<s>
HAMMER2	B-Application
is	O
a	O
successor	O
to	O
the	O
HAMMER	B-Application
filesystem	O
,	O
redesigned	O
from	O
the	O
ground	O
up	O
to	O
support	O
enhanced	O
clustering	B-Architecture
.	O
</s>
<s>
HAMMER2	B-Application
supports	O
online	O
and	O
batched	O
deduplication	B-General_Concept
,	O
snapshots	B-Application
,	O
directory	O
entry	O
indexing	O
,	O
multiple	O
mountable	O
filesystem	B-Application
roots	I-Application
,	O
mountable	O
snapshots	B-Application
,	O
a	O
low	O
memory	O
footprint	O
,	O
compression	B-General_Concept
,	O
encryption	B-Application
,	O
zero-detection	O
,	O
data	O
and	O
metadata	O
checksumming	O
,	O
and	O
synchronization	O
to	O
other	O
filesystems	O
or	O
nodes	O
.	O
</s>
<s>
The	O
HAMMER2	B-Application
file	O
system	O
was	O
conceived	O
by	O
Matthew	O
Dillon	O
,	O
who	O
initially	O
planned	O
to	O
bring	O
it	O
up	O
to	O
minimal	O
working	O
state	O
by	O
July	O
2012	O
and	O
ship	O
the	O
final	O
version	O
in	O
2013	O
.	O
</s>
<s>
During	O
Google	B-Application
Summer	I-Application
of	I-Application
Code	I-Application
2013	I-Application
Daniel	O
Flores	O
implemented	O
compression	B-General_Concept
in	O
HAMMER2	B-Application
using	O
LZ4	B-Language
and	O
zlib	B-Language
algorithms	O
.	O
</s>
<s>
On	O
June	O
4	O
,	O
2014	O
,	O
DragonFly	B-Application
3.8.0	O
was	O
released	O
featuring	O
support	O
for	O
HAMMER2	B-Application
,	O
although	O
the	O
file	O
system	O
was	O
said	O
to	O
be	O
not	O
ready	O
for	O
use	O
.	O
</s>
<s>
On	O
October	O
16	O
,	O
2017	O
,	O
DragonFly	B-Application
5.0	O
was	O
released	O
with	O
bootable	B-Operating_System
support	O
for	O
HAMMER2	B-Application
,	O
though	O
file-system	O
status	O
was	O
marked	O
as	O
experimental	O
.	O
</s>
<s>
HAMMER2	B-Application
had	O
a	O
long	O
incubation	O
and	O
development	O
period	O
before	O
it	O
officially	O
entered	O
production	O
in	O
April	O
2018	O
,	O
as	O
the	O
recommended	O
root	B-Application
filesystem	I-Application
in	O
the	O
Dragonfly	B-Application
BSD	I-Application
5.2	O
release	O
.	O
</s>
<s>
Dillon	O
continues	O
to	O
actively	O
develop	O
and	O
maintain	O
HAMMER2	B-Application
as	O
of	O
June	O
2020	O
.	O
</s>
