<s>
A	O
blade	B-Architecture
server	I-Architecture
is	O
a	O
stripped-down	O
server	B-Application
computer	I-Application
with	O
a	O
modular	O
design	O
optimized	O
to	O
minimize	O
the	O
use	O
of	O
physical	O
space	O
and	O
energy	O
.	O
</s>
<s>
Blade	B-Architecture
servers	I-Architecture
have	O
many	O
components	O
removed	O
to	O
save	O
space	O
,	O
minimize	O
power	O
consumption	O
and	O
other	O
considerations	O
,	O
while	O
still	O
having	O
all	O
the	O
functional	O
components	O
to	O
be	O
considered	O
a	O
computer	O
.	O
</s>
<s>
Unlike	O
a	O
rack-mount	B-Application
server	O
,	O
a	O
blade	B-Architecture
server	I-Architecture
fits	O
inside	O
a	O
blade	B-Architecture
enclosure	I-Architecture
,	O
which	O
can	O
hold	O
multiple	O
blade	B-Architecture
servers	I-Architecture
,	O
providing	O
services	O
such	O
as	O
power	O
,	O
cooling	O
,	O
networking	O
,	O
various	O
interconnects	O
and	O
management	O
.	O
</s>
<s>
Together	O
,	O
blades	O
and	O
the	O
blade	B-Architecture
enclosure	I-Architecture
form	O
a	O
blade	B-Architecture
system	I-Architecture
,	O
which	O
may	O
itself	O
be	O
rack-mounted	B-Application
.	O
</s>
<s>
Different	O
blade	O
providers	O
have	O
differing	O
principles	O
regarding	O
what	O
to	O
include	O
in	O
the	O
blade	O
itself	O
,	O
and	O
in	O
the	O
blade	B-Architecture
system	I-Architecture
as	O
a	O
whole	O
.	O
</s>
<s>
The	O
most	O
common	O
computer	B-Application
rack	I-Application
form-factor	O
is	O
42U	O
high	O
,	O
which	O
limits	O
the	O
number	O
of	O
discrete	O
computer	O
devices	O
directly	O
mountable	O
in	O
a	O
rack	O
to	O
42	O
components	O
.	O
</s>
<s>
,	O
densities	O
of	O
up	O
to	O
180	O
servers	O
per	O
blade	B-Architecture
system	I-Architecture
(	O
or	O
1440	O
servers	O
per	O
rack	O
)	O
are	O
achievable	O
with	O
blade	B-Architecture
systems	I-Architecture
.	O
</s>
<s>
By	O
locating	O
these	O
services	O
in	O
one	O
place	O
and	O
sharing	O
them	O
among	O
the	O
blade	B-Architecture
computers	I-Architecture
,	O
the	O
overall	O
utilization	O
becomes	O
higher	O
.	O
</s>
<s>
The	O
blade	B-Architecture
enclosure	I-Architecture
's	O
power	O
supply	O
provides	O
a	O
single	O
power	O
source	O
for	O
all	O
blades	O
within	O
the	O
enclosure	O
.	O
</s>
<s>
The	O
popularity	O
of	O
blade	B-Architecture
servers	I-Architecture
,	O
and	O
their	O
own	O
appetite	O
for	O
power	O
,	O
has	O
led	O
to	O
an	O
increase	O
in	O
the	O
number	O
of	O
rack-mountable	B-Application
uninterruptible	O
power	O
supply	O
(	O
or	O
UPS	O
)	O
units	O
,	O
including	O
units	O
targeted	O
specifically	O
towards	O
blade	B-Architecture
servers	I-Architecture
(	O
such	O
as	O
the	O
BladeUPS	B-Device
)	O
.	O
</s>
<s>
Most	O
blade	B-Architecture
enclosures	I-Architecture
,	O
like	O
most	O
computing	O
systems	O
,	O
remove	O
heat	O
by	O
using	O
fans	O
.	O
</s>
<s>
At	O
the	O
same	O
time	O
,	O
the	O
increased	O
density	O
of	O
blade-server	O
configurations	O
can	O
still	O
result	O
in	O
higher	O
overall	O
