<s>
OpenZFS	B-Operating_System
is	O
a	O
free	B-License
and	I-License
open-source	I-License
storage	O
platform	O
licensed	O
under	O
CDDL	B-Application
,	O
that	O
encompasses	O
the	O
functionality	O
of	O
traditional	O
filesystems	B-Application
and	O
logical	B-Application
volume	I-Application
manager	I-Application
.	O
</s>
<s>
It	O
includes	O
protection	O
against	O
data	O
corruption	O
,	O
support	O
for	O
high	O
storage	O
capacities	O
,	O
efficient	O
data	B-General_Concept
compression	I-General_Concept
,	O
snapshots	B-Application
and	O
copy-on-write	B-Language
clones	O
,	O
continuous	O
integrity	O
checking	O
and	O
automatic	O
repair	O
,	O
encryption	O
,	O
remote	O
replication	B-Architecture
with	O
ZFS	B-Application
send	O
and	O
receive	O
,	O
and	O
RAID-Z	O
.	O
</s>
<s>
The	O
OpenZFS	B-Operating_System
project	I-Operating_System
brings	O
together	O
developers	O
from	O
the	O
illumos	B-Application
,	O
Linux	B-Application
,	O
FreeBSD	B-Operating_System
and	O
macOS	B-Application
platforms	O
,	O
and	O
a	O
wide	O
range	O
of	O
companies	O
via	O
the	O
annual	O
OpenZFS	B-Operating_System
Developer	O
Summit	O
.	O
</s>
<s>
Founding	O
members	O
of	O
OpenZFS	B-Operating_System
include	O
Matt	O
Ahrens	O
,	O
one	O
of	O
the	O
main	O
architects	O
of	O
ZFS	B-Application
.	O
</s>
<s>
The	O
OpenZFS	B-Operating_System
project	I-Operating_System
is	O
an	O
open	O
source	O
derivative	O
of	O
the	O
Oracle	B-Application
ZFS	I-Application
project	O
.	O
</s>
<s>
,	O
OpenZFS	B-Operating_System
(	O
on	O
some	O
platforms	O
such	O
as	O
FreeBSD	B-Operating_System
)	O
is	O
gradually	O
being	O
pivoted	O
to	O
be	O
based	O
upon	O
ZFS	B-Application
on	I-Application
Linux	I-Application
,	O
which	O
has	O
developed	O
faster	O
than	O
other	O
variants	O
of	O
OpenZFS	B-Operating_System
and	O
contains	O
new	O
features	O
not	O
yet	O
ported	O
to	O
those	O
other	O
versions	O
.	O
</s>
<s>
The	O
merged	O
code-base	O
will	O
include	O
a	O
number	O
of	O
new	O
features	O
,	O
performance	O
enhancements	O
,	O
and	O
is	O
proposed	O
to	O
be	O
known	O
as	O
OpenZFS	B-Operating_System
2.0	O
.	O
</s>
<s>
The	O
ZFS	B-Application
file	B-Application
system	I-Application
was	O
originally	O
developed	O
by	O
Sun	O
Microsystems	O
for	O
the	O
Solaris	B-Application
operating	I-Application
system	I-Application
.	O
</s>
<s>
The	O
ZFS	B-Application
source	O
code	O
was	O
released	O
in	O
2005	O
under	O
the	O
Common	B-Application
Development	I-Application
and	I-Application
Distribution	I-Application
License	I-Application
(	O
CDDL	B-Application
)	O
as	O
part	O
of	O
the	O
OpenSolaris	B-Operating_System
operating	O
system	O
,	O
and	O
it	O
was	O
later	O
ported	O
to	O
other	O
operating	O
systems	O
and	O
environments	O
.	O
</s>
<s>
The	O
following	O
is	O
a	O
list	O
of	O
key	O
events	O
to	O
the	O
development	O
of	O
ZFS	B-Application
and	O
its	O
various	O
implementations	O
,	O
leading	O
to	O
the	O
creation	O
of	O
OpenZFS	B-Operating_System
as	O
an	O
umbrella	O
project	O
:	O
</s>
<s>
2001	O
:	O
Closed-source	O
development	O
of	O
ZFS	B-Application
started	O
with	O
two	O
engineers	O
at	O
Sun	O
Microsystems	O
.	O
</s>
<s>
2005	O
:	O
ZFS	B-Application
source	O
code	O
was	O
released	O
as	O
part	O
of	O
OpenSolaris	B-Operating_System
.	O
</s>
<s>
2006	O
:	O
Development	O
of	O
a	O
FUSE	B-Application
ZFS	B-Application
port	O
for	O
Linux	B-Application
started	O
.	O
</s>
<s>
2007	O
:	O
Apple	O
started	O
porting	O
of	O
ZFS	B-Application
to	O
Mac	O
OSX	O
.	O
</s>
<s>
2008	O
:	O
A	O
port	O
to	O
FreeBSD	B-Operating_System
was	O
released	O
as	O
part	O
of	O
FreeBSD7.0	O
.	O
</s>
<s>
2008	O
:	O
Development	O
of	O
a	O
native	O
ZFS	B-Application
Linux	B-Application
port	O
started	O
,	O
known	O
as	O
ZFS	B-Application
on	I-Application
Linux	I-Application
.	O
</s>
<s>
2009	O
:	O
Apple	O
's	O
ZFS	B-Application
project	O
closed	O
,	O
and	O
the	O
MacZFS	O
project	O
continued	O
to	O
develop	O
the	O
