<s>
Resilient	B-Application
File	I-Application
System	I-Application
(	O
ReFS	B-Application
)	O
,	O
codenamed	O
"	O
Protogon	B-Application
"	O
,	O
is	O
a	O
Microsoft	O
proprietary	B-Application
file	B-Application
system	I-Application
introduced	O
with	O
Windows	B-Device
Server	I-Device
2012	I-Device
with	O
the	O
intent	O
of	O
becoming	O
the	O
"	O
next	O
generation	O
"	O
file	B-Application
system	I-Application
after	O
NTFS	B-Application
.	O
</s>
<s>
ReFS	B-Application
was	O
designed	O
to	O
overcome	O
problems	O
that	O
had	O
become	O
significant	O
over	O
the	O
years	O
since	O
NTFS	B-Application
was	O
conceived	O
,	O
which	O
are	O
related	O
to	O
how	O
data	O
storage	O
requirements	O
had	O
changed	O
.	O
</s>
<s>
As	O
a	O
result	O
,	O
the	O
file	B-Application
system	I-Application
needs	O
to	O
be	O
self-repairing	O
(	O
to	O
prevent	O
disk	B-Device
checking	I-Device
from	O
being	O
impractically	O
slow	O
or	O
disruptive	O
)	O
,	O
along	O
with	O
abstraction	B-Architecture
or	O
virtualization	B-General_Concept
between	O
physical	O
disks	O
and	O
logical	B-Application
volumes	I-Application
.	O
</s>
<s>
The	O
key	O
design	O
advantages	O
of	O
ReFS	B-Application
include	O
automatic	O
integrity	O
checking	O
and	O
data	B-Error_Name
scrubbing	I-Error_Name
,	O
elimination	O
of	O
the	O
need	O
for	O
running	O
chkdsk	B-Device
,	O
protection	O
against	O
data	O
degradation	O
,	O
built-in	O
handling	O
of	O
hard	B-Device
disk	I-Device
drive	I-Device
failure	I-Device
and	O
redundancy	O
,	O
integration	O
of	O
RAID	B-Architecture
functionality	O
,	O
a	O
switch	O
to	O
copy/allocate	B-Language
on	I-Language
write	I-Language
for	O
data	O
and	O
metadata	O
updates	O
,	O
handling	O
of	O
very	O
long	O
paths	O
and	O
filenames	O
,	O
and	O
storage	B-Application
virtualization	I-Application
and	O
pooling	O
,	O
including	O
almost	O
arbitrarily	O
sized	O
logical	B-Application
volumes	I-Application
(	O
unrelated	O
to	O
the	O
physical	O
sizes	O
of	O
the	O
used	O
drives	O
)	O
.	O
</s>
<s>
Improved	O
reliability	O
for	O
on-disk	O
structures	O
ReFS	B-Application
uses	O
B+	O
trees	O
for	O
all	O
on-disk	O
structures	O
,	O
including	O
all	O
metadata	O
and	O
file	O
data	O
.	O
</s>
<s>
Metadata	O
and	O
file	O
data	O
are	O
organized	O
into	O
tables	O
similar	O
to	O
a	O
relational	B-Application
database	I-Application
.	O
</s>
<s>
The	O
file	O
size	O
,	O
number	O
of	O
files	O
in	O
a	O
folder	O
,	O
total	O
volume	O
size	O
and	O
number	O
of	O
folders	O
in	O
a	O
volume	O
are	O
limited	O
by	O
64-bit	O
numbers	O
;	O
as	O
a	O
result	O
,	O
ReFS	B-Application
supports	O
a	O
maximum	O
file	O
size	O
of	O
16	O
exbibytes	O
(	O
264−1	O
bytes	O
)	O
,	O
and	O
a	O
maximum	O
volume	O
size	O
of	O
35	O
petabytes	O
.	O
</s>
<s>
Built-in	O
resilience	O
ReFS	B-Application
employs	O
an	O
allocation-on-write	B-Language
update	O
strategy	O
for	O
metadata	O
,	O
which	O
allocates	O
new	O
chunks	O
for	O
every	O
update	O
