<s>
A	O
SCSI	B-Protocol
connector	I-Protocol
(	O
)	O
is	O
used	O
to	O
connect	O
computer	O
parts	O
that	O
use	O
a	O
system	O
called	O
SCSI	B-Architecture
to	O
communicate	O
with	O
each	O
other	O
.	O
</s>
<s>
SCSI	B-Protocol
connectors	I-Protocol
can	O
be	O
electrical	B-Protocol
connectors	I-Protocol
or	O
optical	B-Device
connectors	I-Device
.	O
</s>
<s>
There	O
have	O
been	O
a	O
large	O
variety	O
of	O
SCSI	B-Protocol
connectors	I-Protocol
in	O
use	O
at	O
one	O
time	O
or	O
another	O
in	O
the	O
computer	O
industry	O
.	O
</s>
<s>
Twenty-five	O
years	O
of	O
evolution	O
and	O
three	O
major	O
revisions	O
of	O
the	O
standards	O
resulted	O
in	O
requirements	O
for	O
Parallel	O
SCSI	B-Protocol
connectors	I-Protocol
that	O
could	O
handle	O
an	O
8	O
,	O
16	O
or	O
32	O
bit	O
wide	O
bus	B-General_Concept
running	O
at	O
5	O
,	O
10	O
or	O
20	O
megatransfer/s	O
,	O
with	O
conventional	O
or	O
differential	O
signaling	O
.	O
</s>
<s>
Serial	O
SCSI	B-Architecture
added	O
another	O
three	O
transport	O
types	O
,	O
each	O
with	O
one	O
or	O
more	O
connector	O
types	O
.	O
</s>
<s>
SCSI	B-Architecture
makes	O
use	O
of	O
cables	O
to	O
connect	O
devices	O
.	O
</s>
<s>
In	O
a	O
typical	O
example	O
,	O
a	O
socket	O
on	O
a	O
computer	B-Device
motherboard	I-Device
would	O
have	O
one	O
end	O
of	O
a	O
cable	O
plugged	O
into	O
it	O
,	O
while	O
the	O
other	O
end	O
of	O
the	O
cable	O
plugged	O
into	O
a	O
disk	O
drive	O
or	O
other	O
device	O
.	O
</s>
<s>
For	O
example	O
,	O
"	O
CN36	O
"	O
(	O
also	O
written	O
"	O
CN-36	O
"	O
or	O
"	O
CN36	O
"	O
)	O
would	O
be	O
a	O
36-pin	O
Centronics-style	B-Device
connector	I-Device
.	O
</s>
<s>
For	O
some	O
connectors	O
(	O
such	O
as	O
the	O
D-subminiature	B-Protocol
family	O
)	O
use	O
of	O
the	O
hyphen	O
or	O
space	O
is	O
more	O
common	O
,	O
for	O
others	O
(	O
like	O
the	O
"	O
DD50	O
"	O
)	O
less	O
so	O
.	O
</s>
<s>
Parallel	O
SCSI	B-Architecture
(	O
SCSI	B-Architecture
Parallel	O
Interface	O
SPI	O
)	O
allows	O
for	O
attachment	O
of	O
up	O
to	O
8	O
devices	O
(	O
8-bit	O
Narrow	O
SCSI	B-Architecture
)	O
or	O
16	O
devices	O
(	O
16-bit	O
Wide	O
SCSI	B-Architecture
)	O
to	O
the	O
SCSI	B-Architecture
bus	B-General_Concept
.	O
</s>
<s>
The	O
SCSI	B-Architecture
Host	B-Architecture
controller	I-Architecture
takes	O
up	O
one	O
slot	O
on	O
the	O
SCSI	B-Architecture
bus	B-General_Concept
,	O
which	O
limits	O
the	O
number	O
of	O
devices	O
allowed	O
on	O
the	O
bus	B-General_Concept
to	O
7	O
or	O
15	O
devices	O
respectively	O
.	O