code	O
.	O
</s>
<s>
2010	O
:	O
OpenSolaris	B-Operating_System
was	O
discontinued	O
,	O
resulting	O
in	O
the	O
further	O
development	O
of	O
ZFS	B-Application
on	O
Solaris	B-Application
being	O
no	O
longer	O
open-source	O
.	O
</s>
<s>
2010	O
:	O
illumos	B-Application
was	O
forked	B-Application
from	O
OpenSolaris	B-Operating_System
as	O
its	O
open-source	O
successor	O
,	O
and	O
continued	O
to	O
develop	O
ZFS	B-Application
in	O
the	O
open	O
.	O
</s>
<s>
Ports	O
of	O
ZFS	B-Application
to	O
other	O
platforms	O
continued	O
pulling	O
in	O
upstream	O
changes	O
from	O
illumos	B-Application
.	O
</s>
<s>
2012	O
:	O
Feature	O
flags	O
were	O
introduced	O
to	O
replace	O
legacy	O
on-disk	O
version	O
numbers	O
,	O
enabling	O
easier	O
distributed	O
evolution	O
of	O
the	O
ZFS	B-Application
on-disk	O
format	O
to	O
support	O
new	O
features	O
.	O
</s>
<s>
2013	O
:	O
Coexisting	O
with	O
the	O
stable	O
version	O
of	O
MacZFS	O
,	O
its	O
prototype	O
generation	O
(	O
known	O
as	O
OpenZFS	B-Operating_System
on	O
OS	O
X	O
or	O
O3X	O
)	O
uses	O
ZFS	B-Application
on	I-Application
Linux	I-Application
as	O
the	O
new	O
upstream	O
codebase	O
.	O
</s>
<s>
2013	O
:	O
The	O
first	O
stable	O
release	O
of	O
ZFS	B-Application
on	I-Application
Linux	I-Application
.	O
</s>
<s>
2013	O
:	O
Official	O
announcement	O
of	O
the	O
OpenZFS	B-Operating_System
as	O
an	O
umbrella	O
project	O
.	O
</s>
<s>
New	O
features	O
and	O
fixes	O
are	O
regularly	O
pulled	O
into	O
OpenZFS	B-Operating_System
from	O
illumos	B-Application
and	O
pushed	O
into	O
all	O
ports	O
to	O
other	O
platforms	O
,	O
and	O
vice	O
versa	O
.	O
</s>
<s>
2016	O
:	O
Ubuntu	B-Operating_System
16.04	O
includes	O
the	O
open-source	O
ZFS	B-Application
file	B-Application
system	I-Application
variant	O
by	O
default	O
.	O
</s>
<s>
As	O
the	O
FSF	B-Operating_System
claimed	O
a	O
CDDL	B-Application
and	O
GPL	B-License
legal	O
incompatibility	O
in	O
2005	O
,	O
Sun	O
's	O
implementation	O
of	O
the	O
ZFS	B-Application
file	B-Application
system	I-Application
was	O
n't	O
used	O
as	O
a	O
basis	O
for	O
the	O
development	O
of	O
a	O
Linux	B-Application
kernel	I-Application
module	I-Application
,	O
it	O
was	O
n't	O
merged	O
into	O
the	O
Linux	B-Operating_System
kernel	I-Operating_System
mainline	O
,	O
and	O
Linux	B-Application
distributions	I-Application
did	O
not	O
include	O
it	O
as	O
a	O
precompiled	O
kernel	B-Application
module	I-Application
.	O
</s>
<s>
As	O
a	O
workaround	O
,	O
FUSE	B-Application
,	O
a	O
framework	O
that	O
allows	O
file	B-Application
systems	I-Application
to	O
run	O
in	O
userspace	B-Operating_System
,	O
was	O
used	O
on	O
Linux	B-Application
as	O
a	O
separation	O
layer	O
for	O
which	O
the	O
licensing	O
issues	O
are	O
not	O
in	O
effect	O
,	O
although	O
with	O
a	O
set	O
of	O
its	O
own	O
issues	O
that	O
include	O
performance	O
penalty	O
.	O
</s>
<s>
However	O
,	O
the	O
April	O
2016	O
release	O
of	O
Ubuntu	B-Operating_System
16.04LTS	O
includes	O
CDDL-licensed	O
ZFS	B-Application
on	I-Application
Linux	I-Application
as	O
a	O
kernel	B-Application
module	I-Application
that	O
is	O
maintained	O
as	O
a	O
separate	O
project	O
,	O
outside	O
the	O
Linux	B-Operating_System
kernel	I-Operating_System
mainline	O
,	O
claiming	O
license	O
compatibility	O
.	O
</s>
<s>
In	O
the	O
release	O
version	O
of	O
Mac	B-Application
OS	I-Application
X	I-Application
10.5	O
,	O
ZFS	B-Application
was	O
available	O
in	O
read-only	O
mode	O
from	O
the	O
command	O
line	O
,	O
which	O
lacks	O
the	O
possibility	O
to	O
create	O
zpools	O
or	O
write	O
to	O
them	O
.	O
</s>
<s>
Before	O
the	O
10.5	O
release	O
,	O
Apple	O
released	O
the	O
"	O
ZFS	B-Application
Beta	O
Seed	O
v1.1	O
"	O
,	O
which	O
allowed	O
read-write	O
access	O
and	O
the	O
creation	O
of	O
zpools	O
;	O
however	O
,	O
the	O
installer	O
for	O
the	O
"	O
ZFS	B-Application
Beta	O
Seed	O
v1.1	O
"	O
has	O
been	O
reported	O
to	O
only	O
work	O
on	O
version	O
