<s>
Duplicati	B-Language
is	O
a	O
backup	B-Protocol
client	O
that	O
securely	O
stores	O
encrypted	O
,	O
incremental	B-General_Concept
,	O
compressed	O
remote	B-General_Concept
backups	I-General_Concept
of	O
local	O
files	O
on	O
cloud	O
storage	O
services	O
and	O
remote	O
file	O
servers	O
.	O
</s>
<s>
Duplicati	B-Language
supports	O
not	O
only	O
various	O
online	B-General_Concept
backup	I-General_Concept
services	I-General_Concept
like	O
OneDrive	B-Application
,	O
Amazon	B-General_Concept
S3	I-General_Concept
,	O
Backblaze	B-General_Concept
,	O
Rackspace	O
Cloud	O
Files	O
,	O
Tahoe	B-General_Concept
LAFS	I-General_Concept
,	O
and	O
Google	B-Application
Drive	I-Application
,	O
but	O
also	O
any	O
servers	O
that	O
support	O
SSH/SFTP	B-Protocol
,	O
WebDAV	B-Protocol
,	O
or	O
FTP	B-Protocol
.	O
</s>
<s>
Duplicati	B-Language
uses	O
standard	O
components	O
such	O
as	O
rdiff	B-Application
,	O
zip	B-General_Concept
,	O
AESCrypt	O
,	O
and	O
GnuPG	B-Application
.	O
</s>
<s>
This	O
allows	O
users	O
to	O
recover	O
backup	B-Protocol
files	O
even	O
if	O
Duplicati	B-Language
is	O
not	O
available	O
.	O
</s>
<s>
Released	O
under	O
the	O
terms	O
of	O
the	O
GNU	B-Application
Lesser	I-Application
General	I-Application
Public	I-Application
License	I-Application
(	O
LGPL	B-Application
)	O
,	O
Duplicati	B-Language
is	O
free	B-Application
software	I-Application
.	O
</s>
<s>
Duplicati	B-Language
is	O
written	O
mostly	O
in	O
C#	B-Application
and	O
implemented	O
completely	O
within	O
the	O
CLR	O
,	O
which	O
enables	O
it	O
to	O
be	O
cross-platform	O
.	O
</s>
<s>
It	O
runs	O
well	O
on	O
32-bit	O
and	O
64-bit	O
versions	O
on	O
Windows	O
,	O
macOS	B-Application
and	O
Linux	B-Application
using	O
either	O
.NET	B-Application
Framework	I-Application
or	O
Mono	B-Application
.	O
</s>
<s>
Duplicati	B-Language
has	O
both	O
a	O
graphical	B-Application
user	I-Application
interface	I-Application
with	O
a	O
wizard-style	O
interface	O
and	O
a	O
command-line	B-Application
version	O
for	O
use	O
in	O
headless	B-Application
environments	O
.	O
</s>
<s>
The	O
command-line	B-Application
version	O
is	O
similar	O
to	O
the	O
Duplicity	B-Application
interface	O
.	O
</s>
<s>
Duplicati	B-Language
has	O
some	O
unique	O
features	O
that	O
are	O
usually	O
only	O
found	O
in	O
commercial	O
systems	O
,	O
such	O
as	O
remote	O
verification	O
of	O
backup	B-Protocol
files	O
,	O
disk	O
snapshots	O
,	O
and	O
backup	B-Protocol
of	O
open	O
files	O
.	O
</s>
<s>
The	O
disk	O
snapshots	O
are	O
performed	O
with	O
VSS	O
on	O
Windows	O
and	O
LVM	B-Application
on	O
Linux	B-Application
.	O
</s>
<s>
The	O
original	O
Duplicati	B-Language
project	O
was	O
started	O
in	O
June	O
2008	O
and	O
intended	O
to	O
produce	O
a	O
graphical	B-Application
user	I-Application
interface	I-Application
for	O
the	O
Duplicity	B-Application
program	O
.	O
</s>
<s>
This	O
included	O
a	O
port	O
of	O
the	O
Duplicity	B-Application
code	O
for	O
use	O
on	O
Windows	O
,	O
but	O
was	O
dropped	O
in	O
September	O
2008	O
,	O
where	O
work	O
on	O
a	O
clean	O
re-implementation	O
began	O
.	O
</s>
<s>
This	O
re-implementation	O
includes	O
all	O
the	O
sub-programs	O
found	O
in	O
Duplicity	B-Application
,	O
such	O
as	O
rdiff	B-Application
,	O
ftp	B-Protocol
,	O
etc	O
.	O
</s>
<s>
This	O
initial	O
version	O
of	O
Duplicati	B-Language
saw	O
an	O
initial	O
release	O
in	O
June	O
2009	O
.	O
</s>
<s>
In	O
2012	O
,	O
work	O
on	O
Duplicati	B-Language
2	O
started	O
,	O
which	O
is	O
a	O
complete	O
rewrite	O
.	O
</s>
<s>
It	O
includes	O
a	O
new	O
storage	O
engine	O
that	O
allows	O
efficient	O
,	O
incremental	B-General_Concept
,	O
continuous	O
backups	B-Protocol
.	O
</s>
<s>
The	O
new	O
user	O
interface	O
is	O
web-based	O
,	O
