<s>
Extended	B-Device
Remote	I-Device
Copy	I-Device
or	O
XRC	O
is	O
an	O
IBM	O
zSeries	O
and	O
System	B-Device
z9	I-Device
mainframe	B-Architecture
computer	I-Architecture
technology	O
for	O
data	B-Architecture
replication	I-Architecture
.	O
</s>
<s>
It	O
combines	O
supported	O
hardware	O
and	O
z/OS	B-Application
software	O
to	O
provide	O
asynchronous	O
replication	B-Architecture
over	O
long	O
distances	O
.	O
</s>
<s>
It	O
is	O
complementary	O
to	O
IBM	O
's	O
Peer	B-Device
to	I-Device
Peer	I-Device
Remote	I-Device
Copy	I-Device
(	O
PPRC	O
)	O
service	O
,	O
which	O
is	O
designed	O
to	O
operate	O
either	O
synchronously	O
or	O
asynchronously	O
over	O
shorter	O
distances	O
.	O
</s>
<s>
XRC	O
as	O
a	O
z/OS	B-Application
copy	O
services	O
solution	O
can	O
be	O
compared	O
to	O
Global	B-Application
Mirror	I-Application
for	O
ESS	O
,	O
which	O
is	O
a	O
controller-based	O
solution	O
for	O
either	O
the	O
open	O
systems	O
or	O
z/Series	O
environments	O
.	O
</s>
<s>
Both	O
Global	B-Application
Mirror	I-Application
for	O
ESS	O
(	O
Asynchronous	O
PPRC	O
)	O
and	O
XRC	O
(	O
Global	B-Application
Mirror	I-Application
for	O
z/Series	O
)	O
are	O
asynchronous	O
replication	B-Architecture
technologies	O
,	O
although	O
their	O
implementations	O
are	O
somewhat	O
different	O
.	O
</s>
<s>
Extended	B-Device
Remote	I-Device
Copy	I-Device
or	O
XRC	O
is	O
now	O
known	O
as	O
Global	B-Application
Mirror	I-Application
for	O
z/Series	O
(	O
XRC	O
)	O
.	O
</s>
<s>
It	O
keeps	O
the	O
data	O
time	O
consistent	O
across	O
multiple	O
ESS	O
(	O
Enterprise	B-Device
Storage	I-Device
Server	I-Device
)	O
or	O
HDS	O
(	O
Hitachi	O
Data	O
Systems	O
)	O
disk	O
subsystems	O
at	O
the	O
recovery	O
site	O
.	O
</s>
<s>
XRC	O
functions	O
as	O
a	O
combination	O
of	O
disk	O
(	O
IBM	B-Device
ESS	I-Device
or	O
HDS	O
licensed	O
)	O
Microcode	O
and	O
application	O
code	O
running	O
on	O
a	O
z/Series	O
host	O
and	O
provides	O
a	O
recovery	O
point	O
that	O
is	O
time	O
consistent	O
across	O
multiple	O
disk	O
subsystems	O
.	O
</s>