10.5.0	O
,	O
and	O
has	O
not	O
been	O
updated	O
for	O
version	O
10.5.1	O
and	O
above	O
.	O
</s>
<s>
In	O
August	O
2007	O
,	O
Apple	O
opened	O
a	O
ZFS	B-Application
project	O
on	O
their	O
Mac	B-Application
OS	I-Application
Forge	O
web	O
site	O
.	O
</s>
<s>
On	O
that	O
site	O
,	O
Apple	O
provided	O
the	O
source	O
code	O
and	O
binaries	O
of	O
their	O
port	O
of	O
ZFS	B-Application
which	O
includes	O
read-write	O
access	O
,	O
but	O
there	O
was	O
no	O
installer	O
available	O
until	O
a	O
third-party	O
developer	O
created	O
one	O
.	O
</s>
<s>
In	O
October	O
2009	O
,	O
Apple	O
announced	O
a	O
shutdown	O
of	O
the	O
ZFS	B-Application
project	O
on	O
Mac	B-Application
OS	I-Application
Forge	O
.	O
</s>
<s>
That	O
is	O
to	O
say	O
that	O
their	O
own	O
hosting	O
and	O
involvement	O
in	O
ZFS	B-Application
was	O
summarily	O
discontinued	O
.	O
</s>
<s>
Apple	O
eventually	O
released	O
the	O
legally	O
required	O
,	O
CDDL-derived	O
,	O
portion	O
of	O
the	O
source	O
code	O
of	O
their	O
final	O
public	O
beta	O
of	O
ZFS	B-Application
,	O
code	O
named	O
"	O
10a286	O
"	O
.	O
</s>
<s>
Complete	O
ZFS	B-Application
support	O
was	O
once	O
advertised	O
as	O
a	O
feature	O
of	O
Snow	O
Leopard	O
Server	O
(	O
Mac	B-Operating_System
OS	I-Operating_System
X	I-Operating_System
Server	I-Operating_System
10.6	O
)	O
.	O
</s>
<s>
As	O
of	O
July	O
2012	O
,	O
MacZFS	O
implements	O
zpool	O
version	O
8	O
and	O
ZFS	B-Application
version	O
2	O
,	O
from	O
the	O
October	O
2008	O
release	O
of	O
Solaris	B-Application
.	O
</s>
<s>
OpenSolaris	B-Operating_System
2008.05	I-Operating_System
,	O
2008.11	O
and	O
2009.06	O
use	O
ZFS	B-Application
as	O
their	O
default	O
filesystem	B-Application
.	O
</s>
<s>
OpenIndiana	B-Application
uses	O
OpenZFS	B-Operating_System
with	O
feature	O
flags	O
as	O
implemented	O
in	O
Illumos	B-Application
.	O
</s>
<s>
ZFS	B-Application
version	O
28	O
used	O
up	O
to	O
version	O
151a3	O
.	O
</s>
<s>
By	O
upgrading	O
from	O
OpenSolaris	B-Operating_System
snv_134	O
to	O
both	O
OpenIndiana	B-Application
and	O
Solaris	B-Application
11	I-Application
Express	O
,	O
one	O
also	O
has	O
the	O
ability	O
to	O
upgrade	O
and	O
separately	O
boot	O
Solaris	B-Application
11	I-Application
Express	O
on	O
the	O
same	O
ZFS	B-Application
pool	O
.	O
</s>
<s>
OpenZFS	B-Operating_System
on	O
OSX	O
(	O
abbreviated	O
to	O
O3X	O
)	O
is	O
an	O
implementation	O
of	O
ZFS	B-Application
for	O
macOS	B-Application
.	O
</s>
<s>
O3X	O
is	O
under	O
active	O
development	O
,	O
with	O
close	O
relation	O
to	O
ZFS	B-Application
on	I-Application
Linux	I-Application
and	O
illumos	B-Application
 '	O
ZFS	B-Application
implementation	O
,	O
while	O
maintaining	O
feature	O
flag	O
compatibility	O
with	O
ZFS	B-Application
on	I-Application
Linux	I-Application
.	O
</s>
<s>
O3X	O
implements	O
zpool	O
version	O
5000	O
,	O
and	O
includes	O
the	O
Solaris	B-Application
Porting	O
Layer	O
(	O
SPL	O
)	O
originally	O
written	O
for	O
MacZFS	O
,	O
which	O
has	O
been	O
further	O
enhanced	O
to	O
include	O
a	O
memory	O
management	O
layer	O
based	O
on	O
the	O
illumos	B-Application
kmem	O
and	O
vmem	O
allocators	O
.	O
</s>
<s>
O3X	O
is	O
fully	O
featured	O
,	O
supporting	O
LZ4	O
compression	O
,	O
deduplication	O
,	O
ARC	O
,	O
L2ARC	B-Application
,	O
and	O
SLOG	O
.	O
</s>
<s>
MacZFS	O
is	O
free	O
software	O
providing	O
support	O
for	O
ZFS	B-Application
on	O
macOS	B-Application
.	O
</s>
<s>
The	O
stable	O
legacy	O
branch	O
provides	O
up	O
to	O
ZFS	B-Application
pool	O
version	O
8	O
and	O
ZFS	B-Application
filesystem	B-Application
version	O
2	O
.	O
</s>
<s>
The	O
development	O
branch	O
,	O
based	O
on	O
ZFS	B-Application
on	I-Application
Linux	I-Application
and	O
OpenZFS	B-Operating_System
,	O
provides	O
updated	O
ZFS	B-Application
functionality	O
,	O
such	O
as	O
up	O
to	O
ZFS	B-Application
zpool	O
version	O
5000	O
and	O
feature	O
flags	O
.	O
</s>
<s>
A	O
proprietary	O
implementation	O
of	O
