<s>
Object	B-Application
storage	I-Application
(	O
also	O
known	O
as	O
object-based	B-Application
storage	I-Application
)	O
is	O
a	O
computer	B-General_Concept
data	I-General_Concept
storage	I-General_Concept
that	O
manages	O
data	O
as	O
objects	O
,	O
as	O
opposed	O
to	O
other	O
storage	O
architectures	O
like	O
file	B-Application
systems	I-Application
which	O
manages	O
data	O
as	O
a	O
file	O
hierarchy	O
,	O
and	O
block	B-General_Concept
storage	I-General_Concept
which	O
manages	O
data	O
as	O
blocks	O
within	O
sectors	O
and	O
tracks	O
.	O
</s>
<s>
Object	B-Application
storage	I-Application
can	O
be	O
implemented	O
at	O
multiple	O
levels	O
,	O
including	O
the	O
device	O
level	O
(	O
object-storage	O
device	O
)	O
,	O
the	O
system	O
level	O
,	O
and	O
the	O
interface	O
level	O
.	O
</s>
<s>
In	O
each	O
case	O
,	O
object	B-Application
storage	I-Application
seeks	O
to	O
enable	O
capabilities	O
not	O
addressed	O
by	O
other	O
storage	O
architectures	O
,	O
like	O
interfaces	O
that	O
are	O
directly	O
programmable	O
by	O
the	O
application	O
,	O
a	O
namespace	O
that	O
can	O
span	O
multiple	O
instances	O
of	O
physical	O
hardware	O
,	O
and	O
data-management	O
functions	O
like	O
data	B-Architecture
replication	I-Architecture
and	O
data	O
distribution	O
at	O
object-level	O
granularity	O
.	O
</s>
<s>
Object	B-Application
storage	I-Application
systems	O
allow	O
retention	O
of	O
massive	O
amounts	O
of	O
unstructured	B-Application
data	I-Application
in	O
which	O
data	O
is	O
written	O
once	O
and	O
read	O
once	O
(	O
or	O
many	O
times	O
)	O
.	O
</s>
<s>
Object	B-Application
storage	I-Application
is	O
used	O
for	O
purposes	O
such	O
as	O
storing	O
objects	O
like	O
videos	O
and	O
photos	O
on	O
Facebook	B-Application
,	O
songs	O
on	O
Spotify	B-Application
,	O
or	O
files	O
in	O
online	O
collaboration	O
services	O
,	O
such	O
as	O
Dropbox	B-Application
.	O
</s>
<s>
One	O
of	O
the	O
limitations	O
with	O
object	B-Application
storage	I-Application
is	O
that	O
it	O
is	O
not	O
intended	O
for	O
transactional	B-General_Concept
data	I-General_Concept
,	O
as	O
object	B-Application
storage	I-Application
was	O
not	O
designed	O
to	O
replace	O
NAS	B-Application
file	B-Application
access	I-Application
and	O
sharing	O
;	O
it	O
does	O
not	O
support	O
the	O
locking	O
and	O
sharing	O
mechanisms	O
needed	O
to	O
maintain	O
a	O
single	O
,	O
accurately	O
updated	O
version	O
of	O
a	O
file	O
.	O
</s>
<s>
Object	B-Application
storage	I-Application
was	O
proposed	O
at	O
Gibson	O
's	O
Carnegie	O
Mellon	O
University	O
lab	O
as	O
a	O
research	O
project	O
in	O
1996	O
.	O
</s>
<s>
Fine	O
grained	O
access	O
control	O
through	O
object	B-Application
storage	I-Application
architecture	O
was	O
further	O
described	O
by	O
one	O
of	O
the	O
NASD	O
team	O
,	O
Howard	O
Gobioff	O
,	O
who	O
later	O
was	O
one	O
of	O
the	O
inventors	O
of	O
the	O
Google	B-Application
File	I-Application
System	I-Application
.	O
</s>
<s>
Other	O
related	O
work	O
includes	O
the	O
Coda	B-Application
filesystem	B-Application
project	O
at	O
Carnegie	O
Mellon	O
,	O
which	O
started	O
in	O
1987	O
,	O
and	O
spawned	O
the	O
Lustre	B-Application
file	I-Application
system	I-Application
.	O
</s>
<s>
Seagate	O
Technology	O
played	O
a	O
central	O
role	O
in	O
the	O
development	O
of	O
object	B-Application
storage	I-Application
