NonStop NS2400 Series Planning Guide

SAS Disk Enclosures With a Rack-Mounted UPS
In this supported configuration, only SAS Disk Enclosures are protected by the rack-mounted UPS.
The rack(s) with SAS Disk Enclosures and/or Storage CLIMs are supported by one or more
rack-mounted UPS.
Figure 58 shows an example of a supported configuration in a NonStop system with the left PDUs
connected to the rack-mounted UPS, and the right PDUs connected to the utility power. The
rack-mounted UPS is connected to the utility power.
Figure 58 SAS Disk Enclosures With a Rack-Mounted UPS
When the utility power fails, the NonStop system powers off without an OSM-initiated controlled
shutdown of the I/O operations and processors. Only the products in the rack with the rack-mounted
UPS remain powered on. All completed disk write transactions’ data are written to the disk drive
media or the disk drive write cache. The rack-mounted UPS provides the extended time for the disk
drives to transfer the data from their write cache to the media. The rack-mounted UPS provides
extended time for the disk drives to transfer the data from their write cache to the media preventing
loss of data.
192 UPS and Data Center Power Configurations