demands	O
for	O
cooling	O
with	O
racks	B-Application
populated	O
at	O
over	O
50%	O
full	O
.	O
</s>
<s>
In	O
absolute	O
terms	O
,	O
a	O
fully	O
populated	O
rack	O
of	O
blade	B-Architecture
servers	I-Architecture
is	O
likely	O
to	O
require	O
more	O
cooling	O
capacity	O
than	O
a	O
fully	O
populated	O
rack	O
of	O
standard	O
1U	O
servers	O
.	O
</s>
<s>
This	O
is	O
because	O
one	O
can	O
fit	O
up	O
to	O
128	O
blade	B-Architecture
servers	I-Architecture
in	O
the	O
same	O
rack	O
that	O
will	O
only	O
hold	O
42	O
1U	O
rack-mount	B-Application
servers	O
.	O
</s>
<s>
Blade	B-Architecture
servers	I-Architecture
generally	O
include	O
integrated	O
or	O
optional	O
network	B-Protocol
interface	I-Protocol
controllers	I-Protocol
for	O
Ethernet	O
or	O
host	B-Architecture
adapters	I-Architecture
for	O
Fibre	B-Architecture
Channel	I-Architecture
storage	O
systems	O
or	O
converged	B-Protocol
network	I-Protocol
adapter	I-Protocol
to	O
combine	O
storage	O
and	O
data	O
via	O
one	O
Fibre	B-Protocol
Channel	I-Protocol
over	I-Protocol
Ethernet	I-Protocol
interface	O
.	O
</s>
<s>
In	O
many	O
blades	O
,	O
at	O
least	O
one	O
interface	O
is	O
embedded	O
on	O
the	O
motherboard	O
and	O
extra	O
interfaces	O
can	O
be	O
added	O
using	O
mezzanine	B-Device
cards	I-Device
.	O
</s>
<s>
A	O
blade	B-Architecture
enclosure	I-Architecture
can	O
provide	O
individual	O
external	O
ports	O
to	O
which	O
each	O
network	O
interface	O
on	O
a	O
blade	O
will	O
connect	O
.	O
</s>
<s>
Alternatively	O
,	O
a	O
blade	B-Architecture
enclosure	I-Architecture
can	O
aggregate	O
network	O
interfaces	O
into	O
interconnect	O
devices	O
(	O
such	O
as	O
switches	O
)	O
built	O
into	O
the	O
blade	B-Architecture
enclosure	I-Architecture
or	O
in	O
networking	O
blades	O
.	O
</s>
<s>
While	O
computers	O
typically	O
use	O
hard	B-Device
disks	I-Device
to	O
store	O
operating	O
systems	O
,	O
applications	O
and	O
data	O
,	O
these	O
are	O
not	O
necessarily	O
required	O
locally	O
.	O
</s>
<s>
FireWire	B-Protocol
,	O
SATA	O
,	O
E-SATA	O
,	O
SCSI	B-Architecture
,	O
SAS	O
DAS	B-General_Concept
,	O
FC	B-Architecture
and	O
iSCSI	B-Protocol
)	O
are	O
readily	O
moved	O
outside	O
the	O
server	O
,	O
though	O
not	O
all	O
are	O
used	O
in	O
enterprise-level	O
installations	O
.	O
</s>
<s>
Implementing	O
these	O
connection	O
interfaces	O
within	O
the	O
computer	O
presents	O
similar	O
challenges	O
to	O
the	O
networking	O
interfaces	O
(	O
indeed	O
iSCSI	B-Protocol
runs	O
over	O
the	O
network	O
interface	O
)	O
,	O
and	O
similarly	O
these	O
can	O
be	O
removed	O
from	O
the	O
blade	O
and	O
presented	O
individually	O
or	O
aggregated	O
either	O
on	O
the	O
chassis	O
or	O
through	O
other	O
blades	O
.	O
</s>
<s>
The	O
ability	O
to	O
boot	O
the	O
blade	O
from	O
a	O
storage	O
area	O
network	O
(	O
SAN	O
)	O
allows	O
for	O
an	O
entirely	O
disk-free	O
blade	O
,	O
an	O
example	O
of	O
which	O
implementation	O
is	O
the	O
Intel	B-Application
Modular	I-Application