transaction	O
and	O
uses	O
large	O
IO	B-General_Concept
batches	O
.	O
</s>
<s>
All	O
ReFS	B-Application
metadata	O
have	O
64-bit	O
checksums	O
which	O
are	O
stored	O
independently	O
.	O
</s>
<s>
The	O
file	O
data	O
can	O
have	O
an	O
optional	O
checksum	O
in	O
a	O
separate	O
"	O
integrity	O
stream	B-Application
"	O
,	O
in	O
which	O
case	O
the	O
file	O
update	O
strategy	O
also	O
implements	O
allocation-on-write	B-Language
for	O
file	O
data	O
;	O
this	O
is	O
controlled	O
by	O
a	O
new	O
"	O
integrity	O
"	O
attribute	O
applicable	O
to	O
both	O
files	O
and	O
directories	O
.	O
</s>
<s>
As	O
a	O
result	O
of	O
built-in	O
resiliency	O
,	O
administrators	O
do	O
not	O
need	O
to	O
periodically	O
run	O
error-checking	O
tools	O
such	O
as	O
CHKDSK	B-Device
when	O
using	O
ReFS	B-Application
.	O
</s>
<s>
Compatibility	O
with	O
existing	O
APIs	O
and	O
technologies	O
ReFS	B-Application
supports	O
only	O
a	O
subset	O
of	O
NTFS	B-Application
features	O
and	O
only	O
Win32	O
APIs	O
that	O
are	O
"	O
widely	O
adopted	O
"	O
but	O
does	O
not	O
require	O
new	O
system	O
APIs	O
,	O
and	O
most	O
file	B-Application
system	I-Application
filters	O
continue	O
to	O
work	O
with	O
ReFS	B-Application
volumes	O
.	O
</s>
<s>
ReFS	B-Application
supports	O
many	O
existing	O
Windows	O
and	O
NTFS	B-Application
features	O
such	O
as	O
BitLocker	O
encryption	O
,	O
Access	O
Control	O
Lists	O
,	O
USN	B-Application
Journal	I-Application
,	O
change	O
notifications	O
,	O
symbolic	O
links	O
,	O
junction	O
points	O
,	O
mount	O
points	O
,	O
reparse	B-Application
points	I-Application
,	O
volume	O
snapshots	O
,	O
file	O
IDs	O
,	O
and	O
oplock	O
.	O
</s>
<s>
ReFS	B-Application
seamlessly	O
integrates	O
with	O
Storage	O
Spaces	O
,	O
a	O
storage	B-Application
virtualization	I-Application
layer	O
that	O
allows	O
data	O
mirroring	O
and	O
striping	O
,	O
as	O
well	O
as	O
sharing	O
storage	O
pools	O
between	O
machines	O
.	O
</s>
<s>
ReFS	B-Application
resiliency	O
features	O
enhance	O
the	O
mirroring	O
feature	O
provided	O
by	O
Storage	O
Spaces	O
and	O
can	O
detect	O
whether	O
any	O
mirrored	O
copies	O
of	O
files	O
become	O
corrupt	O
using	O
a	O
data	B-Error_Name
scrubbing	I-Error_Name
process	O
,	O
which	O
periodically	O
reads	O
all	O
mirror	O
copies	O
and	O
verifies	O
their	O
checksums	O
,	O
then	O
replaces	O
bad	O
copies	O
with	O
good	O
ones	O
.	O
</s>
<s>
Microsoft	O
Windows	O
and	O
Windows	B-Device
Server	I-Device
include	O
,	O
a	O
command-line	B-Application
utility	O
that	O
can	O
be	O
used	O
to	O
diagnose	O
heavily	O
damaged	O
ReFS	B-Application
volumes	O
,	O
identify	O
remaining	O
files	O
,	O
and	O
copy	O
those	O
files	O
to	O
another	O
volume	O
.	O
</s>
<s>
Some	O
NTFS	B-Application
features	O
are	O
not	O
implemented	O
in	O
ReFS	B-Application
.	O
</s>
<s>
These	O
include	O
object	O
IDs	O
,	O
8.3	O
filename	O
,	O
NTFS	B-Application
compression	O
,	O
Encrypting	O
File	B-Application
System	I-Application
(	O
EFS	O
