<s>
rdiff-backup	B-Application
is	O
a	O
backup	B-Protocol
software	O
written	O
in	O
Python	B-Language
that	O
creates	O
reverse	O
incremental	O
backups	B-Protocol
.	O
</s>
<s>
The	O
most	O
recent	O
backup	B-Protocol
is	O
thus	O
directly	O
accessible	O
,	O
while	O
earlier	O
backups	B-Protocol
will	O
be	O
reconstructed	O
from	O
diff	B-Application
files	O
by	O
rdiff-backup	B-Application
.	O
</s>
<s>
As	O
the	O
name	O
implies	O
,	O
rdiff-backup	B-Application
uses	O
the	O
rdiff	B-Application
method	O
(	O
more	O
exactly	O
,	O
the	O
reimplementation	O
of	O
rsync	B-Application
within	O
librsync	B-Application
)	O
to	O
compute	O
the	O
differences	O
between	O
file	O
versions	O
.	O
</s>
<s>
rdiff-backup	B-Application
is	O
able	O
to	O
back	B-Protocol
up	I-Protocol
files	O
across	O
different	O
machines	O
via	O
ssh	B-Protocol
.	O
</s>
<s>
Normal	O
operation	O
is	O
rdiff-backup	B-Application
<source directory> <backup directory>	O
.	O
</s>
<s>
gzip	B-Application
compression	I-Application
of	O
increment	O
files	O
can	O
be	O
disabled	O
with	O
--no-compression	O
.	O
</s>
<s>
The	O
options	O
-v	O
5	O
--print-statistics	O
show	O
the	O
backup	B-Protocol
's	O
progress	O
and	O
some	O
statistics	O
.	O
</s>
<s>
Specifying	O
--no-fsync	O
will	O
disable	O
fsync	B-Language
,	O
causing	O
a	O
significant	O
speedup	O
,	O
with	O
an	O
elevated	O
risk	O
of	O
data	O
loss	O
.	O
</s>
<s>
rdiff-backup	B-Application
--restore-as-of	O
<date> <backup> <source> will restore to <source>	O
the	O
entire	O
backup	B-Protocol
,	O
a	O
single	O
file	O
or	O
a	O
sub-directory	O
.	O
</s>
<s>
or	O
"	O
now	O
"	O
,	O
which	O
will	O
restore	O
the	O
most	O
recent	O
backup	B-Protocol
.	O
</s>
<s>
It	O
is	O
also	O
possible	O
to	O
find	O
the	O
relevant	O
time-stamped	O
file	O
in	O
the	O
rdiff-backup-data/increments	O
directory	O
,	O
and	O
run	O
rdiff-backup	B-Application
<time-stamped file> <file or folder to be restored>	O
.	O
</s>
<s>
Simpler	O
(	O
but	O
not	O
always	O
correctly	O
,	O
as	O
the	O
file	O
permissions	O
might	O
not	O
be	O
properly	O
restored	O
)	O
,	O
the	O
most	O
recent	O
backup	B-Protocol
can	O
also	O
be	O
restored	O
by	O
copying	O
a	O
back-upped	O
file	O
or	O
directory	O
with	O
cp	B-Application
-a	O
or	O
rsync	B-Application
-a	O
.	O
</s>
<s>
A	O
deleted	O
file	O
–	O
recognizable	O
by	O
the	O
suffix	O
snapshot.gz	O
–	O
can	O
also	O
be	O
restored	O
by	O
retrieving	O
it	O
in	O
the	O
rdiff-backup-data/increments	O
directory	O
,	O
copying	O
it	O
to	O
the	O
source	O
directory	O
,	O
and	O
unpacking	O
with	O
gzip	B-Application
.	O
</s>
<s>
Only	O
the	O
oldest	O
backups	B-Protocol
can	O
be	O
removed	O
,	O
with	O
rdiff-backup	B-Application
--remove-older-than	O
<date> <backup directory>	O
.	O
</s>
<s>
rdiff-backup	B-Application
does	O
not	O
work	O
under	O
Linux	O
with	O
exFAT	B-Application
file	I-Application
systems	I-Application
,	O
though	O
FAT	B-Application
and	O
NTFS	B-Application
do	O
work	O
.	O
</s>
<s>
This	O
is	O
mostly	O
due	O
to	O
the	O
implementation	O
as	O
FUSE	B-Application
module	O
,	O
causing	O
delays	O
in	O
certain	O
operations	O
,	O
making	O
it	O
probably	O
unfit	O
for	O
backup	B-Protocol
purposes	O
.	O
</s>
<s>
No	O
file	O
system	O
is	O
explicitly	O
supported	O
or	O
unsupported	O
,	O
but	O
rdiff-backup	B-Application
does	O
tests	O
before	O
starting	O
a	O
backup	B-Protocol
,	O
and	O
refuses	O
to	O
progress	O
on	O
file	O
systems	O
deemed	O
unfit	O
.	O
</s>
<s>
By	O
using	O
the	O
newer	O
in-kernel	O
exFAT-driver	O
,	O
this	O
limitation	O
should	O
be	O
overcome	O
.	O
</s>
<s>
rdiff-backup	B-Application
recognizes	O
changed	O
files	O
only	O
by	O
file	O
size	O
as	O
well	O
as	O
modification	O
time	O
(	O
mtime	B-Language
)	O
.	O
</s>
<s>
To	O
make	O
sure	O
all	O
changed	O
files	O
have	O
been	O
back-upped	O
,	O
running	O
rdiff-backup	B-Application
--compare-hash	O
<source directory> <backup directory> ( or rdiff-backup --compare-full <source directory> <backup directory>	O
for	O
a	O
byte-wise	O
comparison	O
)	O
will	O
display	O
all	O
changed	O
files	O
.	O
</s>
<s>
Then	O
,	O
using	O
touch	B-Application
,	O
the	O
modification	O
time	O
of	O
all	O
problematic	O
files	O
can	O
be	O
reset	O
to	O
now	O
,	O
and	O
thus	O
,	O
they	O
will	O
be	O
included	O
during	O
the	O
next	O
rdiff-backup	B-Application
run	O
.	O
</s>