which	O
makes	O
it	O
possible	O
to	O
install	O
Duplicati	B-Language
2	O
on	O
headless	B-Application
systems	I-Application
like	O
servers	O
or	O
a	O
NAS	B-Application
.	O
</s>
<s>
As	O
it	O
is	O
also	O
responsive	B-General_Concept
,	O
it	O
can	O
be	O
easily	O
used	O
on	O
mobile	O
devices	O
.	O
</s>
<s>
The	O
Duplicati	B-Language
GUI	B-Application
and	O
command-line	B-Application
interface	I-Application
both	O
call	O
a	O
common	O
component	O
called	O
Main	O
,	O
which	O
serves	O
as	O
a	O
binding	O
point	O
for	O
all	O
the	O
operations	O
supported	O
.	O
</s>
<s>
Currently	O
the	O
encryption	O
,	O
compression	O
and	O
storage	O
component	O
are	O
considered	O
subcomponent	O
and	O
are	O
loaded	O
at	O
runtime	O
,	O
making	O
it	O
possible	O
for	O
a	O
third-party	O
developer	O
to	O
inject	O
a	O
subcomponent	O
into	O
Duplicati	B-Language
without	O
access	O
to	O
the	O
source	O
or	O
any	O
need	O
to	O
modify	O
Duplicati	B-Language
itself	O
.	O
</s>
<s>
The	O
license	O
type	O
is	O
also	O
flexible	O
enough	O
to	O
allow	O
redistribution	O
of	O
Duplicati	B-Language
with	O
a	O
closed-source	B-Application
storage	O
provider	O
.	O
</s>
<s>
Duplicati	B-Language
is	O
designed	O
to	O
be	O
as	O
independent	O
of	O
the	O
provider	O
as	O
possible	O
,	O
which	O
means	O
that	O
any	O
storage	O
medium	O
that	O
supports	O
the	O
common	O
commands	O
(	O
GET	O
,	O
PUT	O
,	O
LIST	O
,	O
DELETE	O
)	O
can	O
work	O
with	O
Duplicati	B-Language
.	O
</s>
<s>
The	O
Duplicity	B-Application
model	O
,	O
on	O
which	O
Duplicati	B-Language
is	O
based	O
,	O
relies	O
heavily	O
on	O
components	O
in	O
the	O
system	O
,	O
such	O
as	O
librdiff	B-Application
,	O
TcFTP	O
and	O
others	O
.	O
</s>
<s>
Since	O
Duplicati	B-Language
is	O
intended	O
to	O
be	O
cross-platform	O
,	O
and	O
it	O
is	O
unlikely	O
that	O
all	O
those	O
components	O
are	O
available	O
on	O
all	O
platforms	O
,	O
Duplicati	B-Language
re-implements	O
the	O
components	O
instead	O
.	O
</s>
<s>
Most	O
notably	O
,	O
Duplicati	B-Language
features	O
an	O
rdiff	B-Application
and	O
AESCrypt	O
implementation	O
that	O
work	O
on	O
any	O
system	O
that	O
supports	O
a	O
Common	O
Language	O
Runtime	O
.	O
</s>
<s>
The	O
GUI	B-Application
frontend	O
in	O
Duplicati	B-Language
1.x	O
is	O
intended	O
to	O
be	O
used	O
on	O
a	O
single	O
machine	O
with	O
a	O
display	O
attached	O
.	O
</s>
<s>
However	O
,	O
it	O
is	O
also	O
possible	O
to	O
install	O
Duplicati	B-Language
as	O
a	O
Windows	O
service	O
or	O
Linux	B-Application
daemon	B-Operating_System
,	O
and	O
set	O
the	O
Duplicati	B-Language
system	O
tray	O
from	O
starting	O
the	O
Duplicati	B-Language
service	O
.	O
</s>
<s>
This	O
limitation	O
has	O
been	O
addressed	O
in	O
Duplicati	B-Language
2	O
,	O
which	O
has	O
a	O
web	O
interface	O
and	O
can	O
be	O
used	O
on	O
headless	B-Application
systems	I-Application
.	O
</s>
<s>
Duplicati	B-Language
1.x	O
has	O
extremely	O
slow	O
file	O
listings	O
,	O
so	O
browsing	O
a	O
file	O
tree	O
to	O
do	O
restores	O
can	O
take	O
a	O
long	O
time	O
.	O
</s>
<s>
Since	O
Duplicati	B-Language
produces	O
incremental	B-General_Concept
backups	I-General_Concept
,	O
a	O
corrupt	O
or	O
missing	O
incremental	B-General_Concept
volume	O
can	O
render	O
all	O
following	O
incremental	B-General_Concept
backups	I-General_Concept
(	O
up	O
to	O
the	O
next	O
full	B-Protocol
backup	I-Protocol
)	O
useless	O
.	O
</s>
<s>
Duplicati	B-Language
2	O
regularly	O
tests	O
the	O
backup	B-Protocol
to	O
detect	O
corrupted	O
files	O
early	O
.	O
</s>
<s>
Duplicati	B-Language
1.x	O
only	O
stores	O
the	O
file	O
modification	O
date	O
,	O
not	O
metadata	O
like	O
permissions	O
and	O
attributes	O
.	O
</s>
<s>
This	O
has	O
been	O
addressed	O
in	O
Duplicati	B-Language
2	O
.	O
</s>