Server	I-Application
System	I-Application
.	O
</s>
<s>
Since	O
blade	B-Architecture
enclosures	I-Architecture
provide	O
a	O
standard	O
method	O
for	O
delivering	O
basic	O
services	O
to	O
computer	O
devices	O
,	O
other	O
types	O
of	O
devices	O
can	O
also	O
utilize	O
blade	B-Architecture
enclosures	I-Architecture
.	O
</s>
<s>
Blade	B-Architecture
servers	I-Architecture
function	O
well	O
for	O
specific	O
purposes	O
such	O
as	O
web	O
hosting	O
,	O
virtualization	B-General_Concept
,	O
and	O
cluster	B-Architecture
computing	I-Architecture
.	O
</s>
<s>
Individual	O
blades	O
are	O
typically	O
hot-swappable	B-Device
.	O
</s>
<s>
As	O
users	O
deal	O
with	O
larger	O
and	O
more	O
diverse	O
workloads	O
,	O
they	O
add	O
more	O
processing	O
power	O
,	O
memory	O
and	O
I/O	O
bandwidth	O
to	O
blade	B-Architecture
servers	I-Architecture
.	O
</s>
<s>
Although	O
blade-server	O
technology	O
in	O
theory	O
allows	O
for	O
open	O
,	O
cross-vendor	O
systems	O
,	O
most	O
users	O
buy	O
modules	O
,	O
enclosures	O
,	O
racks	B-Application
and	O
management	O
tools	O
from	O
the	O
same	O
vendor	O
.	O
</s>
<s>
Blade	B-Architecture
servers	I-Architecture
do	O
not	O
,	O
however	O
,	O
provide	O
the	O
answer	O
to	O
every	O
computing	O
problem	O
.	O
</s>
<s>
One	O
can	O
view	O
them	O
as	O
a	O
form	O
of	O
productized	O
server-farm	B-Operating_System
that	O
borrows	O
from	O
mainframe	B-Architecture
packaging	O
,	O
cooling	O
,	O
and	O
power-supply	O
technology	O
.	O
</s>
<s>
Very	O
large	O
computing	O
tasks	O
may	O
still	O
require	O
server	B-Operating_System
farms	I-Operating_System
of	O
blade	B-Architecture
servers	I-Architecture
,	O
and	O
because	O
of	O
blade	B-Architecture
servers	I-Architecture
 '	O
high	O
power	O
density	O
,	O
can	O
suffer	O
even	O
more	O
acutely	O
from	O
the	O
heating	O
,	O
ventilation	O
,	O
and	O
air	O
conditioning	O
problems	O
that	O
affect	O
large	O
conventional	O
server	B-Operating_System
farms	I-Operating_System
.	O
</s>
<s>
Developers	O
first	O
placed	O
complete	O
microcomputers	B-Architecture
on	O
cards	O
and	O
packaged	O
them	O
in	O
standard	O
19-inch	B-Application
racks	I-Application
in	O
the	O
1970s	O
,	O
soon	O
after	O
the	O
introduction	O
of	O
8-bit	O
microprocessors	B-Architecture
.	O
</s>
<s>
This	O
architecture	O
was	O
used	O
in	O
the	O
industrial	O
process	O
control	O
industry	O
as	O
an	O
alternative	O
to	O
minicomputer-based	O
control	O
systems	O
.	O
</s>
<s>
Early	O
models	O
stored	O
programs	O
in	O
EPROM	B-General_Concept
and	O
were	O
limited	O
to	O
a	O
single	O
function	O
with	O
a	O
small	O
real-time	B-Operating_System
executive	I-Operating_System
.	O
</s>
<s>
The	O
VMEbus	B-Architecture
architecture	O
(	O
)	O
defined	O
a	O
computer	O
interface	O
that	O
included	O
implementation	O
of	O
a	O
board-level	O
computer	O
installed	O
in	O
a	O
chassis	O
backplane	O
with	O
multiple	O
slots	O
for	O
pluggable	O
boards	O
to	O
provide	O
I/O	O
,	O
memory	O
,	O
