<s>
In	O
Fibre	B-Architecture
Channel	I-Architecture
protocol	O
,	O
a	O
registered	B-Architecture
state	I-Architecture
change	I-Architecture
notification	I-Architecture
(	O
RSCN	O
)	O
is	O
a	O
Fibre	B-Architecture
Channel	I-Architecture
fabric	I-Architecture
's	O
notification	O
sent	O
to	O
all	O
specified	O
nodes	B-Protocol
in	O
case	O
of	O
any	O
major	O
fabric	O
changes	O
.	O
</s>
<s>
This	O
allows	O
nodes	B-Protocol
to	O
immediately	O
gain	O
knowledge	O
about	O
the	O
fabric	O
and	O
react	O
accordingly	O
.	O
</s>
<s>
Implementation	O
of	O
this	O
function	O
is	O
obligatory	O
for	O
each	O
Fibre	B-Architecture
Channel	I-Architecture
switch	I-Architecture
,	O
but	O
is	O
optional	O
for	O
a	O
node	O
.	O
</s>
<s>
The	O
nodes	B-Protocol
wishing	O
to	O
be	O
notified	O
in	O
such	O
way	O
need	O
to	O
register	O
themselves	O
first	O
at	O
the	O
Fabric	O
Controller	O
,	O
which	O
is	O
a	O
standardized	O
FC	O
virtual	O
address	O
present	O
at	O
each	O
switch	O
.	O
</s>
<s>
If	O
a	O
fabric	O
has	O
some	O
zones	B-Architecture
configured	O
for	O
additional	O
security	O
,	O
notifications	O
do	O
not	O
cross	O
zone	O
boundaries	O
if	O
not	O
needed	O
.	O
</s>
<s>
For	O
example	O
,	O
let	O
's	O
assume	O
there	O
is	O
a	O
fabric	O
with	O
just	O
one	O
node	O
,	O
namely	O
a	O
server	O
's	O
FC-compatible	O
HBA	B-Architecture
.	O
</s>
<s>
Then	O
a	O
human	O
administrator	O
connects	O
another	O
node	O
,	O
like	O
a	O
disk	B-General_Concept
array	I-General_Concept
,	O
to	O
the	O
fabric	O
.	O
</s>
<s>
The	O
switch	O
,	O
however	O
,	O
has	O
a	O
list	O
of	O
registered	O
nodes	B-Protocol
(	O
currently	O
containing	O
only	O
the	O
HBA	B-Architecture
node	O
)	O
and	O
notifies	O
every	O
one	O
of	O
them	O
.	O
</s>
<s>
As	O
the	O
HBA	B-Architecture
receives	O
the	O
notification	O
,	O
it	O
chooses	O
to	O
query	O
the	O
nearest	O
switch	O
about	O
current	O
list	O
of	O
nodes	B-Protocol
.	O
</s>
<s>
It	O
detects	O
a	O
new	O
disk	B-General_Concept
array	I-General_Concept
and	O
starts	O
to	O
communicate	O
with	O
it	O
on	O
a	O
SCSI	B-Architecture
level	O
,	O
asking	O
for	O
a	O
list	O
of	O
SCSI	B-Architecture
LUNs	O
.	O
</s>
<s>
Then	O
it	O
notifies	O
a	O
server	O
's	O
operating	B-General_Concept
system	I-General_Concept
,	O
that	O
there	O
is	O
a	O
new	O
SCSI	B-Architecture
target	O
containing	O
some	O
LUNs	O
.	O
</s>
<s>
The	O
operating	B-General_Concept
system	I-General_Concept
auto-configures	O
those	O
as	O
new	O
block	O
devices	O
,	O
ready	O
for	O
use	O
.	O
</s>
