<s>
Aerospike	B-Operating_System
Database	I-Operating_System
is	O
a	O
flash	B-Device
memory	I-Device
and	O
in-memory	B-General_Concept
open	B-License
source	I-License
distributed	B-Architecture
key	B-Data_Structure
value	I-Data_Structure
NoSQL	B-General_Concept
database	O
management	O
system	O
,	O
marketed	O
by	O
the	O
company	O
also	O
named	O
Aerospike	B-Operating_System
.	O
</s>
<s>
Aerospike	B-Operating_System
was	O
first	O
known	O
as	O
Citrusleaf	O
.	O
</s>
<s>
In	O
August	O
2012	O
,	O
the	O
company	O
-	O
which	O
had	O
been	O
providing	O
its	O
database	O
since	O
2010	O
-	O
rebranded	O
both	O
the	O
company	O
and	O
software	O
name	O
to	O
Aerospike	B-Operating_System
.	O
</s>
<s>
The	O
name	O
"	O
Aerospike	B-Operating_System
"	O
is	O
derived	O
from	O
the	O
aerospike	B-Operating_System
engine	O
,	O
a	O
type	O
of	O
rocket	O
nozzle	O
that	O
is	O
able	O
to	O
maintain	O
its	O
output	O
efficiency	O
over	O
a	O
large	O
range	O
of	O
altitudes	O
,	O
and	O
is	O
intended	O
to	O
refer	O
to	O
the	O
software	O
's	O
ability	O
to	O
scale	O
up	O
.	O
</s>
<s>
In	O
2012	O
,	O
Aerospike	B-Operating_System
acquired	O
AlchemyDB	O
,	O
and	O
integrated	O
the	O
two	O
databases	O
 '	O
functions	O
,	O
including	O
the	O
addition	O
of	O
a	O
relational	O
data	O
management	O
system	O
.	O
</s>
<s>
On	O
June	O
24	O
,	O
2014	O
,	O
Aerospike	B-Operating_System
was	O
opensourced	O
under	O
the	O
AGPL	O
3.0	O
license	O
for	O
the	O
Aerospike	B-Operating_System
database	I-Operating_System
server	I-Operating_System
and	O
the	O
Apache	B-Application
License	I-Application
Version	O
2.0	O
for	O
its	O
Aerospike	B-Operating_System
client	O
software	O
development	O
kit	O
.	O
</s>
<s>
Aerospike	B-Operating_System
Database	I-Operating_System
is	O
modeled	O
under	O
the	O
shared-nothing	B-Operating_System
architecture	I-Operating_System
and	O
written	O
in	O
C	B-Language
.	O
It	O
operates	O
in	O
three	O
layers	O
:	O
a	O
data	O
storage	O
layer	O
,	O
a	O
self-managed	O
distribution	O
layer	O
,	O
and	O
a	O
cluster-aware	O
client	O
layer	O
.	O
</s>
<s>
Aerospike	B-Operating_System
uses	O
hybrid	O
memory	O
architecture	O
:	O
the	O
database	B-Data_Structure
indices	I-Data_Structure
are	O
stored	O
fully	O
in	O
main	O
random-access	B-Architecture
memory	I-Architecture
,	O
while	O
the	O
data	O
is	O
stored	O
on	O
a	O
persistent	O
device	O
using	O
the	O
data	O
layer	O
.	O
</s>
<s>
The	O
data	O
layer	O
stores	O
the	O
data	O
in	O
solid-state	B-Device
drive	I-Device
,	O
NVMe	B-Application
or	O
Persistent	B-Library
memory	I-Library
.	O
</s>
<s>
This	O
architecture	O
to	O
fetch	O
all	O
records	O
from	O
the	O
persistent	O
device	O
and	O
void	O
the	O
use	O
of	O
data	B-General_Concept
cache	I-General_Concept
.	O
</s>
<s>
Aerospike	B-Operating_System
also	O
provides	O
the	O
ability	O
to	O
store	O
the	O
data	O
fully	O
in	O
RAM	B-Architecture
,	O
thus	O
acting	O
as	O
an	O
in-memory	B-General_Concept
database	I-General_Concept
.	O
</s>
<s>
In	O
that	O
case	O
,	O
data	O
would	O
be	O
persisted	O
to	O
either	O
SSD	B-Device
,	O
NVMe	B-Application
,	O
PMEM	O
or	O
traditional	O
rotational	B-Device
media	I-Device
.	O
</s>
<s>
Aerospike	B-Operating_System
provides	O
single-record	O
ACID	B-General_Concept
transactions	I-General_Concept
.	O
</s>
<s>
The	O
distribution	O
layer	O
is	O
responsible	O
to	O
replicate	O
the	O
data	O
across	O
nodes	O
to	O
ensure	O
the	O
durability	B-General_Concept
and	O
immediate	B-General_Concept
consistency	I-General_Concept
properties	O
of	O
the	O
transaction	O
.	O
</s>
<s>
Since	O
version	O
4.0	O
(	O
2018	O
)	O
,	O
Aerospike	B-Operating_System
Database	I-Operating_System
can	O
be	O
configured	O
both	O
as	O
Available	O
and	O
Partition-tolerant	O
(	O
AP	O
)	O
or	O
Consistent	O
and	O
Partition-tolerant	O
(	O
CP	O
)	O
under	O
the	O
CAP	B-Operating_System
theorem	I-Operating_System
.	O
</s>
<s>
The	O
clustering	O
is	O
done	O
using	O
heartbeats	B-Operating_System
and	O
Paxos	B-Operating_System
based	O
gossip	B-Operating_System
protocol	I-Operating_System
algorithm	O
.	O
</s>
<s>
Defragmenter	O
removes	O
data	O
blocks	O
that	O
have	O
been	O
deleted	O
,	O
and	O
Evictor	O
frees	O
RAM	B-Architecture
space	O
by	O
removing	O
references	O
to	O
expired	O
records	O
.	O
</s>
