<s>
Magnetic-tape	B-Architecture
data	I-Architecture
storage	I-Architecture
is	O
a	O
system	O
for	O
storing	O
digital	B-General_Concept
information	I-General_Concept
on	O
magnetic	O
tape	O
using	O
digital	O
recording	O
.	O
</s>
<s>
Tape	O
was	O
an	O
important	O
medium	O
for	O
primary	B-General_Concept
data	I-General_Concept
storage	I-General_Concept
in	O
early	O
computers	O
,	O
typically	O
using	O
large	O
open	O
reels	O
of	O
7-track	B-Device
,	O
later	O
9-track	B-Device
tape	I-Device
.	O
</s>
<s>
Modern	O
magnetic	O
tape	O
is	O
most	O
commonly	O
packaged	O
in	O
cartridges	O
and	O
cassettes	O
,	O
such	O
as	O
the	O
widely	O
supported	O
Linear	B-Operating_System
Tape-Open	I-Operating_System
(	O
LTO	O
)	O
and	O
IBM	O
3592	B-Device
series	O
.	O
</s>
<s>
Autoloaders	O
and	O
tape	B-Device
libraries	I-Device
are	O
often	O
used	O
to	O
automate	O
cartridge	O
handling	O
and	O
exchange	O
.	O
</s>
<s>
Tape	B-Architecture
data	I-Architecture
storage	I-Architecture
is	O
now	O
used	O
more	O
for	O
system	O
backup	B-Protocol
,	O
data	O
archive	O
and	O
data	O
exchange	O
.	O
</s>
<s>
With	O
the	O
introduction	O
of	O
the	O
IBM	B-Device
3480	I-Device
cartridge	I-Device
in	O
1984	O
,	O
described	O
as	O
"	O
about	O
one-fourth	O
the	O
size	O
...	O
yet	O
it	O
stored	O
up	O
to	O
20	O
percent	O
more	O
data	O
"	O
,	O
large	O
computer	O
systems	O
started	O
to	O
move	O
away	O
from	O
open-reel	O
tapes	O
and	O
towards	O
cartridges	O
.	O
</s>
<s>
The	O
UNISERVO	B-Device
drive	O
recording	O
medium	O
was	O
a	O
thin	O
metal	O
strip	O
of	O
wide	O
nickel-plated	O
phosphor	O
bronze	O
.	O
</s>
<s>
Of	O
the	O
eight	O
tracks	O
,	O
six	O
were	O
data	O
,	O
one	O
was	O
for	O
parity	B-Error_Name
,	O
and	O
one	O
was	O
a	O
clock	O
,	O
or	O
timing	O
track	O
.	O
</s>
<s>
IBM	B-Device
computers	I-Device
from	I-Device
the	I-Device
1950s	I-Device
used	O
ferric-oxide-coated	O
tape	O
similar	O
to	O
that	O
used	O
in	O
audio	O
recording	O
.	O
</s>
<s>
CDC	O
used	O
IBM-compatible	O
magnetic	O
tapes	O
,	O
but	O
also	O
offered	O
a	O
variant	O
,	O
with	O
14	O
tracks	O
(	O
12	O
data	O
tracks	O
corresponding	O
to	O
the	O
12-bit	O
word	O
of	O
CDC	B-Device
6000	I-Device
series	I-Device
peripheral	O
processors	O
,	O
plus	O
2	O
parity	B-Error_Name
bits	I-Error_Name
)	O
in	O
the	O
CDC626	O
drive	O
.	O
</s>
<s>
Early	O
IBM	O
tape	O
drives	O
,	O
such	O
as	O
the	O
IBM	O
727	O
and	O
IBM	O
729	O
,	O
were	O
mechanically	O
sophisticated	O
floor-standing	O
drives	O
that	O
used	O
vacuum	B-Device
columns	I-Device
to	O
buffer	O
long	O
u-shaped	O
loops	O