</s>
<s>
SCSI	B-Architecture
Host	B-Architecture
Controllers	I-Architecture
may	O
have	O
multiple	O
SCSI	B-Architecture
buses	O
(	O
e.g.	O
</s>
<s>
Adaptec	O
AHA-2940	O
)	O
to	O
allow	O
more	O
SCSI	B-Architecture
devices	O
to	O
be	O
attached	O
.	O
</s>
<s>
Early	O
generations	O
of	O
SCSI	B-Architecture
hard	B-Device
drive	I-Device
assemblies	I-Device
generally	O
had	O
two	O
connectors	O
(	O
power	O
and	O
communication	O
)	O
.	O
</s>
<s>
The	O
communication	O
connectors	O
on	O
the	O
drives	O
were	O
usually	O
a	O
50	O
(	O
for	O
8-bit	O
SCSI	B-Architecture
)	O
or	O
68	O
pin	O
male	O
(	O
for	O
16-bit	O
SCSI	B-Architecture
)	O
"	O
IDC	B-Protocol
header	B-Protocol
"	O
which	O
has	O
two	O
rows	O
of	O
pins	O
,	O
0.1inches	O
apart	O
.	O
</s>
<s>
This	O
type	O
of	O
header	B-Protocol
was	O
used	O
in	O
a	O
typical	O
desktop	O
PC	O
until	O
around	O
2010	O
,	O
including	O
the	O
40-pin	O
(	O
two	O
rows	O
of	O
20	O
)	O
version	O
used	O
for	O
ATA	B-Protocol
fixed	O
and	O
optical	O
disk	O
drives	O
.	O
</s>
<s>
In	O
most	O
cases	O
,	O
the	O
host	B-Architecture
adapter	I-Architecture
would	O
have	O
a	O
similar	O
header-style	O
connection	O
.	O
</s>
<s>
In	O
some	O
cases	O
,	O
though	O
,	O
the	O
host	B-Architecture
adapter	I-Architecture
end	O
of	O
the	O
cable	O
would	O
use	O
a	O
different	O
connector	O
.	O
</s>
<s>
For	O
example	O
,	O
in	O
the	O
Sun	O
260	O
series	O
chassis	O
(	O
used	O
for	O
the	O
Sun	B-Device
3/260	I-Device
and	O
Sun	B-Device
4/260	I-Device
computers	O
)	O
,	O
the	O
connector	O
was	O
the	O
same	O
3-row	O
96-pin	O
connector	O
used	O
to	O
attach	O
peripheral	O
cards	O
to	O
the	O
VMEbus	B-Architecture
backplane	B-Architecture
.	O
</s>
<s>
Most	O
late	O
parallel	O
SCSI	B-Architecture
disk-drives	O
utilize	O
an	O
80-pin	O
SCA	O
(	O
Single	O
Connector	O
Attachment	O
)	O
connector	O
.	O
</s>
<s>
This	O
connector	O
includes	O
a	O
power	O
connection	O
and	O
also	O
has	O
long	O
and	O
short	O
pins	O
which	O
enable	O
hot	B-Device
swapping	I-Device
.	O
</s>
<s>
Note	O
that	O
this	O
connector	O
is	O
primarily	O
found	O
on	O
disk	O
drive	O
HDAs	B-Device
(	O
and	O
of	O
course	O
the	O
mating	O
enclosure	O
backplane	B-Architecture
connector	O
)	O
.	O
</s>
<s>
As	O
with	O
everything	O
SCSI	B-Architecture
,	O
there	O
are	O
exceptions	O
.	O
</s>
<s>
Standardization	O
was	O
perhaps	O
less	O
consistent	O
in	O
the	O
early	O
days	O
of	O
SCSI	B-Architecture
manufacture	O
.	O
</s>
<s>
Early	O
SCSI	B-Architecture
interfaces	O
commonly	O
used	O
