<s>
Ceph	O
(	O
pronounced	O
)	O
is	O
an	O
open-source	O
software-defined	O
storage	B-General_Concept
platform	B-Device
that	O
implements	O
object	B-Application
storage	I-Application
on	O
a	O
single	O
distributed	O
computer	B-Architecture
cluster	I-Architecture
and	O
provides	O
3-in-1	O
interfaces	O
for	O
object-	O
,	O
block	B-General_Concept
-	I-General_Concept
and	O
file-level	O
storage	B-General_Concept
.	O
</s>
<s>
Ceph	O
aims	O
primarily	O
for	O
completely	O
distributed	O
operation	O
without	O
a	O
single	B-Architecture
point	I-Architecture
of	I-Architecture
failure	I-Architecture
,	O
scalability	O
to	O
the	O
exabyte	O
level	O
,	O
and	O
to	O
be	O
freely	O
available	O
.	O
</s>
<s>
Since	O
version	O
12	O
,	O
Ceph	O
does	O
not	O
rely	O
on	O
other	O
filesystems	B-Application
and	O
can	O
directly	O
manage	O
HDDs	O
and	O
SSDs	B-Device
with	O
its	O
own	O
storage	B-General_Concept
backend	O
BlueStore	O
and	O
can	O
completely	O
self	O
reliantly	O
expose	O
a	O
POSIX	O
filesystem	B-Application
.	O
</s>
<s>
Ceph	O
replicates	B-Architecture
data	O
and	O
makes	O
it	O
fault-tolerant	B-General_Concept
,	O
using	O
commodity	B-Device
hardware	I-Device
and	O
Ethernet	O
IP	O
and	O
requiring	O
no	O
specific	O
hardware	O
support	O
.	O
</s>
<s>
The	O
Ceph	O
’s	O
system	O
offers	O
disaster	O
recovery	O
and	O
data	B-Architecture
redundancy	I-Architecture
through	O
techniques	O
such	O
as	O
replication	B-Architecture
,	O
erasure	O
coding	O
,	O
snapshots	O
and	O
storage	B-General_Concept
cloning	O
.	O
</s>
<s>
As	O
a	O
result	O
of	O
its	O
design	O
,	O
the	O
system	O
is	O
both	O
self-healing	B-General_Concept
and	O
self-managing	B-General_Concept
,	O
aiming	O
to	O
minimize	O
administration	O
time	O
and	O
other	O
costs	O
.	O
</s>
<s>
In	O
this	O
way	O
,	O
administrators	O
have	O
a	O
single	O
,	O
consolidated	O
system	O
that	O
collects	O
the	O
storage	B-General_Concept
within	O
a	O
common	O
management	O
framework	O
.	O
</s>
<s>
Ceph	O
consolidates	O
several	O
storage	B-General_Concept
use	O
cases	O
and	O
improves	O
resource	O
utilization	O
.	O
</s>
<s>
Some	O
of	O
the	O
big	O
production	O
Ceph	O
deployments	O
include	O
CERN	O
,	O
OVH	B-General_Concept
and	O
DigitalOcean	B-Application
.	O
</s>
<s>
Ceph	O
employs	O
five	O
distinct	O
kinds	O
of	O
daemons	B-Operating_System
:	O
</s>
<s>
Metadata	O
servers	O
(	O
)	O
that	O
cache	O
and	O
broker	O
access	O
to	O
inodes	B-Application
and	O
directories	B-Application
inside	O
a	O
CephFS	B-Application
filesystem	B-Application
.	O
</s>
<s>
Ceph	O
does	O
striping	B-General_Concept
of	O
individual	O
files	O
across	O
multiple	O
nodes	O
to	O
achieve	O
higher	O
throughput	O
,	O
similar	O
to	O
how	O
RAID0	O
stripes	O
partitions	O
across	O
multiple	O
hard	B-Device