.	O
</s>
<s>
This	O
paper	O
was	O
proposed	O
to	O
INCITS	O
T-10	O
(	O
International	O
Committee	O
for	O
Information	O
Technology	O
Standards	O
)	O
with	O
a	O
goal	O
to	O
form	O
a	O
committee	O
and	O
design	O
a	O
specification	O
based	O
on	O
the	O
SCSI	B-Architecture
interface	O
protocol	O
.	O
</s>
<s>
This	O
defined	O
objects	O
as	O
abstracted	O
data	O
,	O
with	O
unique	O
identifiers	O
and	O
metadata	O
,	O
how	O
objects	O
related	O
to	O
file	B-Application
systems	I-Application
,	O
along	O
with	O
many	O
other	O
innovative	O
concepts	O
.	O
</s>
<s>
The	O
presentation	O
revealed	O
an	O
IP	O
Agreement	O
that	O
had	O
been	O
signed	O
in	O
February	O
1997	O
between	O
the	O
original	O
collaborators	O
(	O
with	O
Seagate	O
represented	O
by	O
Anderson	O
and	O
Chris	O
Malakapalli	O
)	O
and	O
covered	O
the	O
benefits	O
of	O
object	B-Application
storage	I-Application
,	O
scalable	O
computing	O
,	O
platform	O
independence	O
,	O
and	O
storage	O
management	O
.	O
</s>
<s>
One	O
of	O
the	O
design	O
principles	O
of	O
object	B-Application
storage	I-Application
is	O
to	O
abstract	O
some	O
of	O
the	O
lower	O
layers	O
of	O
storage	O
away	O
from	O
the	O
administrators	O
and	O
applications	O
.	O
</s>
<s>
Administrators	O
do	O
not	O
have	O
to	O
perform	O
lower-level	O
storage	O
functions	O
like	O
constructing	O
and	O
managing	O
logical	O
volumes	O
to	O
utilize	O
disk	B-General_Concept
capacity	I-General_Concept
or	O
setting	O
RAID	B-Architecture
levels	O
to	O
deal	O
with	O
disk	O
failure	O
.	O
</s>
<s>
Object	B-Application
storage	I-Application
also	O
allows	O
the	O
addressing	O
and	O
identification	O
of	O
individual	O
objects	O
by	O
more	O
than	O
just	O
file	O
name	O
and	O
file	O
path	O
.	O
</s>
<s>
Object	B-Application
storage	I-Application
adds	O
a	O
unique	O
identifier	O
within	O
a	O
bucket	O
,	O
or	O
across	O
the	O
entire	O
system	O
,	O
to	O
support	O
much	O
larger	O
namespaces	O
and	O
eliminate	O
name	O
collisions	O
.	O
</s>
<s>
Object	B-Application
storage	I-Application
explicitly	O
separates	O
file	O
metadata	O
from	O
data	O
to	O
support	O
additional	O
capabilities	O
.	O
</s>
<s>
As	O
opposed	O
to	O
fixed	O
metadata	O
in	O
file	B-Application
systems	I-Application
(	O
filename	O
,	O
creation	O
date	O
,	O
type	O
,	O
etc	O
.	O
</s>
<s>
)	O
,	O
object	B-Application
storage	I-Application
provides	O
for	O
full	O
function	O
,	O
custom	O
,	O
object-level	O
metadata	O
in	O
order	O
to	O
:	O
</s>
<s>
Additionally	O
,	O
in	O
some	O
object-based	O
file-system	B-Application
implementations	O
:	O
</s>
<s>
Object-based	B-Application
storage	I-Application
devices	I-Application
(	O
OSD	O
)	O
as	O
well	O
as	O
some	O
software	O
implementations	O
(	O
e.g.	O
,	O
DataCore	O
Swarm	O
)	O
manage	O
metadata	O
and	O
data	O
at	O
the	O
storage	O
device	O
level	O
:	O
</s>
<s>
Object	B-Application
storage	I-Application
provides	O
programmatic	O
interfaces	O
to	O
allow	O
applications	O
to	O
manipulate	O
data	O
.	O
</s>
<s>
At	O
the	O
base	O
level	O
,	O
this	O
includes	O
Create	B-General_Concept
,	I-General_Concept
read	I-General_Concept
,	I-General_Concept
update	I-General_Concept
and	I-General_Concept
delete	I-General_Concept
(	O
CRUD	B-General_Concept
)	O
functions	O
for	O
basic	O
read	O
,	O
write	O
and	O
delete	O
operations	O
.	O
</s>
<s>
Some	O