of	O
tape	O
.	O
</s>
<s>
Between	O
servo	O
control	O
of	O
powerful	O
reel	O
motors	O
,	O
a	O
low-mass	O
capstan	O
drive	O
,	O
and	O
the	O
low-friction	O
and	O
controlled	O
tension	O
of	O
the	O
vacuum	B-Device
columns	I-Device
,	O
fast	O
start	O
and	O
stop	O
of	O
the	O
tape	O
at	O
the	O
tape-to-head	O
interface	O
could	O
be	O
achieved	O
.	O
</s>
<s>
The	O
fast	O
acceleration	O
is	O
possible	O
because	O
the	O
tape	O
mass	O
in	O
the	O
vacuum	B-Device
columns	I-Device
is	O
small	O
;	O
the	O
length	O
of	O
tape	O
buffered	O
in	O
the	O
columns	O
provides	O
time	O
to	O
accelerate	O
the	O
high-inertia	O
reels	O
.	O
</s>
<s>
When	O
active	O
,	O
the	O
two	O
tape	O
reels	O
thus	O
fed	O
tape	O
into	O
or	O
pulled	O
tape	O
out	O
of	O
the	O
vacuum	B-Device
columns	I-Device
,	O
intermittently	O
spinning	O
in	O
rapid	O
,	O
unsynchronized	O
bursts	O
,	O
resulting	O
in	O
visually	O
striking	O
action	O
.	O
</s>
<s>
Early	O
half-inch	O
tape	O
had	O
seven	O
parallel	O
tracks	O
of	O
data	O
along	O
the	O
length	O
of	O
the	O
tape	O
,	O
allowing	O
6-bit	O
characters	O
plus	O
1bit	O
of	O
parity	B-Error_Name
written	O
across	O
the	O
tape	O
.	O
</s>
<s>
This	O
was	O
known	O
as	O
7-track	B-Device
tape	I-Device
.	O
</s>
<s>
With	O
the	O
introduction	O
of	O
the	O
IBM	B-Application
System/360	I-Application
mainframe	O
,	O
9-track	B-Device
tapes	I-Device
were	O
introduced	O
to	O
support	O
the	O
new	O
8-bit	O
characters	O
that	O
it	O
used	O
.	O
</s>
<s>
Common	O
7-track	B-Device
densities	O
started	O
at	O
200	O
characters	O
per	O
inch	O
(	O
CPI	O
)	O
,	O
then	O
556	O
,	O
and	O
finally	O
800	O
;	O
9-track	B-Device
tapes	I-Device
had	O
densities	O
of	O
800	O
(	O
using	O
NRZI	O
)	O
,	O
then	O
1600	O
(	O
using	O
PE	B-Protocol
)	O
,	O
and	O
finally	O
6250	O
(	O
using	O
GCR	B-Device
)	O
.	O
</s>
<s>
Effective	O
density	O
also	O
increased	O
as	O
the	O
interblock	O
gap	O
(	O
inter-record	O
gap	O
)	O
decreased	O
from	O
a	O
nominal	O
on	O
7-track	B-Device
tape	I-Device
reel	O
to	O
a	O
nominal	O
on	O
a	O
6250bpi	O
9-track	B-Device
tape	I-Device
reel	O
.	O
</s>
<s>
At	O
least	O
partly	O
due	O
to	O
the	O
success	O
of	O
the	O
System/360	B-Application
,	O
and	O
the	O
resultant	O
standardization	O
on	O
8-bit	O
character	O
codes	O
and	O
byte	B-Application
addressing	O
,	O
9-track	B-Device
tapes	I-Device
were	O
very	O
widely	O
used	O
throughout	O
the	O
computer	O
industry	O
during	O
the	O
1970s	O
and	O
1980s	O
.	O
</s>
<s>
IBM	O
discontinued	O
new	O
reel-to-reel	O
products	O
replacing	O
them	O
with	O
cartridge	O
based	O
