<s>
A	O
virtual	B-Device
tape	I-Device
library	I-Device
(	O
VTL	O
)	O
is	O
a	O
data	B-General_Concept
storage	I-General_Concept
virtualization	B-Application
technology	O
used	O
typically	O
for	O
backup	B-Protocol
and	I-Protocol
recovery	I-Protocol
purposes	O
.	O
</s>
<s>
A	O
VTL	O
presents	O
a	O
storage	O
component	O
(	O
usually	O
hard	O
disk	O
storage	O
)	O
as	O
tape	B-Device
libraries	I-Device
or	O
tape	O
drives	O
for	O
use	O
with	O
existing	O
backup	B-Application
software	I-Application
.	O
</s>
<s>
Virtualizing	O
the	O
disk	O
storage	O
as	O
tape	O
allows	O
integration	O
of	O
VTLs	O
with	O
existing	O
backup	B-Application
software	I-Application
and	O
existing	O
backup	B-Protocol
and	I-Protocol
recovery	I-Protocol
processes	O
and	O
policies	O
.	O
</s>
<s>
The	O
benefits	O
of	O
such	O
virtualization	B-Application
include	O
storage	O
consolidation	O
and	O
faster	O
data	O
restore	O
processes	O
.	O
</s>
<s>
For	O
most	O
mainframe	B-Architecture
data	O
centers	O
,	O
the	O
storage	B-General_Concept
capacity	I-General_Concept
varies	O
,	O
however	O
protecting	O
its	O
business	O
and	O
mission	O
critical	O
data	O
is	O
always	O
vital	O
.	O
</s>
<s>
Most	O
current	O
VTL	O
solutions	O
use	O
SAS	O
or	O
SATA	O
disk	B-General_Concept
arrays	I-General_Concept
as	O
the	O
primary	O
storage	O
component	O
due	O
to	O
their	O
relatively	O
low	O
cost	O
.	O
</s>
<s>
The	O
use	O
of	O
array	O
enclosures	O
increases	O
the	O
scalability	O
of	O
the	O
solution	O
by	O
allowing	O
the	O
addition	O
of	O
more	O
disk	O
drives	O
and	O
enclosures	O
to	O
increase	O
the	O
storage	B-General_Concept
capacity	I-General_Concept
.	O
</s>
<s>
By	O
backing	O
up	O
data	O
to	O
disks	O
instead	O
of	O
tapes	O
,	O
VTL	O
often	O
increases	O
performance	O
of	O
both	O
backup	B-Protocol
and	I-Protocol
recovery	I-Protocol
operations	O
.	O
</s>
<s>
Restore	O
processes	O
are	O
found	O
to	O
be	O
faster	O
than	O
backup	B-Protocol
regardless	O
of	O
implementations	O
.	O
</s>
<s>
In	O
some	O
cases	O
,	O
the	O
data	O
stored	O
on	O
the	O
VTL	O
's	O
disk	B-General_Concept
array	I-General_Concept
is	O
exported	O
to	O
other	O
media	O
,	O
such	O
as	O
physical	O
tapes	O
,	O
for	O
disaster	B-General_Concept
recovery	I-General_Concept
purposes	O
(	O
scheme	O
called	O
disk-to-disk-to-tape	B-General_Concept
,	O
or	O
D2D2T	B-General_Concept
)	O
.	O
</s>
<s>
Alternatively	O
,	O
most	O
contemporary	O
backup	B-Application
software	I-Application
products	O
introduced	O
also	O
direct	O
usage	O
of	O
the	O
file	B-Application
system	I-Application
storage	O
(	O
especially	O
network-attached	B-Application
storage	I-Application
,	O
accessed	O
through	O
NFS	B-Protocol
and	O
CIFS	B-Operating_System
protocols	I-Operating_System
over	O
IP	B-Protocol
networks	O
)	O
not	O
requiring	O
a	O
tape	B-Device
library	I-Device
emulation	O
at	O
all	O
.	O
</s>
<s>
They	O
also	O
often	O
offer	O
a	O
disk	B-General_Concept
staging	I-General_Concept
feature	O
:	O
moving	O
the	O
data	O
from	O
disk	O
to	O
a	O
physical	O
tape	O
for	O
a	O
long-term	O
storage	O
.	O
</s>
<s>
While	O
a	O
virtual	B-Device
tape	I-Device
library	I-Device
is	O
very	O
fast	O
,	O
the	O
disk	O