or	O
additional	O
computing	O
.	O
</s>
<s>
In	O
the	O
1990s	O
,	O
the	O
PCI	B-Protocol
Industrial	O
Computer	O
Manufacturers	O
Group	O
PICMG	O
developed	O
a	O
chassis/blade	O
structure	O
for	O
the	O
then	O
emerging	O
Peripheral	B-Protocol
Component	I-Protocol
Interconnect	I-Protocol
bus	O
PCI	B-Protocol
called	O
CompactPCI	O
.	O
</s>
<s>
Moreover	O
this	O
system	O
architecture	O
provided	O
management	O
capabilities	O
not	O
present	O
in	O
typical	O
rack	B-Application
mount	I-Application
computers	O
,	O
much	O
more	O
like	O
in	O
ultra-high	O
reliability	O
systems	O
,	O
managing	O
power	O
supplies	O
,	O
cooling	O
fans	O
as	O
well	O
as	O
monitoring	O
health	O
of	O
other	O
internal	O
components	O
.	O
</s>
<s>
In	O
1998	O
and	O
1999	O
this	O
new	O
Blade	B-Architecture
Server	I-Architecture
Architecture	O
was	O
developed	O
at	O
Ziatech	O
based	O
on	O
their	O
Compact	O
PCI	B-Protocol
platform	O
to	O
house	O
as	O
many	O
as	O
14	O
"	O
blade	B-Architecture
servers	I-Architecture
"	O
in	O
a	O
standard	O
19	B-Application
"	I-Application
9U	O
high	O
rack	B-Application
mounted	I-Application
chassis	O
,	O
allowing	O
in	O
this	O
configuration	O
as	O
many	O
as	O
84	O
servers	O
in	O
a	O
standard	O
84	O
Rack	O
Unit	O
19	B-Application
"	I-Application
rack	I-Application
.	O
</s>
<s>
The	O
ability	O
to	O
change/replace	O
or	O
add	O
modules	O
within	O
the	O
system	O
while	O
it	O
is	O
in	O
operation	O
is	O
known	O
as	O
Hot-Swap	B-Device
.	O
</s>
<s>
Unique	O
to	O
any	O
other	O
server	O
system	O
the	O
Ketris	O
Blade	B-Architecture
servers	I-Architecture
routed	O
Ethernet	O
across	O
the	O
backplane	O
(	O
where	O
server	B-Architecture
blades	I-Architecture
would	O
plug-in	O
)	O
eliminating	O
more	O
than	O
160	O
cables	O
in	O
a	O
single	O
84	O
Rack	O
Unit	O
high	O
19	B-Application
"	I-Application
rack	I-Application
.	O
</s>
<s>
Further	O
this	O
architecture	O
provided	O
the	O
capabilities	O
to	O
inventory	O
modules	O
installed	O
in	O
the	O
system	O
remotely	O
in	O
each	O
system	O
chassis	O
without	O
the	O
blade	B-Architecture
servers	I-Architecture
operating	O
.	O
</s>
<s>
The	O
system	O
architecture	O
when	O
this	O
system	O
was	O
announced	O
was	O
called	O
Ketris	O
,	O
named	O
after	O
the	O
Ketri	B-Application
Sword	I-Application
,	O
worn	O
by	O
nomads	O
in	O
such	O
a	O
way	O
as	O
to	O
be	O
drawn	O
very	O
quickly	O
as	O
needed	O
.	O
</s>
<s>
Patents	O
were	O
awarded	O
for	O
the	O
Ketris	O
blade	B-Architecture
server	I-Architecture
architecture	O
.	O
</s>
<s>
In	O
October	O
2000	O
Ziatech	O
was	O
acquired	O
by	O
Intel	O
Corp	O
and	O
the	O
Ketris	O
Blade	B-Architecture
Server	I-Architecture
systems	O
would	O
become	O
a	O
product	O
of	O
the	O
Intel	O
Network	O
Products	O
Group	O
.	O
</s>
<s>
This	O
provided	O
the	O
first	O
open	B-Architecture
architecture	I-Architecture
for	O
a	O
multi-server	O
chassis	O
.	O
</s>
<s>
While	O
AdvancedTCA	O
system	O
and	O
boards	O
typically	O
sell	O