)	O
,	O
transactional	O
NTFS	B-Application
,	O
extended	B-Application
attributes	I-Application
,	O
and	O
disk	B-Application
quotas	I-Application
.	O
</s>
<s>
Data	B-General_Concept
deduplication	I-General_Concept
was	O
missing	O
in	O
early	O
versions	O
of	O
ReFS	B-Application
.	O
</s>
<s>
It	O
was	O
implemented	O
in	O
v3.2	O
,	O
debuting	O
in	O
Windows	B-Device
Server	I-Device
v1709	O
.	O
</s>
<s>
Support	O
for	O
alternate	O
data	O
streams	O
and	O
hard	B-Application
links	I-Application
was	O
initially	O
not	O
implemented	O
in	O
ReFS	B-Application
.	O
</s>
<s>
In	O
Windows	B-Device
8.1	I-Device
64-bit	O
and	O
Server	B-Device
2012	I-Device
R2	O
,	O
the	O
file	B-Application
system	I-Application
reacquired	O
support	O
for	O
alternate	O
data	O
streams	O
,	O
with	O
lengths	O
of	O
up	O
to	O
128K	O
,	O
and	O
automatic	O
correction	O
of	O
corruption	O
when	O
integrity	O
streams	O
are	O
used	O
on	O
parity	O
spaces	O
.	O
</s>
<s>
ReFS	B-Application
had	O
initially	O
been	O
unsuitable	O
for	O
Microsoft	B-Application
SQL	I-Application
Server	I-Application
instance	O
allocation	O
due	O
to	O
the	O
absence	O
of	O
alternate	O
data	O
streams	O
.	O
</s>
<s>
Hard	B-Application
links	I-Application
were	O
introduced	O
with	O
preview	O
versions	O
of	O
Windows	B-Device
Server	I-Device
2022	I-Device
.	O
</s>
<s>
ReFS	B-Application
was	O
initially	O
added	O
to	O
Windows	B-Device
Server	I-Device
2012	I-Device
only	O
,	O
with	O
the	O
aim	O
of	O
gradual	O
migration	O
to	O
consumer	O
systems	O
in	O
future	O
versions	O
;	O
this	O
was	O
achieved	O
as	O
of	O
Windows	B-Device
8.1	I-Device
.	O
</s>
<s>
The	O
initial	O
versions	O
removed	O
some	O
NTFS	B-Application
features	O
,	O
such	O
as	O
disk	B-Application
quotas	I-Application
,	O
alternate	O
data	O
streams	O
,	O
and	O
extended	B-Application
attributes	I-Application
.	O
</s>
<s>
Some	O
of	O
these	O
were	O
re-implemented	O
in	O
later	O
versions	O
of	O
ReFS	B-Application
.	O
</s>
<s>
In	O
early	O
versions	O
(	O
2012	O
–	O
2013	O
)	O
,	O
ReFS	B-Application
was	O
similar	O
to	O
or	O
slightly	O
faster	O
than	O
NTFS	B-Application
in	O
most	O
tests	O
,	O
but	O
far	O
slower	O
when	O
full	O
integrity	O
checking	O
was	O
enabled	O
,	O
a	O
result	O
attributed	O
to	O
the	O
relative	O
newness	O
of	O
ReFS	B-Application
.	O
</s>
<s>
The	O
ability	O
to	O
create	O
ReFS	B-Application
volumes	O
was	O
removed	O
in	O
Windows	O
10	O
's	O
2017	O
Fall	O
Creators	O
Update	O
for	O
all	O
editions	O
except	O
Enterprise	O
and	O
Pro	O
for	O
Workstations	O
.	O
</s>
<s>
Starting	O
with	O
Windows	B-Device
Server	I-Device
2022	I-Device
and	O
Windows	B-Application
11	I-Application
v21H2	O
,	O
its	O
bootx64.efi	O
natively	O
supports	O
the	O
ReFS	B-Application
boot	O
feature	O
,	O
and	O
allows	O
the	O
system	O
to	O
be	O
installed	O
and	O
run	O
in	O
a	O
special	O
way	O
on	O
a	O
volume	O
formatted	O
with	O
ReFS	B-Application
v3	O
.	O
</s>
<s>
If	O
it	O
is	O
a	O