storage	O
within	O
is	O
not	O
designed	O
to	O
be	O
removable	O
,	O
and	O
does	O
not	O
usually	O
involve	O
physically	O
removable	O
external	O
disk	O
drives	O
to	O
be	O
used	O
for	O
data	O
archiving	O
in	O
place	O
of	O
tape	O
.	O
</s>
<s>
Later	O
,	O
IBM	O
released	O
a	O
Virtual	B-Device
Tape	I-Device
Server	O
(	O
VTS	O
)	O
introduced	O
in	O
1997	O
.	O
</s>
<s>
It	O
was	O
targeted	O
for	O
a	O
mainframe	B-Architecture
market	O
,	O
where	O
many	O
legacy	O
applications	O
tend	O
to	O
use	O
a	O
lot	O
of	O
very	O
short	O
tape	O
volumes	O
.	O
</s>
<s>
It	O
used	O
the	O
ESCON	B-Device
interface	O
,	O
and	O
acted	O
as	O
a	O
disk	O
cache	O
for	O
the	O
IBM	O
3494	O
tape	B-Device
library	I-Device
.	O
</s>
<s>
Other	O
offerings	O
in	O
the	O
mainframe	B-Architecture
space	O
are	O
also	O
"	O
tapeless	O
"	O
.	O
</s>
<s>
DLm	O
has	O
been	O
developed	O
by	O
EMC	O
Corporation	O
,	O
while	O
Luminex	O
has	O
gained	O
popularity	O
and	O
wide	O
acceptance	O
by	O
teaming	O
with	O
Data	O
Domain	O
to	O
provide	O
the	O
benefits	O
of	O
data	B-General_Concept
deduplication	I-General_Concept
behind	O
its	O
Channel	O
Gateway	O
platform	O
.	O
</s>
<s>
With	O
the	O
consequent	O
reduction	O
in	O
off-site	O
replication	O
bandwidth	O
afforded	O
by	O
deduplication	O
,	O
it	O
is	O
possible	O
and	O
practical	O
for	O
this	O
form	O
of	O
virtual	B-Device
tape	I-Device
to	O
reduce	O
recovery	O
point	O
objective	O
time	O
and	O
recovery	O
time	O
objective	O
to	O
near	O
zero	O
(	O
or	O
instantaneous	O
)	O
.	O
</s>
<s>
Outside	O
of	O
the	O
mainframe	B-Architecture
environment	O
,	O
tape	O
drives	O
and	O
libraries	O
mostly	O
featured	O
SCSI	B-Architecture
.	O
</s>
<s>
Likewise	O
,	O
VTLs	O
were	O
developed	O
supporting	O
popular	O
SCSI	B-Architecture
transport	O
protocols	O
such	O
as	O
SPI	O
(	O
legacy	O
systems	O
)	O
,	O
Fibre	B-Architecture
Channel	I-Architecture
,	O
and	O
iSCSI	B-Protocol
.	O
</s>
<s>
In	O
mid-2010s	O
VTLs	O
got	O
a	O
rebirth	O
thanks	O
to	O
hi-capacity	O
"	O
archive	O
"	O
drives	O
from	O
Seagate	O
and	O
HGST	O
and	O
more	O
popular	O
"	O
tape	O
in	O
cloud	O
"	O
and	O
Disk-to-Disk-to-Tape	B-General_Concept
(	O
often	O
in	O
cloud	O
)	O
scenarios	O
.	O
</s>
<s>
Amazon	B-Application
and	O
StarWind	O
Software	O
in	O
partnership	O
with	O
Veeam	O
,	O
BackBlaze	B-General_Concept
and	O
Wasabi	B-General_Concept
Technologies	I-General_Concept
offer	O
a	O
so-called	O
gateway	O
products	O
that	O
facilitates	O
backing	O
up	O
and	O
archiving	O
"	O
on	O
premises	O
"	O
data	O
as	O
virtual	B-Device
tapes	I-Device
stored	O
in	O
AWS	B-Application
,	O
Microsoft	B-Application
Azure	I-Application
,	O
Wasabi	B-General_Concept
Technologies	I-General_Concept
and	O
BackBlaze	B-General_Concept
public	O
clouds	O
.	O
</s>
<s>
The	O
idea	O
is	O
to	O
provide	O
a	O
seamless	O
integration	O
of	O
a	O
backup	B-Protocol
applications	O
incompatible	O
with	O
the	O
APIs	O
object	O
storages	O
expose	O
.	O
</s>
<s>
Say	O
,	O
at	O
the	O
time	O
Veeam	O
could	O
n't	O
do	O
AWS	B-General_Concept
S3	I-General_Concept
and	O
ca	O
n't	O
backup	B-Protocol
to	O
the	O
deep	O
archive	O
tier	O
within	O
Azure	B-Application
still	O
.	O
</s>