a	O
50-pin	O
micro	B-Protocol
ribbon	I-Protocol
connector	I-Protocol
.	O
</s>
<s>
This	O
connector	O
is	O
similar	O
to	O
the	O
36-pin	O
connector	O
used	O
by	O
Centronics	O
for	O
the	O
parallel	O
interface	O
on	O
their	O
printers	O
,	O
thus	O
the	O
connector	O
became	O
popularly	O
known	O
as	O
"	O
Centronics	O
SCSI	B-Architecture
"	O
or	O
"	O
CN-50	O
"	O
.	O
</s>
<s>
It	O
is	O
also	O
referred	O
to	O
as	O
a	O
"	O
SCSI-1	O
connector	O
"	O
;	O
since	O
many	O
connectors	O
have	O
been	O
used	O
for	O
SCSI-1	O
,	O
this	O
can	O
be	O
confusing	O
.	O
</s>
<s>
Apple	O
used	O
DB-25	B-Protocol
connectors	I-Protocol
,	O
which	O
,	O
having	O
only	O
25	O
pins	O
rather	O
than	O
50	O
,	O
</s>
<s>
Furthermore	O
,	O
DB-25s	B-Protocol
were	O
commonly	O
used	O
for	O
RS-232	O
serial	O
cables	O
and	O
also	O
to	O
connect	O
parallel	O
printers	O
,	O
meaning	O
that	O
users	O
might	O
accidentally	O
try	O
to	O
use	O
completely	O
inappropriate	O
cables	O
,	O
since	O
the	O
printer	O
and	O
serial	O
cables	O
would	O
fit	O
the	O
connector	O
properly	O
and	O
be	O
hard	O
to	O
visually	O
distinguish	O
.	O
</s>
<s>
Sun	O
Microsystems	O
and	O
Data	O
General	O
used	O
a	O
50-pin	O
3-row	O
DD-50	B-Protocol
connector	O
,	O
which	O
was	O
sometimes	O
incorrectly	O
called	O
a	O
"	O
DB-50	O
"	O
or	O
"	O
HDB-50	O
"	O
.	O
</s>
<s>
Sun	O
also	O
used	O
DB-25s	B-Protocol
on	O
a	O
few	O
products	O
.	O
</s>
<s>
This	O
connector	O
looks	O
like	O
it	O
would	O
be	O
a	O
high	O
density	O
Wide	O
SCSI-2	O
connector	O
,	O
but	O
is	O
actually	O
8-bit	O
SCSI-1	O
.	O
</s>
<s>
Apple	B-Device
Macintosh	I-Device
laptops	O
used	O
a	O
squarish	O
external	O
SCSI	B-Protocol
connector	I-Protocol
called	O
an	O
HDI-30	O
(	O
High	O
Density	O
Interconnect	B-General_Concept
)	O
on	O
the	O
laptop	O
itself	O
(	O
not	O
on	O
the	O
peripheral	O
end	O
of	O
the	O
cable	O
,	O
unless	O
two	O
laptops	O
were	O
being	O
connected	O
)	O
.	O
</s>
<s>
These	O
machines	O
also	O
had	O
the	O
interesting	O
ability	O
to	O
become	O
"	O
SCSI	B-Operating_System
slaves	I-Operating_System
"	O
(	O
officially	O
known	O
as	O
"	O
SCSI	B-Device
Disk	I-Device
Mode	I-Device
"	O
in	O
Apple	O
documentation	O
)	O
,	O
meaning	O
that	O
they	O
could	O
appear	O
to	O
be	O
disk	O
drives	O
when	O
attached	O
to	O
another	O
computer	O
's	O
SCSI	B-Architecture
controller	O
(	O
a	O
feature	O
later	O
reimplemented	O
over	O
FireWire	B-Protocol
and	O
Thunderbolt	B-Protocol
for	O
later	O
,	O
non-SCSI	O
Mac	B-Device
hardware	O
)	O
.	O
</s>