products	O
beginning	O
with	O
its	O
1984	O
introduction	O
of	O
the	O
cartridge-based	O
3480	B-Device
family	O
.	O
</s>
<s>
LINCtapes	O
and	O
DECtapes	O
had	O
similar	O
capacity	O
and	O
data	O
transfer	O
rate	O
to	O
the	O
diskettes	B-Device
that	O
displaced	O
them	O
,	O
but	O
their	O
access	B-General_Concept
times	I-General_Concept
were	O
on	O
the	O
order	O
of	O
thirty	O
seconds	O
to	O
a	O
minute	O
.	O
</s>
<s>
The	O
IBM	B-Device
7340	I-Device
Hypertape	I-Device
drive	O
,	O
introduced	O
in	O
1961	O
,	O
used	O
a	O
dual	O
reel	O
cassette	O
with	O
a	O
tape	O
capable	O
of	O
holding	O
2	O
million	O
six-bit	O
characters	O
per	O
cassette	O
.	O
</s>
<s>
In	O
the	O
1970s	O
and	O
1980s	O
,	O
audio	O
Compact	O
Cassettes	O
were	O
frequently	O
used	O
as	O
an	O
inexpensive	O
data	O
storage	B-General_Concept
system	I-General_Concept
for	O
home	O
computers	O
,	O
or	O
in	O
some	O
cases	O
for	O
diagnostics	O
or	O
boot	O
code	O
for	O
larger	O
systems	O
such	O
as	O
the	O
Burroughs	B-Device
B1700	I-Device
.	O
</s>
<s>
Early	O
cartridges	O
were	O
available	O
before	O
personal	O
computers	O
had	O
affordable	O
disk	O
drives	O
,	O
and	O
could	O
be	O
used	O
as	O
random	B-General_Concept
access	I-General_Concept
devices	O
,	O
automatically	O
winding	O
and	O
positioning	O
the	O
tape	O
,	O
albeit	O
with	O
access	B-General_Concept
times	I-General_Concept
of	O
many	O
seconds	O
.	O
</s>
<s>
In	O
1984	O
IBM	O
introduced	O
the	O
3480	B-Device
family	I-Device
of	O
single	O
reel	O
cartridges	O
and	O
tape	O
drives	O
which	O
were	O
then	O
manufactured	O
by	O
a	O
number	O
of	O
vendors	O
through	O
at	O
least	O
2004	O
.	O
</s>
<s>
DLT	B-Device
(	O
Digital	B-Device
Linear	I-Device
Tape	I-Device
)	O
,	O
also	O
a	O
cartridge-based	O
tape	O
,	O
was	O
available	O
beginning	O
1984	O
but	O
as	O
of	O
2007	O
future	O
development	O
was	O
stopped	O
in	O
favor	O
of	O
LTO	O
.	O
</s>
<s>
In	O
2003	O
IBM	O
introduced	O
the	O
3592	B-Device
family	I-Device
to	O
supersede	O
the	O
IBM	B-Device
3590	I-Device
.	O
</s>
<s>
While	O
the	O
name	O
is	O
similar	O
,	O
there	O
is	O
no	O
compatibility	O
between	O
the	O
3590	O
and	O
the	O
3592	B-Device
.	O
</s>
<s>
Like	O
the	O
3590	O
and	O
3480	B-Device
before	O
it	O
,	O
this	O
tape	O
format	O
has	O
tape	O
spooled	O
into	O
a	O
single	O
reel	O
cartridge	O
.	O
</s>
<s>
Linear	B-Operating_System
Tape-Open	I-Operating_System
(	O
LTO	O
)	O
single-reel	O
cartridge	O
was	O
announced	O
in	O
1997	O
at	O
100	O
megabytes	O
and	O
in	O
its	O
eighth	O
generation	O
supports	O
12	O
terabytes	O
in	O
the	O
