<s>
Stable	B-General_Concept
storage	I-General_Concept
is	O
a	O
classification	O
of	O
computer	B-General_Concept
data	I-General_Concept
storage	I-General_Concept
technology	O
that	O
guarantees	O
atomicity	B-General_Concept
for	O
any	O
given	O
write	O
operation	O
and	O
allows	O
software	O
to	O
be	O
written	O
that	O
is	O
robust	B-Application
against	O
some	O
hardware	O
and	O
power	O
failures	O
.	O
</s>
<s>
Most	O
computer	O
disk	B-Device
drives	I-Device
are	O
not	O
considered	O
stable	B-General_Concept
storage	I-General_Concept
because	O
they	O
do	O
not	O
guarantee	O
atomic	O
write	O
;	O
an	O
error	O
could	O
be	O
returned	O
upon	O
subsequent	O
read	O
of	O
the	O
disk	O
where	O
it	O
was	O
just	O
written	O
to	O
in	O
lieu	O
of	O
either	O
the	O
new	O
or	O
prior	O
data	O
.	O
</s>
<s>
Writing	O
data	O
to	O
a	O
disk	O
in	O
two	O
places	O
in	O
a	O
specific	O
way	O
is	O
one	O
technique	O
and	O
can	O
be	O
done	O
by	O
application	B-Application
software	I-Application
.	O
</s>
<s>
Most	O
often	O
though	O
,	O
stable	B-General_Concept
storage	I-General_Concept
functionality	O
is	O
achieved	O
by	O
mirroring	B-General_Concept
data	O
on	O
separate	O
disks	O
via	O
RAID	B-Architecture
technology	O
(	O
level	O
1	O
or	O
greater	O
)	O
.	O
</s>
<s>
The	O
RAID	B-Architecture
controller	O
implements	O
the	O
disk	O
writing	O
algorithms	O
that	O
enable	O
separate	O
disks	O
to	O
act	O
as	O
stable	B-General_Concept
storage	I-General_Concept
.	O
</s>
<s>
The	O
RAID	B-Architecture
technique	O
is	O
robust	B-Application
against	O
some	O
single	O
disk	B-Device
failure	I-Device
in	O
an	O
array	O
of	O
disks	O
whereas	O
the	O
software	O
technique	O
of	O
writing	O
to	O
separate	O
areas	O
of	O
the	O
same	O
disk	O
only	O
protects	O
against	O
some	O
kinds	O
of	O
internal	O
disk	O
media	O
failures	O
such	O
as	O
bad	O
sectors	B-Application
in	O
single	O
disk	O
arrangements	O
.	O
</s>