ZFS	B-Application
(	O
Zevo	O
)	O
was	O
available	O
at	O
no	O
cost	O
from	O
GreenBytes	O
,	O
Inc.	O
,	O
implementing	O
up	O
to	O
ZFS	B-Application
file	B-Application
system	I-Application
version	O
5	O
and	O
ZFS	B-Application
pool	O
version	O
28	O
.	O
</s>
<s>
Zevo	O
offered	O
a	O
limited	O
ZFS	B-Application
feature	O
set	O
,	O
pending	O
further	O
commercial	O
development	O
;	O
it	O
was	O
sold	O
to	O
Oracle	B-Application
in	O
2014	O
,	O
with	O
unknown	O
future	O
plans	O
.	O
</s>
<s>
Edward	O
O'Callaghan	O
started	O
the	O
initial	O
port	O
of	O
ZFS	B-Application
to	O
DragonFlyBSD	B-Application
.	O
</s>
<s>
The	O
NetBSD	B-Device
ZFS	B-Application
port	O
was	O
started	O
as	O
a	O
part	O
of	O
the	O
2007	O
Google	B-Application
Summer	I-Application
of	I-Application
Code	I-Application
and	O
in	O
August	O
2009	O
,	O
the	O
code	O
was	O
merged	O
into	O
NetBSD	B-Device
's	O
source	O
tree	O
.	O
</s>
<s>
Paweł	O
Jakub	O
Dawidek	O
ported	O
ZFS	B-Application
to	O
FreeBSD	B-Operating_System
,	O
and	O
it	O
has	O
been	O
part	O
of	O
FreeBSD	B-Operating_System
since	O
version	O
7.0	O
.	O
</s>
<s>
This	O
includes	O
zfsboot	O
,	O
which	O
allows	O
booting	O
FreeBSD	B-Operating_System
directly	O
from	O
a	O
ZFS	B-Application
dataset	O
.	O
</s>
<s>
FreeBSD	B-Operating_System
's	O
ZFS	B-Application
implementation	O
is	O
fully	O
functional	O
;	O
the	O
only	O
missing	O
features	O
are	O
kernel	B-Operating_System
CIFS	B-Operating_System
server	O
and	O
iSCSI	B-Protocol
,	O
but	O
the	O
latter	O
can	O
be	O
added	O
using	O
externally	O
available	O
packages	O
.	O
</s>
<s>
Samba	B-Language
can	O
be	O
used	O
to	O
provide	O
a	O
userspace	B-Operating_System
CIFS	B-Operating_System
server	O
.	O
</s>
<s>
FreeBSD	B-Operating_System
13.0-RELEASE	O
switches	O
ZFS	B-Application
implementation	O
from	O
illumos-based	O
code	O
base	O
to	O
the	O
unified	O
OpenZFS	B-Operating_System
2	O
code	O
base	O
.	O
</s>
<s>
This	O
change	O
allows	O
FreeBSD	B-Operating_System
to	O
receive	O
OpenZFS	B-Operating_System
improvements	O
much	O
quicker	O
.	O
</s>
<s>
MidnightBSD	B-Application
,	O
a	O
desktop	O
operating	O
system	O
derived	O
from	O
FreeBSD	B-Operating_System
,	O
supports	O
ZFS	B-Application
storage	O
pool	O
version	O
6	O
as	O
of	O
0.3-RELEASE	O
.	O
</s>
<s>
This	O
was	O
derived	O
from	O
code	O
included	O
in	O
FreeBSD	B-Operating_System
7.0-RELEASE	O
.	O
</s>
<s>
An	O
update	O
to	O
storage	O
pool	O
28	O
is	O
in	O
progress	O
in	O
0.4-CURRENT	O
and	O
based	O
on	O
9-STABLE	O
sources	O
around	O
FreeBSD	B-Operating_System
9.1-RELEASE	O
code	O
.	O
</s>
<s>
TrueOS	B-Application
(	O
formerly	O
known	O
as	O
PC-BSD	B-Application
,	O
now	O
defunct	O
)	O
was	O
a	O
desktop-oriented	O
distribution	O
of	O
FreeBSD	B-Operating_System
,	O
which	O
inherited	O
its	O
ZFS	B-Application
support	O
.	O
</s>
<s>
TrueNAS	B-Application
Core	O
,	O
an	O
embedded	O
open	O
source	O
network-attached	B-Application
storage	I-Application
(	O
NAS	B-Application
)	O
distribution	O
based	O
on	O
FreeBSD	B-Operating_System
,	O
has	O
the	O
same	O
ZFS	B-Application
support	O
as	O
FreeBSD	B-Operating_System
and	O
PC-BSD	B-Application
.	O
</s>
<s>
pfSense	B-Protocol
,	O
an	O
open	O
source	O
BSD	O
based	O
router	B-Protocol
,	O
supports	O
ZFS	B-Application
,	O
including	O
installation	O
and	O
booting	O
to	O
ZFS	B-Application
pools	O
,	O
as	O
of	O
version	O
2.4	O
.	O
</s>
<s>
XigmaNAS	B-Application
(	O
formerly	O
NAS4Free	B-Application
)	O
,	O
an	O
embedded	O
open	O
source	O
network-attached	B-Application
storage	I-Application
(	O
NAS	B-Application
)	O
distribution	O
based	O
on	O
FreeBSD	B-Operating_System
,	O
has	O
the	O
same	O
ZFS	B-Application
support	O
as	O
FreeBSD	B-Operating_System
,	O
ZFS	B-Application
storage	O
pool	O
version	O
5000	O
.	O
</s>
<s>
This	O
project	O
is	O
a	O
continuation	O
of	O
FreeNAS	B-Application
7	O
series	O
project	O
.	O
</s>
<s>
Being	O
based	O
on	O
the	O
