<s>
Geo-replication	B-General_Concept
systems	O
are	O
designed	O
to	O
provide	O
improved	O
availability	O
and	O
disaster	O
tolerance	O
by	O
using	O
geographically	O
distributed	O
data	O
centers	O
.	O
</s>
<s>
Geo-replication	B-General_Concept
can	O
be	O
achieved	O
using	O
software	O
,	O
hardware	O
or	O
a	O
combination	O
of	O
the	O
two	O
.	O
</s>
<s>
Geo-replication	B-General_Concept
software	O
is	O
a	O
network	O
performance-enhancing	O
technology	O
that	O
is	O
designed	O
to	O
provide	O
improved	O
access	O
to	O
portal	O
or	O
intranet	B-General_Concept
content	O
for	O
uses	O
at	O
the	O
most	O
remote	O
parts	O
of	O
large	O
organizations	O
.	O
</s>
<s>
It	O
is	O
based	O
on	O
the	O
principle	O
of	O
storing	O
complete	O
replicas	O
of	O
portal	O
content	O
on	O
local	O
servers	O
,	O
and	O
then	O
keeping	O
the	O
content	O
on	O
those	O
servers	O
up-to-date	O
using	O
heavily	O
compressed	B-General_Concept
data	I-General_Concept
updates	O
.	O
</s>
<s>
Geo-replication	B-General_Concept
technologies	O
are	O
used	O
to	O
provide	O
replication	O
of	O
the	O
content	O
of	O
portals	O
,	O
intranets	B-General_Concept
,	O
web	B-Application
applications	I-Application
,	O
content	O
and	O
data	O
between	O
servers	O
,	O
across	O
wide	O
area	O
networks	O
WAN	O
to	O
allow	O
users	O
at	O
remote	O
sites	O
to	O
access	O
central	O
content	O
at	O
LAN	B-General_Concept
speeds	O
.	O
</s>
<s>
Geo-replication	B-General_Concept
software	O
can	O
improve	O
the	O
performance	O
of	O
data	O
networks	O
that	O
suffer	O
limited	O
bandwidth	O
,	O
latency	O
and	O
periodic	O
disconnection	O
.	O
</s>
<s>
Terabytes	O
of	O
data	O
can	O
be	O
replicated	O
over	O
a	O
wide	O
area	O
network	O
,	O
giving	O
remote	O
sites	O
faster	O
access	O
to	O
web	B-Application
applications	I-Application
.	O
</s>
<s>
Geo-replication	B-General_Concept
software	O
uses	O
a	O
combination	O
of	O
data	B-General_Concept
compression	I-General_Concept
and	O
content	O
caching	B-Protocol
technologies	O
.	O
</s>
<s>
differencing	B-Algorithm
technologies	O
can	O
also	O
be	O
employed	O
to	O
reduce	O
the	O
volume	O
of	O
data	O
that	O
has	O
to	O
be	O
transmitted	O
to	O
keep	O
portal	O
content	O
accurate	O
across	O
all	O
servers	O
.	O
</s>
<s>
Geo-replication	B-General_Concept
technology	O
is	O
deployed	O
to	O
accelerate	O
the	O
remote	O
end	O
user	O
portal	O
performance	O
to	O
be	O
equivalent	O
to	O
that	O
experienced	O
by	O
users	O
locally	O
accessing	O
the	O
portal	O
in	O
the	O
central	O
office	O
.	O
</s>
<s>
To	O
deliver	O
this	O
reduction	O
in	O
the	O
size	O
of	O
the	O
required	O
data	O
updates	O
across	O
a	O
portal	O
,	O
geo-replication	B-General_Concept
systems	O
often	O
use	O
differencing	B-Algorithm
engine	O
technologies	O
.	O
</s>
<s>
This	O
type	O
of	O
differencing	B-Algorithm
system	O
ensures	O
that	O
no	O
content	O
,	O
at	O
the	O
byte	O
level	O
,	O
is	O
ever	O
sent	O
to	O
a	O
server	O
twice	O
.	O
</s>
<s>
Geo-replication	B-General_Concept
systems	O
are	O
often	O
extended	O
to	O
deliver	O
local	O
replication	O
beyond	O
the	O
server	O
and	O
down	O
to	O
the	O
laptop	O
used	O
by	O
a	O
single	O
user	O
.	O
</s>
