<s>
Disk	B-Operating_System
First	I-Operating_System
Aid	I-Operating_System
is	O
a	O
free	O
software	B-Application
utility	I-Application
made	O
by	O
Apple	O
Inc	O
.	O
that	O
was	O
bundled	O
with	O
all	O
computers	O
running	O
the	O
classic	B-Application
Mac	I-Application
OS	I-Application
.	O
</s>
<s>
This	O
tool	O
verifies	O
and	O
repairs	O
a	O
limited	O
number	O
of	O
directory	B-Application
structure	I-Application
problems	O
on	O
any	O
HFS	B-Application
or	O
HFS	B-Application
Plus	I-Application
hard	B-Device
disk	I-Device
or	O
volume	O
.	O
</s>
<s>
Disk	B-Operating_System
First	I-Operating_System
Aid	I-Operating_System
is	O
a	O
very	O
simple	O
tool	O
,	O
with	O
it	O
only	O
being	O
able	O
to	O
detect	O
and	O
repair	O
directory	B-Application
damage	O
and	O
many	O
books	O
are	O
critical	O
of	O
its	O
sometimes	O
inaccurate	O
reporting	O
of	O
errors	O
,	O
and	O
often	O
suggest	O
to	O
run	O
the	O
tool	O
more	O
than	O
once	O
to	O
ensure	O
a	O
consistent	O
result	O
.	O
</s>
<s>
Disk	B-Operating_System
First	I-Operating_System
Aid	I-Operating_System
is	O
located	O
in	O
Applications:Utilities:Disk	O
First	O
Aid	O
.	O
</s>
<s>
The	O
classic	B-Application
Mac	I-Application
OS	I-Application
provides	O
an	O
option	O
to	O
run	O
Disk	B-Operating_System
First	I-Operating_System
Aid	I-Operating_System
on	O
startup	O
,	O
although	O
it	O
has	O
been	O
reported	O
that	O
it	O
provides	O
little	O
gain	O
and	O
sometimes	O
can	O
amplify	O
a	O
problem	O
.	O
</s>
<s>
Its	O
capabilities	O
were	O
incorporated	O
into	O
Disk	B-Application
Utility	I-Application
in	O
macOS	B-Application
.	O
</s>
<s>
One	O
source	O
suggests	O
that	O
disk	B-Application
utility	I-Application
should	O
be	O
used	O
when	O
there	O
are	O
:	O
</s>
<s>
Frequent	O
system	B-General_Concept
crashes	I-General_Concept
,	O
</s>
<s>
Disk	B-Operating_System
First	I-Operating_System
Aid	I-Operating_System
has	O
built-in	O
capabilities	O
to	O
check	O
for	O
damage	O
to	O
:	O
</s>
<s>
Partition	B-Application
Map	I-Application
,	O
</s>
<s>
Device	B-Application
Driver	I-Application
,	O
</s>
<s>
Boot	B-Device
Blocks	I-Device
,	O
</s>
<s>
Master	O
Directory	B-Application
Block	O
,	O
</s>
<s>
After	O
analyzing	O
the	O
disk	O
directory	B-Application
,	O
Disk	B-Operating_System
First	I-Operating_System
Aid	I-Operating_System
determines	O
whether	O
it	O
is	O
able	O
to	O
repair	O
any	O
damage	O
that	O
was	O
detected	O
.	O
</s>
