protocol-independent manner. See also
worldwide node name
write hit
A write operation in which the requested
data is in the cache.
write penalty
The performance impact of a classical
RAID-5 write operation.
WWNN
See worldwide node name.
WWPN

See worldwide port name.

X
xSeries
The product name of an IBM e(logo)server
product that emphasizes industry-standard
server scalability and self-managing server
technologies. It is the successor to the

Netfinity family of servers.

Z
z/Architecture
An IBM architecture for mainframe
computers and peripherals. The IBM
e(logo)server zSeries family of servers
uses the z/Architecture architecture. It is
the successor to the S/390 and 9672
family of servers. See also iSeries.

z/OS An operating system for the IBM

e(logo)server product line that supports
64-bit real storage.
z/OS Global Mirror
A function of a storage server that assists
a control program to maintain a consistent
copy of a logical volume on another
storage unit. All modifications of the
primary logical volume by any attached
host are presented in order to a single
host. The host then makes these
modifications on the secondary logical
volume. This function was formerly called
extended remote copy or XRC.
zSeries
An IBM e(logo)server family of servers
that emphasizes near-zero downtime.
IBM enterprise servers based on
z/Architecture.
zSeries storage
Storage arrays and logical volumes that
are defined in the DS8000 as connected

to zSeries servers.

352 IBM TotalStorage DS8000: Messages Reference