<s>
IBM	O
's	O
early	O
RS6000	B-Device
workstations	O
sometimes	O
used	O
a	O
"	O
High	O
Density	O
Centronics	O
"	O
connector	O
,	O
which	O
was	O
a	O
Centronics-style	B-Device
connector	I-Device
with	O
smaller	O
pins	O
and	O
shell	O
.	O
</s>
<s>
Certain	O
Japanese	O
digital	O
camera	O
manufacturers	O
wanted	O
to	O
put	O
SCSI	B-Architecture
into	O
their	O
equipment	O
,	O
but	O
conventional	O
connectors	O
would	O
have	O
been	O
too	O
large	O
.	O
</s>
<s>
Like	O
IBM	O
,	O
they	O
used	O
a	O
miniaturized	O
Centronics	B-Device
connector	I-Device
,	O
but	O
this	O
one	O
had	O
50	O
pins	O
,	O
and	O
was	O
called	O
the	O
"	O
HPCN50	O
"	O
.	O
</s>
<s>
Some	O
manufacturers	O
used	O
a	O
DC-37	B-Protocol
connector	O
,	O
often	O
incorrectly	O
referred	O
to	O
as	O
a	O
DB-37	B-Protocol
.	O
</s>
<s>
These	O
will	O
most	O
commonly	O
be	O
seen	O
on	O
three-cable	O
systems	O
,	O
which	O
are	O
typically	O
16-bit	O
or	O
32-bit	O
"	O
Wide	O
SCSI	B-Architecture
"	O
systems	O
.	O
</s>
<s>
Extra	O
confusion	O
is	O
generated	O
here	O
since	O
this	O
connector	O
was	O
also	O
frequently	O
used	O
with	O
SMD	B-Architecture
disk	O
drives	O
,	O
which	O
are	O
completely	O
incompatible	O
with	O
SCSI	B-Architecture
drives	O
.	O
</s>
<s>
With	O
the	O
arrival	O
of	O
SCSI-2	O
,	O
the	O
situation	O
was	O
a	O
bit	O
less	O
chaotic	O
.	O
</s>
<s>
For	O
narrow	O
SCSI	B-Architecture
,	O
most	O
manufacturers	O
used	O
the	O
MD50	O
,	O
also	O
sometimes	O
referred	O
to	O
as	O
a	O
Micro	O
DB50	O
,	O
High	O
Density	O
or	O
HD50	O
,	O
Half-Pitch	O
or	O
HP50	O
,	O
or	O
MiniHonda	O
.	O
</s>
<s>
For	O
Wide	O
SCSI-2	O
,	O
the	O
most	O
common	O
connector	O
was	O
the	O
larger	O
sibling	O
of	O
the	O
MD50	O
,	O
known	O
as	O
the	O
MD68	O
,	O
HD68	O
,	O
MiniD68	O
,	O
or	O
HPDB68	O
.	O
</s>
<s>
As	O
time	O
went	O
on	O
,	O
some	O
manufacturers	O
desired	O
connectors	O
even	O
smaller	O
than	O
the	O
SCSI-2	O
connector	O
.	O
</s>
<s>
One	O
such	O
in	O
somewhat	O
common	O
use	O
was	O
the	O
VHDCI	B-Protocol
(	O
Very	B-Protocol
High	I-Protocol
Density	I-Protocol
Cable	I-Protocol
Interconnect	I-Protocol
)	O
connector	O
,	O
also	O
known	O
as	O
an	O
"	O
AMP	O
HPCN68M	O
"	O
(	O
a	O
manufacturer	O
part	O
number	O
)	O
,	O
and	O
sometimes	O
as	O
"	O
SCSI-5	O
"	O
.	O
</s>
<s>
This	O
connector	O
is	O
reputed	O
to	O
suffer	O
fewer	O
bent	O
pins	O
than	O
the	O
68-pin	O
SCSI-2	O
connector	O
despite	O
its	O
minuscule	O
pins	O
.	O
</s>
<s>
There	O
are	O
adapters	O
between	O
most	O
types	O
of	O
parallel	O
