<s>
An	O
AG	B-Application
or	O
allocation	B-Application
group	I-Application
is	O
a	O
subvolume	O
in	O
a	O
file	B-Application
system	I-Application
which	O
maintains	O
its	O
own	O
track	O
of	O
free	O
blocks	O
and	O
file	O
data	O
.	O
</s>
<s>
This	O
makes	O
simultaneous	O
file	O
operations	O
possible	O
;	O
only	O
one	O
write	O
can	O
happen	O
to	O
an	O
AG	B-Application
at	O
any	O
time	O
,	O
but	O
multiple	O
operations	O
can	O
be	O
performed	O
on	O
the	O
file	B-Application
system	I-Application
,	O
each	O
happening	O
in	O
a	O
different	O
AG	B-Application
.	O
</s>
<s>
In	O
SMP	B-Operating_System
systems	O
,	O
multiple	O
CPUs	O
can	O
write	O
to	O
different	O
AGs	B-Application
,	O
enabling	O
physically	O
concurrent	O
disk	O
operations	O
on	O
a	O
single	O
file	B-Application
system	I-Application
.	O
</s>
<s>
Whereas	O
a	O
single	O
hard	B-Device
disk	I-Device
is	O
not	O
capable	O
of	O
reading	O
or	O
writing	O
to	O
multiple	O
places	O
simultaneously	O
,	O
a	O
file	B-Application
system	I-Application
or	O
partition	O
that	O
utilizes	O
a	O
scheme	O
such	O
as	O
RAID	B-Architecture
or	O
logical	B-Application
volume	I-Application
management	I-Application
may	O
encompass	O
multiple	O
physical	O
disks	O
.	O
</s>
<s>
In	O
this	O
case	O
,	O
the	O
use	O
of	O
allocation	B-Application
groups	I-Application
may	O
grant	O
additional	O
file	B-Application
system	I-Application
throughput	O
.	O
</s>
<s>
Allocation	B-Application
groups	I-Application
are	O
used	O
by	O
these	O
file	B-Application
systems	I-Application
:	O
</s>