drives	I-Device
.	O
</s>
<s>
Adaptive	O
load	B-Application
balancing	I-Application
is	O
supported	O
whereby	O
frequently	O
accessed	O
objects	O
are	O
replicated	O
over	O
more	O
nodes	O
.	O
</s>
<s>
,	O
BlueStore	O
is	O
the	O
default	O
and	O
recommended	O
storage	B-General_Concept
type	O
for	O
production	O
environments	O
,	O
which	O
is	O
Ceph	O
's	O
own	O
storage	B-General_Concept
implementation	O
providing	O
better	O
latency	O
and	O
configurability	O
than	O
the	O
filestore	O
backend	O
,	O
and	O
avoiding	O
the	O
shortcomings	O
of	O
the	O
filesystem	B-Application
based	O
storage	B-General_Concept
involving	O
additional	O
processing	O
and	O
caching	O
layers	O
.	O
</s>
<s>
The	O
filestore	O
backend	O
is	O
still	O
considered	O
useful	O
and	O
very	O
stable	O
;	O
XFS	B-Application
used	O
to	O
be	O
the	O
recommended	O
underlying	O
filesystem	B-Application
type	O
for	O
production	O
environments	O
,	O
while	O
Btrfs	B-Operating_System
was	O
recommended	O
for	O
non-production	O
environments	O
.	O
</s>
<s>
ext4	B-Application
filesystems	I-Application
were	O
not	O
recommended	O
because	O
of	O
resulting	O
limitations	O
on	O
the	O
maximum	O
RADOS	O
objects	O
length	O
.	O
</s>
<s>
Even	O
using	O
BlueStore	O
,	O
XFS	B-Application
is	O
used	O
for	O
a	O
small	O
partition	O
of	O
metadata	O
.	O
</s>
<s>
Ceph	O
implements	O
distributed	O
object	B-Application
storage	I-Application
-	O
BlueStore	O
.	O
</s>
<s>
RADOS	O
gateway	O
(	O
)	O
expose	O
the	O
object	B-Application
storage	I-Application
layer	O
as	O
an	O
interface	O
compatible	O
with	O
Amazon	B-General_Concept
S3	I-General_Concept
.	O
</s>
<s>
These	O
are	O
often	O
capacitive	O
disks	O
which	O
are	O
associated	O
with	O
Ceph	O
's	O
S3	O
object	B-Application
storage	I-Application
for	O
use	O
cases	O
:	O
Big	B-Application
Data	I-Application
(	O
datalake	O
)	O
,	O
Backup	O
&	O
Archives	O
,	O
IOT	B-Operating_System
,	O
media	O
,	O
video	O
recording	O
,	O
etc	O
.	O
</s>
<s>
Ceph	O
's	O
software	B-Library
libraries	I-Library
provide	O
client	O
applications	O
with	O
direct	O
access	O
to	O
the	O
reliable	O
autonomic	O
distributed	O
object	O
store	O
(	O
RADOS	O
)	O
object-based	B-Application
storage	I-Application
system	O
,	O
and	O
also	O
provide	O
a	O
foundation	O
for	O
some	O
of	O
Ceph	O
's	O
features	O
,	O
including	O
RADOS	O
Block	O
Device	O
(	O
RBD	O
)	O
,	O
RADOS	O
Gateway	O
,	O
and	O
the	O
Ceph	O
File	B-Application
System	I-Application
.	O
</s>
<s>
In	O
this	O
way	O
,	O
administrators	O
can	O
maintain	O
their	O
storage	B-General_Concept
devices	O
as	O
a	O
unified	O
system	O
,	O
which	O
makes	O
it	O
easier	O
to	O
replicate	O
and	O
protect	O
the	O
data	O
.	O
</s>
<s>
The	O
"	O
librados	O
"	O
software	B-Library
libraries	I-Library
provide	O
access	O