SCSI	B-Protocol
connector	I-Protocol
,	O
and	O
some	O
companies	O
will	O
manufacture	O
custom	O
cables	O
to	O
guarantee	O
having	O
the	O
correct	O
connectors	O
.	O
</s>
<s>
Different	O
SCSI	B-Architecture
standards	O
use	O
the	O
same	O
SCSI	B-Protocol
connectors	I-Protocol
as	O
in	O
HVD	O
and	O
LVD	O
SCSI	B-Architecture
(	O
High	O
Voltage	O
Differential	O
and	O
Low	B-Architecture
Voltage	I-Architecture
Differential	I-Architecture
)	O
.	O
</s>
<s>
HVD	O
uses	O
15V	O
while	O
LVD	O
uses	O
3.3V	O
,	O
so	O
connecting	O
an	O
HVD	O
device	O
to	O
an	O
LVD	O
host	B-Architecture
bus	I-Architecture
adaptor	I-Architecture
can	O
blow	O
the	O
line	O
drivers	O
on	O
the	O
HBA	O
,	O
likewise	O
an	O
HVD	O
HBA	O
connected	O
to	O
an	O
LVD	O
device	O
.	O
</s>
<s>
Similarly	O
,	O
connecting	O
a	O
(	O
slow	O
)	O
SE	O
single-ended	O
device	O
onto	O
a	O
(	O
fast	O
)	O
LVD	O
SCSI	B-Architecture
chain	O
will	O
cause	O
the	O
HBA	O
to	O
sync	O
down	O
to	O
the	O
lowest	O
speed	O
.	O
</s>
<s>
Many	O
manufacturers	O
have	O
devised	O
systems	O
in	O
which	O
a	O
SCSI	B-Architecture
disk	O
drive	O
or	O
other	O
device	O
was	O
placed	O
in	O
a	O
small	O
"	O
caddy	O
"	O
container	O
(	O
also	O
called	O
a	O
"	O
drive	O
sled	O
"	O
)	O
,	O
which	O
carried	O
connections	O
for	O
both	O
power	O
and	O
data	O
.	O
</s>
<s>
Some	O
of	O
these	O
systems	O
allowed	O
for	O
hot	B-Device
swap	I-Device
(	O
drives	O
could	O
be	O
replaced	O
with	O
the	O
system	O
running	O
)	O
,	O
while	O
others	O
allowed	O
"	O
warm	B-Device
swap	I-Device
"	O
,	O
in	O
which	O
the	O
SCSI	B-Architecture
bus	B-General_Concept
was	O
"	O
quiesced	O
"	O
(	O
meaning	O
all	O
drive	O
activity	O
was	O
stopped	O
)	O
but	O
remained	O
powered	O
on	O
with	O
devices	O
ready	O
.	O
</s>
<s>
Compaq	O
also	O
made	O
a	O
drive	O
caddy	O
system	O
for	O
the	O
Proliant	B-Device
line	O
of	O
servers	O
.	O
</s>
<s>
Compaq	O
purchased	O
DEC	O
,	O
and	O
Hewlett-Packard	O
later	O
purchased	O
Compaq	O
,	O
and	O
the	O
Proliant	B-Device
and	O
StorageWorks	O
names	O
were	O
reused	O
on	O
other	O
storage	O
products	O
,	O
including	O
later	O
hot-swap	B-Device
systems	O
.	O
</s>
<s>
Single	O
Connector	O
Attachment	O
,	O
or	O
SCA	O
,	O
is	O
a	O
type	O
of	O
connection	O
for	O
the	O
internal	O
cabling	O
of	O
Parallel	O
SCSI	B-Architecture
systems	O
.	O
</s>
<s>
There	O
are	O
two	O
versions	O
of	O
this	O
connector	O
:	O
the	O
SCA-1	O
,	O
which	O
is	O
deprecated	O
,	O
and	O
SCA-2	B-Architecture
,	O
which	O
is	O
the	O
most	O
recent	O