FreeBSD	B-Operating_System
kernel	B-Operating_System
,	O
Debian	O
GNU/kFreeBSD	O
has	O
ZFS	B-Application
support	O
from	O
the	O
kernel	B-Operating_System
.	O
</s>
<s>
However	O
,	O
additional	O
userland	O
tools	O
are	O
required	O
,	O
while	O
it	O
is	O
possible	O
to	O
have	O
ZFS	B-Application
as	O
root	O
or	O
/boot	O
file	B-Application
system	I-Application
in	O
which	O
case	O
required	O
GRUB	B-Application
configuration	O
is	O
performed	O
by	O
the	O
Debian	O
installer	O
since	O
the	O
Wheezy	O
release	O
.	O
</s>
<s>
Although	O
the	O
ZFS	B-Application
filesystem	B-Application
supports	O
Linux-based	B-Application
operating	I-Application
systems	I-Application
,	O
difficulties	O
arise	O
for	O
Linux	B-Application
distribution	I-Application
maintainers	O
wishing	O
to	O
provide	O
native	O
support	O
for	O
ZFS	B-Application
in	O
their	O
products	O
due	O
to	O
potential	O
legal	O
incompatibilities	O
between	O
the	O
CDDL	B-Application
license	O
used	O
by	O
the	O
ZFS	B-Application
code	O
,	O
and	O
the	O
GPL	B-License
license	I-License
used	O
by	O
the	O
Linux	B-Operating_System
kernel	I-Operating_System
.	O
</s>
<s>
To	O
enable	O
ZFS	B-Application
support	O
within	O
Linux	B-Application
,	O
a	O
loadable	B-Application
kernel	I-Application
module	I-Application
containing	O
the	O
CDDL-licensed	O
ZFS	B-Application
code	O
must	O
be	O
compiled	O
and	O
loaded	O
into	O
the	O
kernel	B-Operating_System
.	O
</s>
<s>
According	O
to	O
the	B-Operating_System
Free	I-Operating_System
Software	I-Operating_System
Foundation	I-Operating_System
,	O
the	O
wording	O
of	O
the	O
GPL	B-License
license	I-License
legally	O
prohibits	O
redistribution	O
of	O
the	O
resulting	O
product	O
as	O
a	O
derivative	O
work	O
,	O
though	O
this	O
viewpoint	O
has	O
caused	O
some	O
controversy	O
.	O
</s>
<s>
One	O
potential	O
workaround	O
to	O
licensing	O
incompatibility	O
was	O
trialed	O
in	O
2006	O
,	O
with	O
an	O
experimental	O
port	O
of	O
the	O
ZFS	B-Application
code	O
to	O
Linux	B-Application
's	O
FUSE	B-Application
system	O
.	O
</s>
<s>
The	O
filesystem	B-Application
ran	O
entirely	O
in	O
userspace	B-Operating_System
instead	O
of	O
being	O
integrated	O
into	O
the	O
Linux	B-Operating_System
kernel	I-Operating_System
,	O
and	O
was	O
therefore	O
not	O
considered	O
a	O
derivative	O
work	O
of	O
the	O
kernel	B-Operating_System
.	O
</s>
<s>
This	O
approach	O
was	O
functional	O
,	O
but	O
suffered	O
from	O
significant	O
performance	O
penalties	O
when	O
compared	O
with	O
integrating	O
the	O
filesystem	B-Application
as	O
a	O
native	O
kernel	B-Application
module	I-Application
running	O
in	O
kernel	B-Operating_System
space	I-Operating_System
.	O
</s>
<s>
As	O
of	O
2016	O
,	O
the	O
ZFS	B-Application
on	O
FUSE	B-Application
project	O
appears	O
to	O
be	O
defunct	O
.	O
</s>
<s>
A	O
native	O
port	O
of	O
ZFS	B-Application
for	O
Linux	B-Application
produced	O
by	O
the	O
Lawrence	O
Livermore	O
National	O
Laboratory	O
(	O
LLNL	O
)	O
was	O
released	O
in	O
March	O
2013	O
,	O
following	O
these	O
key	O
events	O
:	O
</s>
<s>
,	O
ZFS	B-Application
on	I-Application
Linux	I-Application
uses	O
the	O
OpenZFS	B-Operating_System
pool	O
version	O
number	O
5000	O
,	O
which	O
indicates	O
that	O
the	O
features	O
it	O
supports	O
are	O
defined	O
via	O
feature	O
flags	O
.	O
</s>
<s>
This	O
pool	O
version	O
is	O
an	O
unchanging	O
number	O
that	O
is	O
expected	O
to	O
never	O
conflict	O
with	O
version	O
numbers	O
given	O
by	O
Oracle	B-Application
.	O
</s>
<s>
Another	O
native	O
port	O
for	O
Linux	B-Application
was	O
developed	O
by	O
KQ	O
InfoTech	O
in	O
2010	O
.	O
</s>
<s>
In	O
April	O
2011	O
,	O
KQ	O
Infotech	O
was	O
acquired	O
by	O
sTec	O
,	O
Inc.	O
,	O
and	O
their	O
work	O
on	O
ZFS	B-Application
ceased	O
.	O
</s>
<s>
Source	O
code	O
of	O
this	O
port	O
can	O
be	O
found	O
on	O
GitHub	B-Application
.	O
</s>
<s>
The	O
work	O
of	O
KQ	O
InfoTech	O
was	O
ultimately	O
integrated	O
into	O
the	O