object	B-Application
storage	I-Application
implementations	O
go	O
further	O
,	O
supporting	O
additional	O
functionality	O
like	O
object/file	O
versioning	O
,	O
object	O
replication	B-Architecture
,	O
life-cycle	O
management	O
and	O
movement	O
of	O
objects	O
between	O
different	O
tiers	O
and	O
types	O
of	O
storage	O
.	O
</s>
<s>
Most	O
API	O
implementations	O
are	O
REST-based	O
,	O
allowing	O
the	O
use	O
of	O
many	O
standard	O
HTTP	B-Protocol
calls	O
.	O
</s>
<s>
Some	O
notable	O
examples	O
are	O
Amazon	B-General_Concept
Web	I-General_Concept
Services	I-General_Concept
S3	I-General_Concept
,	O
which	O
debuted	O
in	O
March	O
2006	O
,	O
Microsoft	B-Application
Azure	I-Application
Blob	O
Storage	O
,	O
Rackspace	O
Files	O
(	O
whose	O
code	O
was	O
donated	O
in	O
2010	O
to	O
Openstack	O
project	O
and	O
released	O
as	O
OpenStack	O
Swift	O
)	O
,	O
and	O
Google	B-General_Concept
Cloud	I-General_Concept
Storage	I-General_Concept
released	O
in	O
May	O
2010	O
.	O
</s>
<s>
Some	O
distributed	O
file	B-Application
systems	I-Application
use	O
an	O
object-based	O
architecture	O
,	O
where	O
file	O
metadata	O
is	O
stored	O
in	O
metadata	O
servers	O
and	O
file	O
data	O
is	O
stored	O
in	O
object	B-Application
storage	I-Application
servers	O
.	O
</s>
<s>
File	B-Application
system	I-Application
client	O
software	O
interacts	O
with	O
the	O
distinct	O
servers	O
,	O
and	O
abstracts	O
them	O
to	O
present	O
a	O
full	O
file	B-Application
system	I-Application
to	O
users	O
and	O
applications	O
.	O
</s>
<s>
Some	O
early	O
incarnations	O
of	O
object	B-Application
storage	I-Application
were	O
used	O
for	O
archiving	O
,	O
as	O
implementations	O
were	O
optimized	O
for	O
data	O
services	O
like	O
immutability	O
,	O
not	O
performance	O
.	O
</s>
<s>
EMC	B-Data_Structure
Centera	I-Data_Structure
and	O
Hitachi	O
HCP	O
(	O
formerly	O
known	O
as	O
HCAP	O
)	O
are	O
two	O
commonly	O
cited	O
object	B-Application
storage	I-Application
products	O
for	O
archiving	O
.	O
</s>
<s>
Another	O
example	O
is	O
Quantum	O
ActiveScale	O
Object	B-Application
Storage	I-Application
Platform	O
.	O
</s>
<s>
Lured	O
by	O
the	O
incredible	O
growth	O
of	O
"	O
captive	O
"	O
storage	B-General_Concept
systems	I-General_Concept
within	O
web	O
applications	O
like	O
Yahoo	O
Mail	O
and	O
the	O
early	O
success	O
of	O
cloud	O
storage	O
,	O
object-storage	O
systems	O
promised	O
the	O
scale	O
and	O
capabilities	O
of	O
cloud	O
storage	O
,	O
with	O
the	O
ability	O
to	O
deploy	O
the	O
system	O
within	O
an	O
enterprise	O
,	O
or	O
at	O
an	O
aspiring	O
cloud-storage	O
service	O
provider	O
.	O
</s>
<s>
A	O
few	O
object-storage	O
systems	O
support	O
Unified	O
File	O
and	O
Object	B-Application
storage	I-Application
,	O
allowing	O
clients	O
to	O
store	O
objects	O
on	O
a	O
storage	B-General_Concept
system	I-General_Concept
while	O
simultaneously	O
other	O
clients	O
store	O
files	O
on	O
the	O
same	O
storage	B-General_Concept
system	I-General_Concept
.	O
</s>
<s>
Other	O
vendors	O
in	O
the	O
area	O
of	O
Hybrid	B-General_Concept
cloud	I-General_Concept
storage	I-General_Concept
are	O
using	O
Cloud	O
storage	O
gateways	O
to	O
provide	O
a	O
file	B-Application
access	I-Application
layer	O
over	O
object	B-Application
storage	I-Application
,	O
implementing	O
file	B-Application
access	I-Application
protocols	O