standard	O
.	O
</s>
<s>
In	O
addition	O
there	O
are	O
Single-Ended	O
(	O
SE	O
)	O
and	O
Low	B-Architecture
Voltage	I-Architecture
Differential	I-Architecture
(	O
LVD	O
)	O
types	O
of	O
the	O
SCA	O
.	O
</s>
<s>
SCA	O
is	O
no	O
longer	O
in	O
widespread	O
use	O
,	O
having	O
been	O
superseded	O
by	O
Serial	O
attached	O
SCSI	B-Architecture
.	O
</s>
<s>
Since	O
hard	B-Device
disk	I-Device
drives	I-Device
are	O
among	O
the	O
components	O
of	O
a	O
server	O
computer	O
that	O
are	O
the	O
most	O
likely	O
to	O
fail	O
,	O
there	O
has	O
always	O
been	O
demand	O
for	O
the	O
ability	O
to	O
replace	O
a	O
faulty	O
drive	O
without	O
having	O
to	O
shut	O
down	O
the	O
whole	O
system	O
.	O
</s>
<s>
This	O
technique	O
is	O
called	O
hot-swapping	B-Device
and	O
is	O
one	O
of	O
the	O
main	O
motivations	O
behind	O
the	O
development	O
of	O
SCA	O
.	O
</s>
<s>
In	O
connection	O
with	O
RAID	B-Architecture
,	O
for	O
example	O
,	O
this	O
allows	O
for	O
seamless	O
replacement	O
of	O
failed	O
drives	O
.	O
</s>
<s>
Normally	O
,	O
hard	B-Device
disk	I-Device
drives	I-Device
make	O
use	O
of	O
two	O
cables	O
:	O
one	O
for	O
data	O
and	O
one	O
for	O
power	O
,	O
and	O
they	O
also	O
have	O
their	O
specific	O
parameters	O
(	O
SCSI	B-Architecture
ID	O
etc	O
.	O
)	O
</s>
<s>
to	O
be	O
set	O
using	O
jumpers	B-Device
on	O
each	O
drive	O
.	O
</s>
<s>
Drives	O
employing	O
SCA	O
have	O
only	O
one	O
plug	O
which	O
carries	O
both	O
data	O
and	O
power	O
and	O
also	O
allows	O
them	O
to	O
receive	O
their	O
configuration	O
parameters	O
from	O
the	O
SCSI	B-Architecture
backplane	B-Architecture
.	O
</s>
<s>
The	O
SCA	O
connector	O
for	O
parallel	O
SCSI	B-Architecture
drives	O
has	O
80	O
pins	O
,	O
as	O
opposed	O
to	O
the	O
68	O
pin	O
interface	O
found	O
on	O
most	O
modern	O
parallel	O
SCSI	B-Architecture
drives	O
.	O
</s>
<s>
To	O
make	O
better	O
use	O
of	O
their	O
hot-plugging	B-Device
capability	O
,	O
SCA	O
drives	O
usually	O
are	O
installed	O
into	O
drive	B-Device
bays	I-Device
into	O
which	O
they	O
slide	O
with	O
ease	O
.	O
</s>
<s>
At	O
the	O
far	O
end	O
of	O
these	O
bays	O
is	O
the	O
backplane	B-Architecture
of	O
the	O
SCSI	B-Architecture
subsystem	O
located	O
with	O
a	O
connector	O
that	O
plugs	B-Protocol
into	O
the	O
drive	O
automatically	O
when	O
it	O
is	O
inserted	O
.	O
</s>
<s>
Full	O
hot-swappable	B-Device
functionality	O
still	O
requires	O
the	O
support	O
of	O
other	O
software	O
and	O
hardware	O
components	O
of	O
the	O
system	O
.	O
</s>
<s>
In	O
particular	O