volume	O
formatted	O
with	O
ReFS	B-Application
v1	O
,	O
it	O
cannot	O
be	O
booted	O
with	O
ReFS	B-Application
.	O
</s>
<s>
The	O
cluster	B-Application
size	I-Application
of	O
a	O
ReFS	B-Application
volume	O
is	O
either	O
4KB	O
or	O
64KB	O
.	O
</s>
<s>
ReFS	B-Application
has	O
some	O
different	O
versions	O
,	O
with	O
various	O
degrees	O
of	O
compatibility	O
between	O
operating	O
system	O
versions	O
.	O
</s>
<s>
Aside	O
for	O
development	O
versions	O
of	O
the	O
filesystem	B-Application
,	O
usually	O
,	O
later	O
operating	O
system	O
versions	O
can	O
mount	O
filesystems	B-Application
created	O
with	O
earlier	O
OS	O
versions	O
(	O
backwards	O
compatibility	O
)	O
.	O
</s>
<s>
The	O
version	O
,	O
cluster	B-Application
size	I-Application
and	O
other	O
features	O
of	O
the	O
filesystem	B-Application
can	O
be	O
queried	O
with	O
the	O
command	O
fsutil	O
fsinfo	O
refsinfo	O
volumename	O
.	O
</s>
<s>
1.1	O
:	O
The	O
original	O
version	O
,	O
formatted	O
by	O
Windows	B-Device
Server	I-Device
2012	I-Device
.	O
</s>
<s>
1.2	O
:	O
Default	O
version	O
if	O
formatted	O
by	O
Windows	B-Device
8.1	I-Device
,	O
Windows	O
10	O
v1507	O
to	O
v1607	O
,	O
Windows	B-Device
Server	I-Device
2012	I-Device
R2	O
,	O
and	O
when	O
specified	O
ReFSv1	O
on	O
Windows	B-Device
Server	I-Device
2016	I-Device
.	O
</s>
<s>
Can	O
use	O
alternate	O
data	O
streams	O
under	O
Windows	B-Device
Server	I-Device
2012	I-Device
R2	O
.	O
</s>
<s>
2.0	O
:	O
Default	O
version	O
formatted	O
by	O
Windows	B-Device
Server	I-Device
2016	I-Device
TP2	O
and	O
TP3	O
.	O
</s>
<s>
Could	O
not	O
be	O
mounted	O
in	O
Windows	O
10	O
Build	O
10130	O
and	O
later	O
,	O
or	O
Windows	B-Device
Server	I-Device
2016	I-Device
TP4	O
and	O
later	O
.	O
</s>
<s>
3.0	O
:	O
Default	O
version	O
formatted	O
by	O
Windows	B-Device
Server	I-Device
2016	I-Device
TP4	O
and	O
TP5	O
.	O
</s>
<s>
3.1	O
:	O
Default	O
version	O
formatted	O
by	O
Windows	B-Device
Server	I-Device
2016	I-Device
RTM	O
.	O
</s>
<s>
3.2	O
:	O
Default	O
version	O
formatted	O
by	O
Windows	O
10	O
v1703	O
and	O
Windows	B-Device
Server	I-Device
Insider	O
Preview	O
build	O
16237	O
.	O
</s>
<s>
3.3	O
:	O
Default	O
version	O
formatted	O
by	O
Windows	O
10	O
Enterprise	O
v1709	O
(	O
ReFS	B-Application
volume	O
creation	O
ability	O
removed	O
from	O
all	O
editions	O
except	O
Enterprise	O
and	O
Pro	O
for	O
Workstations	O
starting	O
with	O
build	O
16226	O
;	O
read/write	O
ability	O
remains	O
)	O
and	O
Windows	B-Device
Server	I-Device
version	O
1709	O
(	O
starting	O
with	O
Windows	O
10	O
Enterprise	O
Insider	O
Preview	O
build	O
16257	O
and	O
Windows	B-Device
Server	I-Device
Insider	O
Preview	O
build	O
16257	O
)	O
.	O
</s>
<s>
3.4	O
:	O
Default	O
version	O
formatted	O
by	O
Windows	O
10	O
Pro	O
for	O
Workstations/Enterprise	O
v1803	O
and	O
newer	O
,	O
also	O
server	O
versions	O
(	O
including	O
the	O
long-time	O
support	O
version	O
Windows	B-Device
Server	I-Device
2019	O
)	O
.	O
</s>
<s>
