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An Introduction to UPS for Power Systems

Uninterruptible power supplies (UPSs) provide immediate battery backup capability during a utility outage or service disruption. Since most servers don’t include internal batteries capable of supporting the entire load, a loss of power or an electrical fluctuation beyond the server’s power supply specification will result in a crash. A crash means system downtime and possibly corrupted data. The UPS internal batteries, surge suppression and line filters protect against nine of the most common power problems: power failure, power sag, power surge, undervoltage, overvoltage, line noise, frequency variation, switching transients and harmonic distortion. UPSs also provide ride-through capability between loss of power and generator startup, ensuring a smooth transition and keeping your business open. The vast majority of data-center administrators protect their servers with some sort of UPS.

IBM Power Systems* offers UPSs in the IBM Configurator for e-business (e-config) as type number 9910. Type 9910 UPSs carry Powerware logos as part of the Eaton Corporation PowerChain Management solutions portfolio. These UPSs range from 950 watts to 8000 watts of usable output power, come in either a stand-alone or rack-mount form factor, and offer extended battery modules on some models for longer run times. You can find complete technical specifications for individual 9910 models at the Powerware IBM UPS Web site (www.powerware.com/ibm).

Communications Options

In general, three communications options are available for use with Power Systems servers: relay, serial and Web/SNMP. Relay communications is defaulted for IBM i but is also available for AIX*, Linux* or a combination in a multiple-partition environment. Relay communications provides a direct link into the server for internal control. Serial communications is another point-to-point option that can be selected when you want to use the UPS vendor-supplied applications. Although these applications include more functionality than relay communications, the serial interface is limited to a single AIX or Linux operating system. Serial isn’t supported with IBM i. Web/SNMP communications allow the UPS to have its own IP address on the network. The behavior is similar to serial, except multiple AIX and Linux operating systems can interact with the UPS. Web/SNMP isn’t supported with IBM i.

The UPSs have either an integrated relay-serial communications port or a relay-serial interface card available as feature code 2939 under type 9910 in e-config. Feature code 2939 includes the communications card, user’s guide, relay cable and serial cable. The relay communications are supported through the FSP as shown in Figure 1.

You don’t have to load any additional hardware, software or applications. Interacting with multiple partitions running independent operating systems is seamless.

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