LLNL	O
's	O
native	O
port	O
of	O
ZFS	B-Application
for	O
Linux	B-Application
.	O
</s>
<s>
While	O
the	O
license	O
incompatibility	O
may	O
arise	O
with	O
the	O
distribution	O
of	O
compiled	O
binaries	O
containing	O
ZFS	B-Application
code	O
,	O
it	O
is	O
generally	O
agreed	O
that	O
distribution	O
of	O
the	O
source	O
code	O
itself	O
is	O
not	O
affected	O
by	O
this	O
.	O
</s>
<s>
In	O
Gentoo	B-Application
,	O
configuring	O
a	O
ZFS	B-Application
root	O
filesystem	B-Application
is	O
well	O
documented	O
and	O
the	O
required	O
packages	O
can	O
be	O
installed	O
from	O
its	O
package	O
repository	O
.	O
</s>
<s>
Slackware	B-Application
also	O
provides	O
documentation	O
on	O
supporting	O
ZFS	B-Application
,	O
both	O
as	O
a	O
kernel	B-Application
module	I-Application
and	O
when	O
built	O
into	O
the	O
kernel	B-Operating_System
.	O
</s>
<s>
The	O
question	O
of	O
the	O
CDDL	B-Application
license	O
's	O
compatibility	O
with	O
the	O
GPL	B-License
license	I-License
resurfaced	O
in	O
2015	O
,	O
when	O
the	O
Linux	B-Application
distribution	I-Application
Ubuntu	B-Operating_System
announced	O
that	O
it	O
intended	O
to	O
make	O
precompiled	O
OpenZFS	B-Operating_System
binary	O
kernel	B-Application
modules	I-Application
available	O
to	O
end-users	O
directly	O
from	O
the	O
distribution	O
's	O
official	O
package	O
repositories	O
.	O
</s>
<s>
In	O
2016	O
,	O
Ubuntu	B-Operating_System
announced	O
that	O
a	O
legal	O
review	O
resulted	O
in	O
the	O
conclusion	O
that	O
providing	O
support	O
for	O
ZFS	B-Application
via	O
a	O
binary	O
kernel	B-Application
module	I-Application
was	O
not	O
in	O
violation	O
of	O
the	O
provisions	O
of	O
the	O
GPL	B-License
license	I-License
.	O
</s>
<s>
Others	O
,	O
such	O
as	O
the	O
Software	O
Freedom	O
Law	O
Center	O
followed	O
Ubuntu	B-Operating_System
's	O
conclusion	O
,	O
while	O
the	O
FSF	B-Operating_System
and	O
SFC	O
reiterated	O
their	O
opposing	O
view	O
.	O
</s>
<s>
Ubuntu	B-Operating_System
16.04	O
LTS	O
(	O
"	O
Xenial	O
Xerus	O
"	O
)	O
,	O
released	O
on	O
April	O
21	O
,	O
2016	O
,	O
allows	O
the	O
user	O
to	O
install	O
the	O
OpenZFS	B-Operating_System
binary	O
packages	O
directly	O
from	O
the	O
Ubuntu	B-Operating_System
software	O
repositories	O
.	O
</s>
<s>
As	O
of	O
2019	O
,	O
Ubuntu	B-Operating_System
supports	O
experimental	O
installation	O
of	O
ZFS	B-Application
as	O
a	O
root	O
filesystem	B-Application
,	O
starting	O
with	O
the	O
19.10	O
release	O
(	O
"	O
Eoan	O
Ermine	O
"	O
)	O
,	O
to	O
support	O
coexistence	O
of	O
a	O
nearly	O
pure	O
ZFS	B-Application
OS	O
with	O
GRUB	B-Application
and	O
other	O
operating	O
systems	O
on	O
the	O
same	O
disk	O
.	O
</s>
<s>
A	O
version	O
of	O
TrueNAS	B-Application
by	O
iXsystems	O
,	O
but	O
based	O
on	O
Debian	O
Linux	B-Application
still	O
uses	O
OpenZFS	B-Operating_System
for	O
main	O
storage	O
but	O
adds	O
some	O
container	O
support	O
via	O
Kubernetes	O
&	O
Docker	O
.	O
</s>
<s>
Furthermore	O
,	O
it	O
will	O
allow	O
clustered	O
Docker	O
and	O
ZFS	B-Application
via	O
gluster	O
.	O
</s>
<s>
A	O
port	O
of	O
open	O
source	O
ZFS	B-Application
was	O
attempted	O
in	O
2010	O
but	O
after	O
a	O
hiatus	O
of	O
over	O
one	O
year	O
development	O
ceased	O
in	O
2012	O
.	O
</s>
<s>
In	O
October	O
2017	O
a	O
new	O
port	O
of	O
OpenZFS	B-Operating_System
was	O
announced	O
by	O
Jörgen	O
Lundman	O
at	O
OpenZFS	B-Operating_System
Developer	O
Summit	O
.	O
</s>
<s>
2010	O
:	O
illumos	B-Application
founded	O
as	O
an	O
open	O
source	O
successor	O
,	O
and	O
continued	O
to	O
develop	O
ZFS	B-Application
in	O
the	O
open	O
.	O
</s>
<s>
Ports	O
of	O
ZFS	B-Application
to	O
other	O
platforms	O
continued	O
porting	O
upstream	O
changes	O
from	O
illumos	B-Application
.	O
</s>
<s>
2013	O
:	O
OpenZFS	B-Operating_System
project	I-Operating_System
founded	O
,	O
aiming	O
at	O
coordinated	O
open-source	O
development	O
of	O
ZFS	B-Application
.	O
</s>
<s>
The	O
OpenZFS	B-Operating_System