such	O
as	O
SMB	O
and	O
NFS	O
.	O
</s>
<s>
Facebook	B-Application
famously	O
invented	O
their	O
own	O
object-storage	O
software	O
,	O
code-named	O
Haystack	O
,	O
to	O
address	O
their	O
particular	O
massive-scale	O
photo	O
management	O
needs	O
efficiently	O
.	O
</s>
<s>
Object	B-Application
storage	I-Application
at	O
the	O
protocol	O
and	O
device	O
layer	O
was	O
proposed	O
20	O
years	O
ago	O
and	O
approved	O
for	O
the	O
SCSI	B-Architecture
command	O
set	O
nearly	O
10	O
years	O
ago	O
as	O
"	O
Object-based	B-Application
Storage	I-Application
Device	I-Application
Commands	O
"	O
(	O
OSD	O
)	O
,	O
however	O
,	O
it	O
had	O
not	O
been	O
put	O
into	O
production	O
until	O
the	O
development	O
of	O
the	O
Seagate	O
Kinetic	O
Open	O
Storage	O
platform	O
.	O
</s>
<s>
The	O
SCSI	B-Architecture
command	O
set	O
for	O
Object	B-Application
Storage	I-Application
Devices	I-Application
was	O
developed	O
by	O
a	O
working	O
group	O
of	O
the	O
SNIA	O
for	O
the	O
T10	O
committee	O
of	O
the	O
International	O
Committee	O
for	O
Information	O
Technology	O
Standards	O
(	O
INCITS	O
)	O
.	O
</s>
<s>
T10	O
is	O
responsible	O
for	O
all	O
SCSI	B-Architecture
standards	O
.	O
</s>
<s>
One	O
of	O
the	O
first	O
object-storage	O
products	O
,	O
Lustre	B-Application
,	O
is	O
used	O
in	O
70%	O
of	O
the	O
Top	O
100	O
supercomputers	O
and	O
~	O
50%	O
of	O
the	O
Top	B-Operating_System
500	I-Operating_System
.	O
</s>
<s>
As	O
of	O
June	O
16	O
,	O
2013	O
,	O
this	O
includes	O
7	O
of	O
the	O
top	O
10	O
,	O
including	O
the	O
current	O
fourth	O
fastest	O
system	O
on	O
the	O
list	O
-	O
China	O
's	O
Tianhe-2	O
and	O
the	O
seventh	O
fastest	O
,	O
the	O
Titan	B-Device
supercomputer	I-Device
at	O
the	O
Oak	O
Ridge	O
National	O
Laboratory	O
.	O
</s>
<s>
Newer	O
object	B-Application
storage	I-Application
systems	O
have	O
also	O
gotten	O
some	O
traction	O
,	O
particularly	O
around	O
very	O
large	O
custom	O
applications	O
like	O
eBay	O
's	O
auction	O
site	O
,	O
where	O
EMC	O
Atmos	O
is	O
used	O
to	O
manage	O
over	O
500	O
million	O
objects	O
a	O
day	O
.	O
</s>
<s>
On	O
July	O
1	O
,	O
2014	O
,	O
Los	O
Alamos	O
National	O
Lab	O
chose	O
the	O
Scality	B-General_Concept
RING	I-General_Concept
as	O
the	O
basis	O
for	O
a	O
500-petabyte	O
storage	O
environment	O
,	O
which	O
would	O
be	O
among	O
the	O
largest	O
ever	O
.	O
</s>
<s>
"	O
Captive	O
"	O
object	B-Application
storage	I-Application
systems	O
like	O
Facebook	B-Application
's	O
Haystack	O
have	O
scaled	O
impressively	O
.	O
</s>
<s>
Facebook	B-Application
more	O
recently	O
stated	O
that	O
they	O
were	O
adding	O
350	O
million	O
photos	O
a	O
day	O
and	O
were	O
storing	O
240	O
billion	O
photos	O
.	O
</s>
<s>
As	O
the	O
storage	O
back-end	O
to	O
many	O
popular	O
applications	O
like	O
Smugmug	B-Algorithm
and	O
Dropbox	B-Application
,	O
Amazon	B-General_Concept
S3	I-General_Concept
has	O
grown	O
to	O
massive	O
scale	O
,	O
citing	O
over	O
2-trillion	O
objects	O
stored	O
in	O
April	O
2013	O
.	O
</s>
<s>
Windows	B-Application
Azure	I-Application
Storage	O
manages	O
Blobs	O
(	O
user	O
files	O
)	O
,	O
Tables	O
(	O
structured	O
storage	O
)	O
,	O
and	O
Queues	O
(	O
message	O
delivery	O
)	O
and	O
counts	O
them	O
all	O
as	O
objects	O
.	O
</s>
<s>
In	O
2019	O
,	O
IDC	O
rated	O
Dell	O
EMC	O
,	O
Hitachi	O
Data	O
Systems	O
,	O
IBM	O
,	O