3.5	O
:	O
Default	O
version	O
formatted	O
by	O
Windows	O
10	O
Enterprise	O
Insider	O
Preview	O
(	O
build	O
19536	O
or	O
newer	O
)	O
;	O
adds	O
support	O
for	O
hard	B-Application
links	I-Application
(	O
only	O
on	O
fresh	O
formatted	O
volume	O
;	O
not	O
supported	O
on	O
volumes	O
upgraded	O
from	O
previous	O
versions	O
)	O
.	O
</s>
<s>
3.7	O
:	O
Default	O
version	O
formatted	O
by	O
Windows	O
10	O
Enterprise	O
Insider	O
Preview	O
(	O
build	O
21313	O
or	O
newer	O
)	O
and	O
Windows	B-Device
Server	I-Device
Insider	O
Preview	O
(	O
build	O
20303	O
or	O
newer	O
)	O
.	O
</s>
<s>
Also	O
,	O
the	O
version	O
used	O
by	O
Windows	B-Device
Server	I-Device
2022	I-Device
and	O
Windows	B-Application
11	I-Application
.	O
</s>
<s>
Issues	O
identified	O
or	O
suggested	O
for	O
ReFS	B-Application
,	O
when	O
running	O
on	O
Storage	O
Spaces	O
,	O
include	O
:	O
</s>
<s>
Adding	O
thin-provisioned	O
ReFS	B-Application
on	O
top	O
of	O
Storage	O
Spaces	O
(	O
according	O
to	O
a	O
2012	O
pre-release	O
article	O
)	O
can	O
fail	O
in	O
a	O
non-graceful	O
manner	O
,	O
in	O
which	O
the	O
volume	O
without	O
warning	O
becomes	O
inaccessible	O
or	O
unmanageable	O
.	O
</s>
<s>
Smallnetbuilder	O
comments	O
that	O
,	O
in	O
such	O
cases	O
,	O
recovery	O
could	O
be	O
"	O
prohibitive	O
"	O
as	O
a	O
"	O
breakthrough	O
in	O
theory	O
"	O
is	O
needed	O
to	O
identify	O
storage	O
space	O
layouts	O
and	O
recover	O
them	O
,	O
which	O
is	O
required	O
before	O
any	O
ReFS	B-Application
recovery	O
of	O
file	B-Application
system	I-Application
contents	O
can	O
be	O
started	O
;	O
therefore	O
it	O
recommends	O
using	O
backups	O
as	O
well	O
.	O
</s>
<s>
Thin-provisioned	O
ReFS	B-Application
on	O
top	O
of	O
Storage	O
Spaces	O
,	O
occasionally	O
if	O
the	O
ReFS	B-Application
partition	O
is	O
extended	O
to	O
the	O
full	O
size	O
of	O
the	O
thin-volume	O
.	O
</s>
<s>
When	O
later	O
extending	O
the	O
thin-volume	O
size	O
the	O
ReFS	B-Application
partition	O
may	O
fail	O
to	O
extend	O
to	O
the	O
thin-volume	O
size	O
.	O
</s>
<s>
The	O
workaround	O
is	O
to	O
never	O
extend	O
the	O
ReFS	B-Application
partition	O
to	O
the	O
full	O
size	O
of	O
the	O
thin-volume	O
,	O
always	O
leave	O
a	O
few	O
GB	O
at	O
the	O
end	O
of	O
the	O
volume	O
unassigned	O
,	O
the	O
problem	O
still	O
exist	O
in	O
Server	B-Device
2022	I-Device
.	O
</s>
<s>
That	O
data	O
is	O
still	O
intact	O
and	O
the	O
ReFS	B-Application
partition	O
works	O
normally	O
.	O
</s>
<s>
A	O
solution	O
is	O
to	O
create	O
a	O
new	O
volume	O
and	O
ReFS	B-Application
partition	O
and	O
copy	O
out	O
of	O
the	O
old	O
ReFS	B-Application
and	O
into	O
the	O
new	O
ReFS	B-Application
requiring	O
double	O
storage	O
during	O
the	O
copy	O
before	O
the	O
old	O
volume	O
can	O
be	O
deleted	O
.	O
</s>
<s>
Thin-provisioned	O
volume	O
formatted	O
with	O
ReFS	B-Application
eventually	O
expands	O
the	O
thin	O
volume	O
to	O
the	O
full	O
size	O
of	O
the	O
ReFS	B-Application
formatted	O
size	O
