then we consider UPS capacity planning in 3.1.2, “UPS capacity
planning” on page 29 and recovery in 3.1.3, “Recovery” on page 30.
Important