<s>
Solid-state	B-Device
storage	I-Device
(	O
SSS	O
)	O
is	O
a	O
type	O
of	O
non-volatile	B-General_Concept
computer	I-General_Concept
storage	I-General_Concept
that	O
stores	O
and	O
retrieves	O
digital	B-General_Concept
information	I-General_Concept
using	O
only	O
electronic	O
circuits	O
,	O
without	O
any	O
involvement	O
of	O
moving	O
mechanical	O
parts	O
.	O
</s>
<s>
Solid-state	B-Device
storage	I-Device
devices	I-Device
typically	O
store	O
data	O
using	O
electrically-programmable	O
non-volatile	B-General_Concept
flash	B-Device
memory	I-Device
,	O
however	O
some	O
devices	O
use	O
battery-backed	O
volatile	B-General_Concept
random-access	B-Architecture
memory	I-Architecture
(	O
RAM	B-Architecture
)	O
.	O
</s>
<s>
Having	O
no	O
moving	O
mechanical	O
parts	O
,	O
solid-state	B-Device
storage	I-Device
is	O
much	O
faster	O
than	O
traditional	O
electromechanical	O
storage	O
;	O
as	O
a	O
downside	O
,	O
solid-state	B-Device
storage	I-Device
is	O
significantly	O
more	O
expensive	O
and	O
suffers	O
from	O
the	O
write	B-Error_Name
amplification	I-Error_Name
phenomenon	O
.	O
</s>
<s>
Solid-state	B-Device
storage	I-Device
devices	I-Device
come	O
in	O
various	O
types	O
,	O
form	O
factors	O
,	O
sizes	O
of	O
storage	O
space	O
,	O
and	O
interfacing	B-Application
options	O
to	O
satisfy	O
application	O
requirements	O
for	O
many	O
different	O
types	O
of	O
computer	O
systems	O
and	O
appliances	O
.	O
</s>
<s>
Historically	O
,	O
secondary	O
storage	O
in	O
computer	O
systems	O
has	O
been	O
implemented	O
primarily	O
by	O
using	O
magnetic	O
properties	O
of	O
the	O
surface	O
coatings	O
applied	O
to	O
rotating	O
platters	B-Device
(	O
in	O
hard	B-Device
disk	I-Device
drives	I-Device
and	O
floppy	B-Device
disks	I-Device
)	O
or	O
linearly	O
moving	O
narrow	O
strips	O
of	O
plastic	O
film	O
(	O
in	O
tape	O
drives	O
)	O
.	O
</s>
<s>
Pairing	O
such	O
magnetic	B-Architecture
media	I-Architecture
with	O
read/write	B-Device
heads	I-Device
allows	O
data	O
to	O
be	O
written	O
by	O
separately	O
magnetizing	O
small	O
sections	O
of	O
the	O
ferromagnetic	O
coating	O
,	O
and	O
read	O
later	O
by	O
detecting	O
the	O
transitions	O
in	O
magnetization	O
.	O
</s>
<s>
For	O
the	O
data	O
to	O
be	O
read	O
or	O
written	O
,	O
exact	O
sections	O
of	O
the	O
magnetic	B-Architecture
media	I-Architecture
need	O
to	O
pass	O
under	O
the	O
read/write	B-Device
heads	I-Device
that	O
flow	O
closely	O
to	O
the	O
media	O
surface	O
;	O
as	O
a	O
result	O
,	O
reading	O
or	O
writing	O
data	O
imposes	O
delays	O
required	O
for	O
the	O
positioning	O
of	O
magnetic	B-Architecture
media	I-Architecture
and	O
heads	O
,	O
with	O
the	O
delays	O
differing	O
depending	O
on	O
the	O
actual	O
technology	O
.	O
</s>
<s>
Over	O
time	O
,	O
the	O
performance	O
gap	O
between	O
the	O
central	B-General_Concept
processing	I-General_Concept
units	I-General_Concept
(	O
CPUs	O
)	O
and	O
electromechanical	O
storage	O
(	O
hard	B-Device
disk	I-Device
drives	I-Device
and	O
their	O
RAID	B-Architecture
setups	O
)	O
widened	O
,	O
requiring	O
advancements	O
in	O
the	O
secondary	O
storage	O
technology	O
.	O
</s>
<s>
A	O
solution	O
was	O
found	O
in	O
flash	B-Device
memory	I-Device
,	O
which	O
is	O
an	O
electronic	O
non-volatile	B-General_Concept
computer	I-General_Concept
storage	I-General_Concept
medium	O
that	O
can	O
be	O
electrically	O
erased	O
and	O
reprogrammed	O
.	O
</s>
<s>
Solid-state	B-Device
storage	I-Device
typically	O
uses	O
the	O
NAND	O
type	O
of	O
flash	B-Device
memory	I-Device
,	O
which	O
may	O
be	O
written	O
and	O
read	O
in	O
chunks	O
much	O
smaller	O
than	O
the	O
entire	O
size	O
of	O
the	O
storage	O
device	O
.	O
</s>
<s>
The	O
size	O
of	O
a	O
minimal	O
chunk	O
(	O
page	O
)	O
for	O
read	O
operations	O
is	O
much	O
smaller	O
than	O
the	O
minimal	O
chunk	O
size	O
(	O
block	O
)	O
for	O
write/erase	O
operations	O
,	O
resulting	O
in	O
an	O
undesirable	O
phenomenon	O
called	O
write	B-Error_Name
amplification	I-Error_Name
that	O
limits	O
the	O
