<s>
Quality-of-Data	B-General_Concept
(	O
QoD	O
)	O
is	O
a	O
designation	O
coined	O
by	O
L	O
.	O
Veiga	O
,	O
that	O
specifies	O
and	O
describes	O
the	O
required	O
Quality	O
of	O
Service	O
of	O
a	O
distributed	O
storage	O
system	O
from	O
the	O
Consistency	O
point	O
of	O
view	O
of	O
its	O
data	O
.	O
</s>
<s>
It	O
can	O
be	O
used	O
to	O
support	O
Big	B-Application
Data	I-Application
management	O
frameworks	O
,	O
Workflow	O
management	O
,	O
and	O
HPC	O
systems	O
(	O
mainly	O
for	O
data	O
replication	O
and	O
consistency	O
)	O
.	O
</s>
<s>
Initially	O
it	O
was	O
based	O
in	O
a	O
model	O
from	O
an	O
existing	O
research	O
work	O
regarding	O
vector-field	O
Consistency	O
,	O
awarded	O
the	O
best-paper	O
prize	O
in	O
the	O
ACM/IFIP/Usenix	O
Middleware	B-General_Concept
Conference	O
2007	O
and	O
later	O
enhanced	O
for	O
increased	O
scalability	O
and	O
fault-tolerance	O
.	O
</s>
<s>
This	O
consistency	O
model	O
has	O
been	O
successfully	O
applied	O
and	O
proven	O
in	O
Big	B-Application
Data	I-Application
key/value	O
store	O
Apache	B-Language
HBase	I-Language
,	O
initially	O
designed	O
as	O
a	O
middleware	B-General_Concept
module	O
seating	O
between	O
clusters	O
from	O
separate	O
data	O
centres	O
.	O
</s>
<s>
The	O
HBase-QoD	O
coupling	O
minimises	O
bandwidth	O
usage	O
and	O
optimises	O
resources	O
allocation	O
during	O
replication	O
achieving	O
the	O
desired	O
consistency	O
level	O
at	O
a	O
more	O
fine-grained	O
level	O
.	O
</s>