in	O
C	B-Language
,	O
C++	B-Language
,	O
Java	B-Language
,	O
PHP	B-Application
,	O
and	O
Python	B-Language
.	O
</s>
<s>
The	O
RADOS	O
Gateway	O
also	O
exposes	O
the	O
object	O
store	O
as	O
a	O
RESTful	O
interface	O
which	O
can	O
present	O
as	O
both	O
native	O
Amazon	B-General_Concept
S3	I-General_Concept
and	O
OpenStack	B-Application
Swift	O
APIs	O
.	O
</s>
<s>
Ceph	O
's	O
object	B-Application
storage	I-Application
system	O
allows	O
users	O
to	O
mount	O
Ceph	O
as	O
a	O
thin-provisioned	B-General_Concept
block	O
device	O
.	O
</s>
<s>
When	O
an	O
application	O
writes	O
data	O
to	O
Ceph	O
using	O
a	O
block	O
device	O
,	O
Ceph	O
automatically	O
stripes	O
and	O
replicates	B-Architecture
the	O
data	O
across	O
the	O
cluster	O
.	O
</s>
<s>
Ceph	O
's	O
RADOS	O
Block	O
Device	O
(	O
RBD	O
)	O
also	O
integrates	O
with	O
Kernel-based	B-Application
Virtual	I-Application
Machines	I-Application
(	O
KVMs	O
)	O
.	O
</s>
<s>
These	O
are	O
often	O
fast	O
disks	O
(	O
NVMe	B-Application
,	O
SSD	B-Device
)	O
which	O
are	O
associated	O
with	O
Ceph	O
's	O
block	B-General_Concept
storage	I-General_Concept
for	O
use	O
cases	O
,	O
including	O
databases	O
,	O
virtual	O
machines	O
,	O
data	O
analytics	O
,	O
artificial	O
intelligence	O
,	O
and	O
machine	O
learning	O
.	O
</s>
<s>
"	O
Ceph-RBD	O
"	O
interfaces	O
with	O
the	O
same	O
Ceph	O
object	B-Application
storage	I-Application
system	O
that	O
provides	O
the	O
librados	O
interface	O
and	O
the	O
CephFS	B-Application
file	B-Application
system	I-Application
,	O
and	O
it	O
stores	O
block	O
device	O
images	O
as	O
objects	O
.	O
</s>
<s>
By	O
striping	B-General_Concept
images	O
across	O
the	O
cluster	O
,	O
Ceph	O
improves	O
read	O
access	O
performance	O
for	O
large	O
block	O
device	O
images	O
.	O
</s>
<s>
"	O
Ceph-iSCSI	O
"	O
is	O
a	O
gateway	O
which	O
enables	O
access	O
to	O
distributed	O
,	O
highly	O
available	O
block	B-General_Concept
storage	I-General_Concept
from	O
any	O
Microsoft	B-Application
Windows	I-Application
and	O
VMware	B-Application
vSphere	I-Application
server	O
or	O
client	O
capable	O
of	O
speaking	O
the	O
iSCSI	B-Protocol
protocol	O
.	O
</s>
<s>
By	O
using	O
ceph-iscsi	O
on	O
one	O
or	O
more	O
iSCSI	B-Protocol
gateway	O
hosts	O
,	O
Ceph	O
RBD	O
images	O
become	O
available	O
as	O
Logical	O
Units	O
(	O
LUs	O
)	O
associated	O
with	O
iSCSI	B-Protocol
targets	O
,	O
which	O
can	O
be	O
accessed	O
in	O
an	O
optionally	O
load-balanced	B-Application
,	O
highly	O
available	O
fashion	O
.	O
</s>
<s>
Since	O
all	O
of	O
ceph-iscsi	O
configuration	O
is	O
stored	O
in	O
the	O
Ceph	O
RADOS	O
object	O
store	O
,	O
ceph-iscsi	O
gateway	O
hosts	O
are	O
inherently	O
without	O
persistent	O
state	O
and	O
thus	O
can	O
be	O
replaced	O
,	O
augmented	O
,	O
or	O
reduced	O