project	I-Operating_System
provides	O
a	O
common	O
foundation	O
for	O
any	O
interested	O
groups	O
and	O
organizations	O
to	O
contribute	O
and	O
collaborate	O
towards	O
a	O
common	O
open	O
source	O
ZFS	B-Application
core	O
,	O
and	O
in	O
addition	O
,	O
to	O
also	O
maintain	O
any	O
specific	O
code	O
and	O
validation	O
processes	O
needed	O
for	O
core	O
ZFS	B-Application
code	O
to	O
work	O
with	O
their	O
own	O
individual	O
systems	O
.	O
</s>
<s>
The	O
following	O
is	O
a	O
list	O
of	O
open-source	O
ZFS	B-Application
ports	O
and	O
forks	B-Application
:	O
</s>
<s>
2006	O
:	O
Development	O
of	O
a	O
FUSE	B-Application
port	O
for	O
Linux	B-Application
started	O
.	O
</s>
<s>
2007	O
:	O
Apple	O
started	O
porting	O
ZFS	B-Application
to	O
Mac	B-Application
OS	I-Application
X	I-Application
.	O
</s>
<s>
2008	O
:	O
A	O
port	O
to	O
FreeBSD	B-Operating_System
was	O
released	O
as	O
part	O
of	O
FreeBSD	B-Operating_System
7.0	O
.	O
</s>
<s>
2008	O
:	O
Development	O
of	O
a	O
native	O
Linux	B-Application
port	O
started	O
.	O
</s>
<s>
2009	O
:	O
Apple	O
's	O
ZFS	B-Application
project	O
closed	O
.	O
</s>
<s>
With	O
ZFS	B-Application
in	O
Oracle	B-Application
Solaris	I-Application
:	O
as	O
new	O
features	O
are	O
introduced	O
,	O
the	O
version	O
numbers	O
of	O
the	O
pool	O
and	O
file	B-Application
system	I-Application
are	O
incremented	O
to	O
designate	O
the	O
format	O
and	O
features	O
available	O
.	O
</s>
<s>
Features	O
that	O
are	O
available	O
in	O
specific	O
file	B-Application
system	I-Application
versions	O
require	O
a	O
specific	O
pool	O
version	O
.	O
</s>
<s>
Distributed	B-Application
development	I-Application
of	O
OpenZFS	B-Operating_System
involves	O
feature	O
flags	O
and	O
pool	O
version	O
5000	O
,	O
an	O
unchanging	O
number	O
that	O
is	O
expected	O
to	O
never	O
conflict	O
with	O
version	O
numbers	O
given	O
by	O
Oracle	B-Application
.	O
</s>
<s>
Illumos	B-Application
uses	O
pool	O
version	O
5000	O
for	O
this	O
purpose	O
.	O
</s>
<s>
Originally	O
,	O
version	O
numbers	O
of	O
the	O
pool	O
and	O
file	B-Application
system	I-Application
were	O
incremented	O
as	O
new	O
features	O
were	O
introduced	O
,	O
in	O
order	O
to	O
designate	O
the	O
on-disk	O
file	B-Application
system	I-Application
format	O
and	O
available	O
features	O
.	O
</s>
<s>
This	O
worked	O
well	O
when	O
a	O
single	O
entity	O
controlled	O
the	O
development	O
of	O
ZFS	B-Application
,	O
and	O
this	O
versioning	O
scheme	O
is	O
still	O
in	O
use	O
with	O
the	O
ZFS	B-Application
in	O
Oracle	B-Application
Solaris	I-Application
.	O
</s>
<s>
In	O
a	O
more	O
distributed	B-Application
development	I-Application
model	O
,	O
having	O
a	O
single	O
version	O
number	O
is	O
far	O
from	O
ideal	O
as	O
all	O
implementations	O
of	O
OpenZFS	B-Operating_System
would	O
need	O
to	O
agree	O
on	O
all	O
changes	O
to	O
the	O
on-disk	O
file	O
system	O
format	O
.	O
</s>
<s>
The	O
solution	O
selected	O
by	O
OpenZFS	B-Operating_System
was	O
to	O
introduce	O
feature	O
flags	O
as	O
a	O
new	O
versioning	O
system	O
that	O
tags	O
on-disk	O
format	O
changes	O
with	O
unique	O
names	O
,	O
and	O
supports	O
both	O
completely	O
independent	O
format	O
changes	O
and	O
format	O
changes	O
that	O
depend	O
on	O
each	O
other	O
.	O
</s>
<s>
A	O
pool	O
can	O
be	O
moved	O
and	O
used	O
between	O
OpenZFS	B-Operating_System
implementations	O
as	O
long	O
as	O
all	O
feature	O
flags	O
in	O
use	O
by	O
the	O
pool	O
are	O
supported	O
by	O
both	O
implementations	O
.	O
</s>
<s>
In	O
OpenZFS	B-Operating_System
,	O
the	O
pool	O
version	O
is	O
permanently	O
set	O
to	O
5000	O
,	O
signifying	O
that	O
the	O
pool	O
indicates	O
new	O
features	O
by	O
setting	O
or	O
unsetting	O
ZFS	B-Application
feature	O
flags	O
rather	O
than	O
by	O
incrementing	O
the	O
pool	O
version	O
.	O
</s>
<s>
The	O
number	O
5000	O
was	O
chosen	O
because	O
it	O
is	O
expected	O
to	O
never	O
conflict	O
with	O
version	O
numbers	O
given	O
by	O