NetApp	O
,	O
and	O
Scality	B-General_Concept
as	O
leaders	O
.	O
</s>
<s>
These	O
are	O
set	O
on	O
objects	O
by	O
the	O
higher-level	O
storage	B-General_Concept
systems	I-General_Concept
that	O
use	O
the	O
OSD	O
for	O
persistent	O
storage	O
.	O
</s>
<s>
This	O
ability	O
reduces	O
the	O
number	O
of	O
times	O
a	O
high-level	O
storage	B-General_Concept
system	I-General_Concept
has	O
to	O
cross	O
the	O
interface	O
to	O
the	O
OSD	O
,	O
which	O
can	O
improve	O
overall	O
efficiency	O
.	O
</s>
<s>
A	O
second	O
generation	O
of	O
the	O
SCSI	B-Architecture
command	O
set	O
,	O
"	O
Object-Based	B-Application
Storage	I-Application
Devices	I-Application
-	O
2	O
"	O
(	O
OSD-2	O
)	O
added	O
support	O
for	O
snapshots	B-Application
,	O
collections	O
of	O
objects	O
,	O
and	O
improved	O
error	O
handling	O
.	O
</s>
<s>
A	O
snapshot	B-Application
is	O
a	O
point-in-time	O
copy	O
of	O
all	O
the	O
objects	O
in	O
a	O
partition	O
into	O
a	O
new	O
partition	O
.	O
</s>
<s>
The	O
OSD	O
can	O
implement	O
a	O
space-efficient	O
copy	O
using	O
copy-on-write	B-Language
techniques	O
so	O
that	O
the	O
two	O
partitions	O
share	O
objects	O
that	O
are	O
unchanged	O
between	O
the	O
snapshots	B-Application
,	O
or	O
the	O
OSD	O
might	O
physically	O
copy	O
the	O
data	O
to	O
the	O
new	O
partition	O
.	O
</s>
<s>
The	O
standard	O
defines	O
clones	O
,	O
which	O
are	O
writeable	O
,	O
and	O
snapshots	B-Application
,	O
which	O
are	O
read-only	O
.	O
</s>
<s>
The	O
higher-level	O
storage	B-General_Concept
system	I-General_Concept
that	O
uses	O
the	O
OSD	O
can	O
query	O
this	O
collection	O
and	O
take	O
corrective	O
action	O
as	O
necessary	O
.	O
</s>
<s>
The	O
border	O
between	O
an	O
object	O
store	O
and	O
a	O
key-value	B-Data_Structure
store	I-Data_Structure
is	O
blurred	O
,	O
with	O
key-value	B-Data_Structure
stores	I-Data_Structure
being	O
sometimes	O
loosely	O
referred	O
to	O
as	O
object	O
stores	O
.	O
</s>
<s>
A	O
traditional	O
block	B-General_Concept
storage	I-General_Concept
interface	O
uses	O
a	O
series	O
of	O
fixed	O
size	O
blocks	O
which	O
are	O
numbered	O
starting	O
at	O
0	O
.	O
</s>
<s>
With	O
a	O
key-value	B-Data_Structure
store	I-Data_Structure
,	O
data	O
is	O
identified	O
by	O
a	O
key	O
rather	O
than	O
a	O
LBN	O
.	O
</s>
<s>
Several	O
data	O
stores	O
also	O
implement	O
key-value	B-Data_Structure
stores	I-Data_Structure
such	O
as	O
Memcached	O
,	O
Redis	O
and	O
CouchDB	O
.	O
</s>
<s>
Object	O
stores	O
are	O
similar	O
to	O
key-value	B-Data_Structure
stores	I-Data_Structure
in	O
two	O
respects	O
.	O
</s>
<s>
There	O
are	O
,	O
however	O
,	O
a	O
few	O
key	O
differences	O
between	O
key-value	B-Data_Structure
stores	I-Data_Structure
and	O
object	O
stores	O
.	O
</s>
<s>
Second	O
,	O
object	O
stores	O
are	O
optimized	O
for	O
large	O
amounts	O
of	O
data	O
(	O
hundreds	O
of	O
megabytes	O
or	O
even	O
gigabytes	O
)	O
,	O
whereas	O
for	O
key-value	B-Data_Structure
stores	I-Data_Structure
the	O
value	O
is	O
expected	O
to	O
be	O
relatively	O
small	O
(	O
kilobytes	O
)	O
.	O
</s>
<s>
Finally	O
,	O
object	O
stores	O
usually	O
offer	O
weaker	O
consistency	O
guarantees	O
such	O
as	O
eventual	B-General_Concept
consistency	I-General_Concept
,	O
whereas	O
key-value	B-Data_Structure
stores	I-Data_Structure
offer	O
strong	B-General_Concept
consistency	I-General_Concept
.	O
</s>