for	O
higher	O
prices	O
than	O
blade	B-Architecture
servers	I-Architecture
,	O
the	O
operating	O
cost	O
(	O
manpower	O
to	O
manage	O
and	O
maintain	O
)	O
are	O
dramatically	O
lower	O
,	O
where	O
operating	O
cost	O
often	O
dwarf	O
the	O
acquisition	O
cost	O
for	O
traditional	O
servers	O
.	O
</s>
<s>
AdvancedTCA	O
promote	O
them	O
for	O
telecommunications	O
customers	O
,	O
however	O
in	O
the	O
real	O
world	O
implementation	O
in	O
Internet	O
Data	O
Centers	O
where	O
thermal	O
as	O
well	O
as	O
other	O
maintenance	O
and	O
operating	O
cost	O
had	O
become	O
prohibitively	O
expensive	O
,	O
this	O
blade	B-Architecture
server	I-Architecture
architecture	O
with	O
remote	O
automated	O
provisioning	O
,	O
health	O
and	O
performance	O
monitoring	O
and	O
management	O
would	O
be	O
a	O
significantly	O
less	O
expensive	O
operating	O
cost	O
.	O
</s>
<s>
RLX	O
,	O
which	O
consisted	O
primarily	O
of	O
former	O
Compaq	O
Computer	O
Corporation	O
employees	O
,	O
including	O
Hipp	O
and	O
Kirkeby	O
,	O
shipped	O
its	O
first	O
commercial	O
blade	B-Architecture
server	I-Architecture
in	O
2001	O
.	O
</s>
<s>
The	O
name	O
blade	B-Architecture
server	I-Architecture
appeared	O
when	O
a	O
card	O
included	O
the	O
processor	O
,	O
memory	O
,	O
I/O	O
and	O
non-volatile	O
program	O
storage	O
(	O
flash	B-Device
memory	I-Device
or	O
small	O
hard	O
disk(s )	O
)	O
.	O
</s>
<s>
Other	O
companies	O
selling	O
blade	B-Architecture
servers	I-Architecture
include	O
Supermicro	O
,	O
Hitachi	O
.	O
</s>
<s>
The	O
prominent	O
brands	O
in	O
the	O
blade	B-Architecture
server	I-Architecture
market	O
are	O
Supermicro	O
,	O
Cisco	O
Systems	O
,	O
HPE	O
,	O
Dell	O
and	O
IBM	O
,	O
though	O
the	O
latter	O
sold	O
its	O
x86	B-Operating_System
server	O
business	O
to	O
Lenovo	O
in	O
2014	O
after	O
selling	O
its	O
consumer	O
PC	O
line	O
to	O
Lenovo	O
in	O
2005	O
.	O
</s>
<s>
In	O
2009	O
,	O
Cisco	O
announced	O
blades	O
in	O
its	O
Unified	B-Application
Computing	I-Application
System	I-Application
product	O
line	O
,	O
consisting	O
of	O
6U	O
high	O
chassis	O
,	O
up	O
to	O
8	O
blade	B-Architecture
servers	I-Architecture
in	O
each	O
chassis	O
.	O
</s>
<s>
It	O
had	O
a	O
heavily	O
modified	O
Nexus	O
5K	O
switch	O
,	O
rebranded	O
as	O
a	O
fabric	B-General_Concept
interconnect	O
,	O
and	O
management	O
software	O
for	O
the	O
whole	O
system	O
.	O
</s>
<s>
HP	O
's	O
initial	O
line	O
consisted	O
of	O
two	O
chassis	O
models	O
,	O
the	O
c3000	O
which	O
holds	O
up	O
to	O
8	O
half-height	O
ProLiant	B-Device
line	O
blades	O
(	O
also	O
available	O
in	O
tower	O
form	O
)	O
,	O
and	O
the	O
c7000	O
(	O
10U	O
)	O
which	O
holds	O
up	O
to	O
16	O
half-height	O
ProLiant	B-Device
blades	O
.	O
</s>
<s>
Dell	O
's	O
product	O
,	O
the	O
M1000e	B-Application
is	O
a	O
10U	O
modular	O
enclosure	O
and	O
holds	O
up	O
to	O
16	O
half-height	O
PowerEdge	B-Device
blade	B-Architecture
servers	I-Architecture
or	O
32	O
quarter-height	O
blades	O
.	O
</s>