random	O
write	O
performance	O
and	O
write	O
endurance	O
of	O
flash-based	O
solid-state	B-Device
storage	I-Device
devices	I-Device
.	O
</s>
<s>
Another	O
type	O
of	O
solid-state	B-Device
storage	I-Device
devices	I-Device
uses	O
volatile	B-General_Concept
random-access	B-Architecture
memory	I-Architecture
(	O
RAM	B-Architecture
)	O
combined	O
with	O
a	O
battery	O
that	O
allows	O
the	O
contents	O
of	O
RAM	B-Architecture
to	O
be	O
preserved	O
for	O
a	O
limited	O
amount	O
of	O
time	O
after	O
the	O
device	O
's	O
power	O
supply	O
is	O
interrupted	O
.	O
</s>
<s>
As	O
an	O
advantage	O
,	O
RAM-based	O
solid-state	B-Device
storage	I-Device
is	O
much	O
faster	O
compared	O
to	O
flash	O
,	O
and	O
does	O
not	O
experience	O
write	B-Error_Name
amplification	I-Error_Name
.	O
</s>
<s>
As	O
a	O
result	O
of	O
having	O
no	O
moving	O
mechanical	O
parts	O
,	O
solid-state	B-Device
storage	I-Device
virtually	O
eliminates	O
the	O
data	O
access	O
latencies	O
present	O
in	O
electromechanical	O
storage	O
devices	O
,	O
and	O
allows	O
significantly	O
higher	O
rates	O
of	O
I/O	B-General_Concept
operations	I-General_Concept
per	O
second	O
(	O
IOPS	O
)	O
.	O
</s>
<s>
Additionally	O
,	O
solid-state	B-Device
storage	I-Device
allows	O
much	O
faster	O
sequential	B-General_Concept
access	I-General_Concept
to	O
stored	O
data	O
,	O
consumes	O
less	O
power	O
,	O
has	O
better	O
physical	O
shock	O
resistance	O
,	O
and	O
produces	O
less	O
heat	O
and	O
no	O
vibrations	O
during	O
operation	O
.	O
</s>
<s>
As	O
a	O
downside	O
,	O
solid-state	B-Device
storage	I-Device
devices	I-Device
have	O
much	O
higher	O
per-megabyte	O
prices	O
than	O
electromechanical	O
storage	O
devices	O
,	O
and	O
generally	O
come	O
in	O
significantly	O
smaller	O
per-device	O
capacities	O
.	O
</s>
<s>
Moreover	O
,	O
flash-based	O
devices	O
experience	O
the	O
memory	O
wear	O
that	O
reduces	O
their	O
service	O
life	O
by	O
imposing	O
a	O
limited	O
amount	O
of	O
data	O
that	O
may	O
be	O
written	O
to	O
them	O
,	O
resulting	O
from	O
the	O
limitations	O
of	O
flash	B-Device
memory	I-Device
that	O
impose	O
a	O
finite	O
number	O
of	O
program	O
–	O
erase	O
cycles	O
used	O
to	O
write	O
data	O
.	O
</s>
<s>
As	O
a	O
result	O
,	O
solid-state	B-Device
storage	I-Device
is	O
frequently	O
used	O
for	O
the	O
creation	O
of	O
hybrid	B-Device
drives	I-Device
,	O
in	O
which	O
solid-state	B-Device
storage	I-Device
serves	O
as	O
a	O
cache	B-General_Concept
for	O
frequently	O
accessed	O
data	O
instead	O
of	O
being	O
a	O
complete	O
substitute	O
for	O
the	O
traditional	O
secondary	O
storage	O
.	O
</s>
<s>
Solid-state	B-Device
storage	I-Device
devices	I-Device
serve	O
as	O
secondary	O
storage	O
components	O
for	O
more	O
complex	O
systems	O
,	O
which	O
may	O
range	O
from	O
embedded	B-Architecture
and	O
portable	B-Application
devices	I-Application
to	O
large	O
servers	B-Application
and	O
dedicated	O
network-attached	B-Application
storage	I-Application
(	O
NAS	B-Application
)	O
systems	O
.	O
</s>
<s>
As	O
a	O
result	O
,	O
solid-state	B-Device
storage	I-Device
devices	I-Device
exist	O
in	O
different	O
capacities	O
,	O
physical	O
layouts	O
and	O
dimensions	O
,	O
using	O
various	O
interfaces	B-Application
and	O
providing	O
different	O
feature	O
sets	O
.	O
</s>
<s>
Less	O
complex	O
solid-state	B-Device
storage	I-Device
devices	I-Device
such	O
as	O
memory	B-Device
cards	I-Device
use	O
simpler	O
,	O
slower	O
interfaces	B-Application
such	O
as	O
the	O
one-bit	O
SD	O
interface	O
or	O
SPI	B-Architecture
,	O
while	O
more	O
sophisticated	O
high-performance	O
devices	O
use	O
faster	O
interfaces	B-Application
such	O
as	O
Serial	O
ATA	O
(	O
SATA	O
)	O
or	O
PCI	O
Express	O
(	O
PCIe	O
)	O
paired	O
with	O
logical	O
device	O
interfaces	B-Application
such	O
as	O
AHCI	O
or	O
NVM	B-Application
Express	I-Application
(	O
NVMe	B-Application
)	O
.	O
</s>
<s>
Types	O
of	O
flash-based	O
solid-state	B-Device
storage	I-Device
devices	I-Device
include	O
the	O
following	O
:	O
</s>