Oracle	B-Application
.	O
</s>
<s>
Disabled	O
features	O
are	O
those	O
that	O
will	O
not	O
be	O
used	O
,	O
and	O
no	O
on-disk	O
format	O
changes	O
will	O
be	O
made	O
;	O
as	O
a	O
result	O
,	O
such	O
features	O
are	O
backward-compatible	B-General_Concept
.	O
</s>
<s>
Enabled	O
features	O
are	O
those	O
that	O
will	O
be	O
used	O
,	O
no	O
on-disk	O
format	O
changes	O
have	O
been	O
made	O
yet	O
,	O
but	O
the	O
software	O
may	O
make	O
the	O
changes	O
at	O
any	O
time	O
;	O
such	O
features	O
are	O
still	O
backward-compatible	B-General_Concept
.	O
</s>
<s>
Active	O
features	O
are	O
those	O
that	O
have	O
made	O
backward-incompatible	B-General_Concept
on-disk	O
format	O
changes	O
to	O
the	O
pool	O
.	O
</s>
<s>
In	O
general	O
,	O
state	O
of	O
a	O
feature	O
can	O
be	O
changed	O
from	O
active	O
back	O
to	O
enabled	O
,	O
undoing	O
that	O
way	O
performed	O
on-disk	O
format	O
changes	O
and	O
making	O
the	O
pool	O
compatible	O
again	O
with	O
an	O
older	O
OpenZFS	B-Operating_System
implementation	O
;	O
however	O
,	O
for	O
some	O
features	O
that	O
might	O
not	O
be	O
possible	O
.	O
</s>
<s>
The	O
former	O
are	O
the	O
features	O
that	O
an	O
OpenZFS	B-Operating_System
implementation	O
must	O
support	O
to	O
be	O
capable	O
of	O
writing	O
to	O
the	O
pool	O
,	O
while	O
supporting	O
such	O
features	O
is	O
not	O
mandatory	O
for	O
opening	O
the	O
pool	O
in	O
read-only	O
mode	O
.	O
</s>
<s>
The	O
latter	O
are	O
the	O
features	O
that	O
an	O
OpenZFS	B-Operating_System
implementation	O
must	O
support	O
to	O
be	O
able	O
to	O
read	O
from	O
the	O
pool	O
or	O
to	O
just	O
open	O
it	O
,	O
because	O
opening	O
a	O
pool	O
is	O
not	O
possible	O
without	O
actually	O
reading	O
from	O
it	O
.	O
</s>
<s>
For	O
example	O
,	O
feature	O
adds	O
a	O
new	O
on-disk	O
data	O
structure	O
to	O
keep	O
track	O
of	O
freed	O
datasets	O
,	O
but	O
an	O
OpenZFS	B-Operating_System
implementation	O
does	O
not	O
need	O
to	O
know	O
about	O
this	O
data	O
structure	O
to	O
access	O
the	O
pool	O
in	O
read-only	O
mode	O
.	O
</s>
<s>
Additionally	O
,	O
writing	O
to	O
a	O
pool	O
that	O
has	O
some	O
features	O
in	O
active	O
state	O
is	O
not	O
possible	O
by	O
an	O
OpenZFS	B-Operating_System
implementation	O
that	O
does	O
not	O
support	O
the	O
same	O
features	O
.	O
</s>
<s>
Historically	O
,	O
OpenZFS	B-Operating_System
has	O
been	O
implemented	O
as	O
a	O
core	O
ZFS	B-Application
code	O
,	O
with	O
each	O
operating	O
system	O
's	O
team	O
adapting	O
it	O
to	O
fit	O
into	O
their	O
projects	O
.	O
</s>
<s>
Over	O
time	O
,	O
new	O
feature	O
development	O
shifted	O
from	O
Illumos	B-Application
to	O
Linux	B-Application
.	O
</s>
<s>
These	O
new	O
features	O
and	O
fixes	O
then	O
had	O
to	O
be	O
backported	O
to	O
Illumos	B-Application
before	O
they	O
could	O
be	O
re-ported	O
for	O
FreeBSD	B-Operating_System
.	O
</s>
<s>
But	O
this	O
was	O
difficult	O
because	O
the	O
Linux	B-Application
version	O
also	O
included	O
many	O
smaller	O
changes	O
,	O
which	O
were	O
hard	O
to	O
disentangle	O
.	O
</s>
<s>
In	O
2018	O
,	O
it	O
was	O
agreed	O
that	O
OpenZFS	B-Operating_System
development	O
would	O
be	O
overhauled	O
to	O
remedy	O
these	O
issues	O
.	O
</s>
<s>
Rather	O
than	O
try	O
to	O
import	O
all	O
the	O
Linux	B-Application
changes	O
to	O
other	O
platforms	O
piecemeal	O
,	O
the	O
entire	O
Linux	B-Application
ZFS	B-Application
code	O
would	O
be	O
'	O
pivoted	O
 '	O
as	O
a	O
whole	O
,	O
with	O
other	O
platforms	O
being	O
based	O
on	O
the	O
more	O
actively	O
developed	O
Linux	B-Application
version	O
.	O
</s>
<s>
The	O
plans	O
included	O
appropriate	O
porting	O
layers	O
to	O
prevent	O
Linux	B-Application
,	O
GPL	B-License
or	O
Linux-KPI	O
shim	B-General_Concept
code	O
from	O
being	O
introduced	O
to	O
other	O
platform	O
kernels	B-Operating_System
.	O
</s>
<s>
The	O
features	O
in	O
progress	O
or	O
ported	O
for	O
OpenZFS	B-Operating_System
2.0	O
is	O
lengthy	O
,	O
and	O
includes	O
:	O
</s>