,	O
nullifying	O
the	O
reason	O
to	O
use	O
a	O
thin	O
volume	O
on	O
Windows	O
10	O
.	O
</s>
<s>
When	O
using	O
an	O
NTFS	B-Application
formatted	O
volume	O
on	O
top	O
of	O
a	O
thin	O
volume	O
does	O
not	O
experience	O
the	O
same	O
expansion	O
.	O
</s>
<s>
For	O
example	O
,	O
4TB	O
ReFS	B-Application
two-way	O
mirror	O
99%	O
static	O
data(data logs )	O
1.11	O
TB	O
used	O
,	O
data	O
does	O
not	O
change	O
once	O
added	O
,	O
data	O
added	O
once	O
a	O
month	O
,	O
storage	O
spaces	O
used	O
the	O
entire	O
8TB	O
of	O
storage( should	O
be	O
around	O
2.2	O
TB	O
used	O
in	O
storage	O
spaces	O
)	O
.	O
</s>
<s>
Same	O
storage	O
space	O
different	O
thin	O
volume	O
formatted	O
with	O
ReFS	B-Application
,	O
two-way	O
mirror	O
single	O
data	O
write	O
,	O
but	O
data	O
is	O
used	O
less	O
frequently	O
and	O
added	O
to	O
less	O
frequently	O
257GB	O
of	O
data	O
,	O
storage	O
spaces	O
using	O
7.77TB	O
.	O
</s>
<s>
thin	O
volume	O
NTFS	B-Application
partition	O
,	O
used	O
in	O
the	O
same	O
manner	O
as	O
the	O
257GB	O
partition	O
,	O
but	O
only	O
using	O
601GB	O
.	O
</s>
<s>
Even	O
when	O
Storage	O
Spaces	O
is	O
not	O
thinly	O
provisioned	O
,	O
ReFS	B-Application
may	O
still	O
be	O
unable	O
to	O
dependably	O
correct	O
all	O
file	O
errors	O
in	O
some	O
situations	O
,	O
because	O
Storage	O
Spaces	O
operates	O
on	O
blocks	O
and	O
not	O
files	O
,	O
and	O
therefore	O
some	O
files	O
may	O
potentially	O
lack	O
necessary	O
blocks	O
or	O
recovery	O
data	O
if	O
part	O
of	O
the	O
storage	O
space	O
is	O
not	O
working	O
correctly	O
.	O
</s>
<s>
Windows	B-Application
Store	I-Application
cannot	O
install	O
apps	O
on	O
a	O
ReFS	B-Application
volume	O
.	O
</s>
<s>
At	O
the	O
Storage	O
Developer	O
Conference	O
2015	O
,	O
a	O
Microsoft	O
developer	O
presented	O
enhancements	O
of	O
ReFS	B-Application
expected	O
to	O
be	O
released	O
with	O
Windows	B-Device
Server	I-Device
2016	I-Device
and	O
included	O
in	O
Technical	O
Preview	O
4	O
,	O
titled	O
"	O
ReFS	B-Application
v2	O
"	O
.	O
</s>
<s>
It	O
highlighted	O
that	O
ReFS	B-Application
now	O
included	O
capabilities	O
for	O
very	O
high	O
speed	O
moving	O
,	O
reordering	O
,	O
and	O
cloning	O
of	O
blocks	O
between	O
files	O
(	O
which	O
can	O
be	O
done	O
for	O
all	O
blocks	O
of	O
a	O
file	O
)	O
.	O
</s>
<s>
This	O
is	O
particularly	O
needed	O
for	O
virtualization	B-General_Concept
,	O
and	O
is	O
stated	O
to	O
allow	O
fast	O
provisioning	O
,	O
diff	O
merging	O
,	O
and	O
tiering	O
.	O
</s>
<s>
Other	O
enhancements	O
cover	O
the	O
redo	O
log	O
(	O
for	O
synchronous	O
disk	O
writes	O
)	O
,	O
parallelization	B-Operating_System
,	O
efficient	O
tracking	O
of	O
uninitialized	O
sparse	O
data	O
and	O
files	O
,	O
and	O
efficient	O
4k	O
I/O	B-General_Concept
.	O
</s>
<s>
Windows	B-Device
Server	I-Device
2022	I-Device
(	O
using	O
ReFS	B-Application
version	O
3.7	O
)	O
supports	O
file-level	O
snapshots	O
.	O
</s>
<s>
Windows	O
Insider	O
Preview	O
22H2	O
