<s>
Disk	B-General_Concept
staging	I-General_Concept
is	O
using	O
disks	B-Device
as	O
an	O
additional	O
,	O
temporary	O
stage	O
of	O
backup	B-Protocol
process	O
before	O
finally	O
storing	O
backup	B-Protocol
to	O
tape	B-Architecture
.	O
</s>
<s>
Backups	B-Protocol
stay	O
on	O
disk	O
typically	O
for	O
a	O
day	O
or	O
a	O
week	O
,	O
before	O
being	O
copied	O
to	O
tape	B-Architecture
in	O
a	O
background	O
process	O
and	O
deleted	O
afterwards	O
.	O
</s>
<s>
The	O
process	O
of	O
disk	B-General_Concept
staging	I-General_Concept
is	O
controlled	O
by	O
the	O
same	O
software	O
that	O
performs	O
actual	O
backups	B-Protocol
,	O
which	O
is	O
different	O
from	O
virtual	B-Device
tape	I-Device
library	I-Device
where	O
intermediate	O
disk	O
usage	O
is	O
hidden	O
from	O
main	O
backup	B-Protocol
software	O
.	O
</s>
<s>
Both	O
techniques	O
are	O
known	O
as	O
D2D2T	B-General_Concept
(	O
disk-to-disk-to-tape	B-General_Concept
)	O
.	O
</s>
<s>
But	O
if	O
the	O
data	O
exists	O
only	O
on	O
tape	B-Architecture
it	O
is	O
restored	O
directly	O
(	O
no	O
backward-staging	O
on	O
restore	O
)	O
.	O
</s>
<s>
Reasons	O
behind	O
using	O
D2D2T	B-General_Concept
:	O
</s>