the	O
operating	O
system	O
and	O
RAID	B-Architecture
layers	O
will	O
need	O
hot-swap	B-Device
support	O
to	O
enable	O
hard	B-Device
drive	I-Device
hot-swapping	B-Device
to	O
be	O
carried	O
out	O
without	O
shutting	O
down	O
the	O
system	O
.	O
</s>
<s>
Serial	O
SCSI	B-Architecture
disk-drives	O
use	O
smaller	O
connectors	O
due	O
to	O
the	O
reduced	O
number	O
of	O
signals	O
required	O
.	O
</s>
<s>
Additionally	O
,	O
there	O
is	O
the	O
iSCSI	B-Protocol
transport	O
,	O
which	O
is	O
not	O
present	O
on	O
the	O
drives	O
themselves	O
,	O
but	O
is	O
used	O
to	O
connect	O
devices	O
using	O
TCP/IP	B-Protocol
networks	I-Protocol
.	O
</s>
<s>
This	O
is	O
"	O
form	O
factor	O
compatible	O
"	O
with	O
the	O
connector	O
on	O
SATA	O
disk	O
drives	O
,	O
meaning	O
that	O
a	O
SATA	O
drive	O
may	O
be	O
installed	O
in	O
an	O
SAS	O
drive	B-Device
bay	I-Device
,	O
and	O
the	O
enclosure	O
can	O
use	O
the	O
Serial	O
ATA	B-Protocol
Tunneling	O
Protocol	O
(	O
STP	O
)	O
to	O
make	O
use	O
of	O
the	O
drive	O
.	O
</s>
<s>
There	O
are	O
keyed	O
parts	O
to	O
the	O
connector	O
on	O
an	O
SAS	O
drive	O
that	O
will	O
prevent	O
it	O
from	O
being	O
inserted	O
into	O
a	O
SATA	O
drive	B-Device
bay	I-Device
.	O
</s>
<s>
More	O
recent	O
FC-AL	O
cables	O
use	O
HSSDC	B-Architecture
connectors	I-Architecture
(	O
electrical	O
)	O
or	O
LC	O
connectors	O
(	O
optical	O
)	O
.	O
</s>
<s>
Many	O
FC-AL	O
products	O
now	O
use	O
an	O
intermediate	O
device	O
called	O
a	O
GBIC	B-Protocol
(	O
GigaBit	B-Protocol
Interface	I-Protocol
Converter	I-Protocol
)	O
which	O
allows	O
more	O
flexibility	O
.	O
</s>
<s>
GBICs	B-Protocol
can	O
interconnect	B-General_Concept
with	O
a	O
range	O
of	O
SFP	B-Protocol
(	O
Small	B-Protocol
Form-factor	I-Protocol
Pluggable	I-Protocol
)	O
connectors	O
.	O
</s>
<s>
iSCSI	B-Protocol
may	O
be	O
interconnected	O
by	O
any	O
means	O
used	O
to	O
build	O
a	O
TCP/IP	B-Protocol
network	I-Protocol
,	O
since	O
the	O
SCSI	B-Architecture
commands	O
are	O
simply	O
being	O
carried	O
over	O
TCP/IP	B-Protocol
.	O
</s>
<s>
Ethernet	B-Protocol
is	O
the	O
predominantly	O
used	O
physical	O
layer	O
.	O
</s>
<s>
The	O
situation	O
is	O
fundamentally	O
similar	O
to	O
that	O
of	O
Parallel	O
SCSI	B-Architecture
drive	O
caddies	O
;	O
there	O
have	O
been	O
a	O
range	O
of	O
manufacturers	O
,	O
and	O
the	O
caddies	O
themselves	O
contain	O
a	O
generic	O
device	O
(	O
with	O
one	O
of	O
the	O
standard	O
internal	O
connectors	O
)	O
which	O
can	O
be	O
removed	O
and	O
replaced	O
.	O
</s>