and	O
23H2	O
(	O
builds	O
226**	O
and	O
25***	O
)	O
support	O
ReFS	B-Application
volume	O
compression	O
using	O
LZ4	B-Language
and	O
zstd	B-Language
algorithms	O
.	O
</s>
<s>
Other	O
operating	O
systems	O
have	O
competing	O
file	B-Application
systems	I-Application
to	O
ReFS	B-Application
,	O
of	O
which	O
the	O
best	O
known	O
are	O
ZFS	B-Application
and	O
Btrfs	B-Operating_System
,	O
in	O
the	O
sense	O
that	O
all	O
three	O
are	O
designed	O
to	O
integrate	O
data	O
protection	O
,	O
snapshots	O
,	O
and	O
silent	O
high-speed	O
background	O
healing	O
of	O
corruption	O
and	O
data	O
errors	O
.	O
</s>
<s>
In	O
2012	O
,	O
Phoronix	O
wrote	O
an	O
analysis	O
of	O
ReFS	B-Application
vs	O
Btrfs	B-Operating_System
,	O
a	O
copy-on-write	B-Language
file	B-Application
system	I-Application
for	O
Linux	B-Application
.	O
</s>
<s>
Their	O
features	O
are	O
similar	O
,	O
with	O
both	O
supporting	O
checksums	O
,	O
RAID-like	O
use	O
of	O
multiple	O
disks	O
,	O
and	O
error	O
detection/correction	O
.	O
</s>
<s>
However	O
,	O
ReFS	B-Application
lacks	O
copy-on-write	B-Language
snapshots	O
and	O
compression	O
,	O
both	O
found	O
in	O
Btrfs	B-Operating_System
and	O
ZFS	B-Application
.	O
</s>
<s>
In	O
2014	O
,	O
a	O
review	O
of	O
ReFS	B-Application
and	O
assessment	O
of	O
its	O
readiness	O
for	O
production	O
use	O
concluded	O
that	O
ReFS	B-Application
had	O
at	O
least	O
some	O
advantages	O
over	O
two	O
of	O
its	O
main	O
file	B-Application
system	I-Application
competitors	O
.	O
</s>
<s>
ZFS	B-Application
(	O
used	O
in	O
Solaris	B-Application
,	O
illumos	B-Application
,	O
FreeBSD	B-Operating_System
and	O
others	O
)	O
was	O
widely	O
criticized	O
for	O
its	O
comparatively	O
extreme	O
memory	O
requirements	O
of	O
many	O
gigabytes	O
of	O
RAM	B-Architecture
for	O
online	O
deduplication	O
.	O
</s>
<s>
However	O
,	O
online	O
deduplication	O
is	O
never	O
enabled	O
by	O
default	O
in	O
ZFS	B-Application
and	O
was	O
not	O
supported	O
at	O
the	O
time	O
by	O
ReFS	B-Application
(	O
it	O
has	O
since	O
been	O
added	O
)	O
,	O
so	O
not	O
enabling	O
ZFS	B-Application
online	O
deduplication	O
yielded	O
a	O
more	O
even	O
comparison	O
between	O
the	O
two	O
file	B-Application
systems	I-Application
as	O
ZFS	B-Application
then	O
has	O
a	O
memory	O
requirement	O
of	O
only	O
a	O
few	O
hundred	O
megabytes	O
.	O
</s>
<s>
Offerings	O
such	O
as	O
Drobo	B-Application
used	O
proprietary	B-Application
methods	O
which	O
have	O
no	O
fallback	O
if	O
the	O
company	O
behind	O
them	O
fails	O
.	O
</s>
<s>
,	O
Microsoft	O
has	O
not	O
published	O
any	O
specifications	O
for	O
ReFS	B-Application
,	O
nor	O
have	O
any	O
working	O
open-source	O
drivers	O
been	O
made	O
.	O
</s>
<s>
A	O
third-party	O
open-source	O
project	O
to	O
document	O
ReFS	B-Application
is	O
on	O
GitHub	B-Application
.	O
</s>
<s>
Paragon	O
Software	O
Group	O
provides	O
a	O
closed-source	B-Application
driver	O
for	O
Windows	O
and	O
Linux	B-Application
.	O
</s>
