<s>
In	O
computing	O
,	O
System	B-Application
Fault	I-Application
Tolerance	I-Application
(	O
SFT	O
)	O
is	O
a	O
fault	B-General_Concept
tolerant	I-General_Concept
system	I-General_Concept
built	O
into	O
NetWare	B-Operating_System
operating	B-General_Concept
systems	I-General_Concept
.	O
</s>
<s>
Three	O
levels	O
of	O
fault	B-General_Concept
tolerance	I-General_Concept
exist	O
:	O
</s>
<s>
SFT	O
II	O
provides	O
a	O
disk	B-General_Concept
mirroring	I-General_Concept
or	O
duplexing	O
system	O
based	O
on	O
RAID	B-Architecture
1	O
;	O
mirroring	O
refers	O
to	O
two	O
disk	O
drives	O
holding	O
the	O
same	O
data	O
,	O
duplexing	O
uses	O
two	O
data	O
channels/controllers	O
to	O
connect	O
the	O
disks	O
(	O
fault	B-General_Concept
tolerance	I-General_Concept
on	O
the	O
disk	O
level	O
and	O
optionally	O
on	O
the	O
data-channel	O
level	O
)	O
.	O
</s>
<s>
SFT	O
III	O
is	O
a	O
server	B-Application
duplexing	O
scheme	O
where	O
if	O
a	O
server	B-Application
fails	O
,	O
a	O
constantly	O
synchronized	O
server	B-Application
seamlessly	O
takes	O
its	O
place	O
(	O
fault	B-General_Concept
tolerance	I-General_Concept
on	O
the	O
system	O
level	O
)	O
.	O
</s>