same	O
sized	O
cartridge	O
.	O
</s>
<s>
LTO	O
has	O
completely	O
displaced	O
all	O
other	O
tape	O
technologies	O
in	O
computer	O
applications	O
,	O
with	O
the	O
exception	O
of	O
some	O
IBM	B-Device
3592	I-Device
family	I-Device
at	O
the	O
high-end	O
.	O
</s>
<s>
(	O
BPI	O
)	O
is	O
the	O
metric	O
for	O
the	O
density	O
at	O
which	O
data	O
is	O
stored	O
on	O
magnetic	B-Architecture
media	I-Architecture
.	O
</s>
<s>
The	O
term	O
BPI	O
can	O
refer	O
to	O
,	O
but	O
more	O
often	O
refers	O
to	O
bytes	B-Application
per	O
inch	O
.	O
</s>
<s>
The	O
term	O
BPI	O
can	O
mean	O
bytes	B-Application
per	O
inch	O
when	O
the	O
tracks	O
of	O
a	O
particular	O
format	O
are	O
byte-organized	O
,	O
as	O
in	O
9-track	B-Device
tapes	I-Device
.	O
</s>
<s>
It	O
is	O
the	O
simplest	O
recording	O
method	O
,	O
but	O
also	O
has	O
the	O
lowest	O
data	B-Device
density	I-Device
.	O
</s>
<s>
Compared	O
to	O
simple	O
linear	O
recording	O
,	O
using	O
the	O
same	O
tape	O
length	O
and	O
the	O
same	O
number	O
of	O
heads	O
,	O
data	O
storage	B-General_Concept
capacity	I-General_Concept
is	O
substantially	O
higher	O
.	O
</s>
<s>
In	O
the	O
past	O
,	O
the	O
host	O
block	O
size	O
affected	O
the	O
data	B-Device
density	I-Device
on	O
tape	O
,	O
but	O
on	O
modern	O
drives	O
,	O
data	O
is	O
typically	O
organized	O
into	O
fixed-sized	O
blocks	O
which	O
may	O
or	O
may	O
not	O
be	O
compressed	O
or	O
encrypted	O
,	O
and	O
host	O
block	O
size	O
no	O
longer	O
affects	O
data	B-Device
density	I-Device
on	O
tape	O
.	O
</s>
<s>
In	O
the	O
past	O
,	O
the	O
size	O
of	O
the	O
inter-block	O
gap	O
was	O
constant	O
,	O
while	O
the	O
size	O
of	O
the	O
data	O
block	O
was	O
based	O
on	O
host	O
block	O
size	O
,	O
affecting	O
tape	O
capacity	O
–	O
for	O
example	O
,	O
on	O
count	B-Application
key	I-Application
data	I-Application
storage	O
.	O
</s>
<s>
Linear	B-Operating_System
Tape-Open	I-Operating_System
type	O
drives	O
use	O
a	O
fixed-size	O
block	O
for	O
tape	O
(	O
a	O
fixed-block	B-Device
architecture	I-Device
)	O
,	O
independent	O
of	O
the	O
host	O
block	O
size	O
,	O
and	O
the	O
inter-block	O
gap	O
is	O
variable	O
to	O
assist	O
with	O
speed	O
matching	O
during	O
writes	O
.	O
</s>
<s>
Tape	O
is	O
characterized	O
by	O
sequential	B-General_Concept
access	I-General_Concept
to	O
data	O
.	O
</s>
<s>
By	O
contrast	O
,	O
hard	O
disk	O
technology	O
can	O
perform	O
the	O
equivalent	O
action	O
in	O
tens	O
of	O
milliseconds	O
(	O
3	O
orders	O
of	O
magnitude	O
faster	O
)	O
and	O
can	O
be	O
thought	O
of	O
as	O
offering	O
random	B-General_Concept
access	I-General_Concept
to	O
data	O
.	O
</s>
<s>
File	B-Application
systems	I-Application
require	O
data	O
and	O
metadata	O
to	O
be	O
stored	O
on	O
the	O
data	O
storage	O
medium	O
.	O
</s>
<s>
Storing	O
metadata	O
in	O
one	O
place	O
and	O
data	O
in	O
another	O
,	O
as	O
is	O
done	O
with	O
disk-based	O
file	B-Application
systems	I-Application
,	O
requires	O
repositioning	O
activity	O
.	O
</s>
<s>
As	O
a	O
result	O
,	O
most	O
tape	O
systems	O
use	O
a	O
simplified	O
filesystem	B-Application
in	O
which	O
files	O
are	O
addressed	O
by	O
number	O
,	O
not	O
by	O
filename	O
.	O
</s>
<s>
Tape	B-Device
labels	I-Device
store	O
such	O
metadata	O
,	O
and	O
they	O
are	O
used	O
for	O
interchanging	O
data	O
between	O
systems	O
.	O
</s>
<s>
File	B-Application
archiver	I-Application
and	O
backup	B-Protocol
tools	O
have	O
been	O
created	O
to	O
pack	O
multiple	O
files	O
along	O
with	O
the	O
related	O
metadata	O
into	O
a	O
single	O
tape	O
file	O
.	O
</s>
<s>
Serpentine	O
tape	O
drives	O
(	O
e.g.	O
,	O
QIC	B-Device
)	O
offer	O
improved	O
access	B-General_Concept
time	I-General_Concept
by	O
switching	O
to	O
the	O
appropriate	O
track	O
;	O
tape	O
partitions	O
are	O
used	O
for	O
directory	O
information	O
.	O
</s>
<s>
The	O
Linear	B-Device
Tape	I-Device
File	I-Device
System	I-Device
is	O
a	O
method	O
of	O
storing	O
file	O
metadata	O
on	O
a	O
separate	O
part	O
of	O
the	O
tape	O
.	O
</s>
<s>
This	O
makes	O
it	O
possible	O
to	O
copy	B-General_Concept
and	I-General_Concept
paste	I-General_Concept
files	O
or	O
directories	O
to	O
a	O
tape	O
as	O
if	O
it	O
were	O
a	O
disk	O
,	O
but	O
does	O
not	O
change	O
the	O
fundamental	O
sequential	B-General_Concept
access	I-General_Concept
nature	O
of	O
tape	O
.	O
</s>
<s>
Tape	O
has	O
a	O
long	O
random	B-General_Concept
access	I-General_Concept
time	O
since	O
the	O
deck	O
must	O
wind	O
an	O
average	O
of	O
one-third	O
the	O
tape	O
length	O
to	O
move	O
from	O
one	O
arbitrary	O
position	O
to	O
another	O
.	O
</s>
<s>
Most	O
tape	O
drives	O
now	O
include	O
some	O
kind	O
of	O
lossless	B-Algorithm
data	I-Algorithm
compression	I-Algorithm
.	O
</s>
<s>
There	O
are	O
several	O
algorithms	O
that	O
provide	O
similar	O
results	O
:	O
LZW	B-Algorithm
(	O
widely	O
supported	O
)	O
,	O
IDRC	O
(	O
Exabyte	O
)	O
,	O
ALDC	O
(	O
IBM	O
,	O
QIC	B-Device
)	O
and	O
DLZ1	O
(	O
DLT	B-Device
)	O
.	O
</s>
<s>
The	O
ratio	O
actually	O
obtained	O
depends	O
on	O
the	O
nature	O
of	O
the	O
data	O
so	O
the	O
compression	B-General_Concept
ratio	I-General_Concept
cannot	O
be	O
relied	O
upon	O
when	O
specifying	O
the	O
capacity	O
of	O
equipment	O
,	O
e.g.	O
,	O
a	O
drive	O
claiming	O
a	O
compressed	O
capacity	O
of	O
500GB	O
may	O
not	O
be	O
adequate	O
to	O
back	B-Protocol
up	I-Protocol
500GB	O
of	O
real	O
data	O
.	O
</s>
<s>
Software	O
compression	O
can	O
achieve	O
much	O
better	O
results	O
with	O
sparse	O
data	O
,	O
but	O
uses	O
the	O
host	O
computer	O
's	O
processor	O
,	O
and	O
can	O
slow	O
the	O
backup	B-Protocol
if	O
the	O
host	O
computer	O
is	O
unable	O
to	O
compress	O
as	O
fast	O
as	O
the	O
data	O
is	O
written	O
.	O
</s>
<s>
Plain	O
text	O
,	O
raw	O
images	O
,	O
and	O
database	O
files	O
(	O
TXT	B-General_Concept
,	O
ASCII	B-Protocol
,	O
BMP	B-Device
,	O
DBF	B-Application
,	O
etc	O
.	O
)	O
</s>
<s>
By	O
contrast	O
,	O
encrypted	O
data	O
and	O
pre-compressed	O
data	O
(	O
PGP	B-Application
,	O
ZIP	B-General_Concept
,	O
JPEG	O
,	O
MPEG	O
,	O
MP3	B-Application
,	O
etc	O
.	O
)	O
</s>
<s>
It	O
is	O
also	O
common	O
for	O
tape	O
cartridges	O
to	O
have	O
bar	O
codes	O
on	O
their	O
labels	O
in	O
order	O
to	O
assist	O
an	O
automated	O
tape	B-Device
library	I-Device
.	O
</s>
<s>
as	O
a	O
removable	O
medium	O
it	O
allows	O
the	O
creation	O
of	O
an	O
air	B-Architecture
gap	I-Architecture
that	O
can	O
prevent	O
data	O
from	O
being	O
hacked	O
,	O
encrypted	O
or	O
deleted	O
;	O
</s>
<s>
In	O
2014	O
,	O
Sony	O
and	O
IBM	O
announced	O
that	O
they	O
had	O
been	O
able	O
to	O
record	O
148	O
gigabits	O
per	O
square	O
inch	O
with	O
magnetic	O
tape	O
media	O
developed	O
using	O
a	O
new	O
vacuum	O
thin-film	O
forming	O
technology	O
able	O
to	O
form	O
extremely	O
fine	O
crystal	O
particles	O
,	O
,	O
a	O
tape	B-Architecture
storage	I-Architecture
technology	O
with	O
the	O
highest	O
reported	O
magnetic	O
tape	O
data	B-Device
density	I-Device
,	O
148Gbit/in²	O
(	O
23Gbit/cm²	O
)	O
,	O
potentially	O
allowing	O
a	O
native	O
tape	O
capacity	O
of	O
185TB	O
.	O
</s>
<s>
It	O
was	O
further	O
developed	O
by	O
Sony	O
,	O
with	O
announcement	O
in	O
2017	O
,	O
about	O
reported	O
data	B-Device
density	I-Device
of	O
201Gbit/in²	O
(	O
31Gbit/cm²	O
)	O
,	O
giving	O
standard	O
compressed	O
tape	O
capacity	O
of	O
330TB	O
.	O
</s>
<s>
In	O
May	O
2014	O
,	O
Fujifilm	O
followed	O
Sony	O
and	O
made	O
an	O
announcement	O
that	O
it	O
will	O
develop	O
a	O
154TB	O
tape	O
cartridge	O
in	O
conjunction	O
with	O
IBM	O
,	O
which	O
will	O
have	O
an	O
areal	B-Device
data	I-Device
storage	I-Device
density	I-Device
of	O
85.9	O
GBit/in²	O
(	O
13.3	O
billion	O
bits	O
per	O
cm²	O
)	O
on	O
linear	O
magnetic	O
particulate	O
tape	O
.	O
</s>