at	O
will	O
.	O
</s>
<s>
As	O
a	O
result	O
,	O
Ceph	O
Storage	B-General_Concept
enables	O
customers	O
to	O
run	O
a	O
truly	O
distributed	O
,	O
highly-available	O
,	O
resilient	O
,	O
and	O
self-healing	B-General_Concept
enterprise	O
storage	B-General_Concept
technology	O
on	O
commodity	B-Device
hardware	I-Device
and	O
an	O
entirely	O
open	B-Application
source	I-Application
platform	I-Application
.	O
</s>
<s>
The	O
block	O
device	O
can	O
be	O
virtualized	O
,	O
providing	O
block	B-General_Concept
storage	I-General_Concept
to	O
virtual	O
machines	O
,	O
in	O
virtualization	O
platforms	B-Device
such	O
as	O
Openshift	B-General_Concept
,	O
OpenStack	B-Application
,	O
Kubernetes	B-General_Concept
,	O
OpenNebula	B-Language
,	O
Ganeti	B-Language
,	O
Apache	B-General_Concept
CloudStack	I-General_Concept
and	O
Proxmox	B-Language
Virtual	I-Language
Environment	I-Language
.	O
</s>
<s>
Ceph	O
's	O
file	B-Application
system	I-Application
(	O
CephFS	B-Application
)	O
runs	O
on	O
top	O
of	O
the	O
same	O
object	B-Application
storage	I-Application
system	O
that	O
provides	O
object	B-Application
storage	I-Application
and	O
block	O
device	O
interfaces	O
.	O
</s>
<s>
The	O
Ceph	O
metadata	O
server	B-Architecture
cluster	I-Architecture
provides	O
a	O
service	O
that	O
maps	O
the	O
directories	B-Application
and	O
file	O
names	O
of	O
the	O
file	B-Application
system	I-Application
to	O
objects	O
stored	O
within	O
RADOS	O
clusters	O
.	O
</s>
<s>
The	O
metadata	O
server	B-Architecture
cluster	I-Architecture
can	O
expand	O
or	O
contract	O
,	O
and	O
it	O
can	O
rebalance	O
the	O
file	B-Application
system	I-Application
dynamically	O
to	O
distribute	O
data	O
evenly	O
among	O
cluster	O
hosts	O
.	O
</s>
<s>
Clients	O
mount	O
the	O
POSIX-compatible	O
file	B-Application
system	I-Application
using	O
a	O
Linux	B-Operating_System
kernel	I-Operating_System
client	O
.	O
</s>
<s>
An	O
older	O
FUSE-based	O
client	O
is	O
also	O
available	O
.	O
</s>
<s>
The	O
servers	O
run	O
as	O
regular	O
Unix	B-Operating_System
daemons	I-Operating_System
.	O
</s>
<s>
Ceph	O
's	O
file	B-Application
storage	I-Application
is	O
often	O
associated	O
with	O
log	O
collection	O
,	O
messaging	O
,	O
and	O
file	B-Application
storage	I-Application
.	O
</s>
<s>
It	O
's	O
beeing	O
developed	O
by	O
Ceph	O
community	O
on	O
LGPL-3	O
and	O
uses	O
Ceph-mgr	O
,	O
Python	B-Language
,	O
Angular	B-Language
framework	O
and	O
Grafana	B-Protocol
.	O
</s>
<s>
Main	O
goal	O
of	O
Crimson	O
is	O
minimizing	O
CPU	O
overhead	O
and	O
latency	O
,	O
because	O
modern	O
storage	B-General_Concept
devices	O
like	O
NVMe	B-Application
got	O
much	O
faster	O
than	O
HDD	B-Device
and	O
even	O
SSD	B-Device
,	O
but	O
CPUs	O
do	O
not	O
catch	O
up	O
with	O
that	O
change	O
.	O
</s>
<s>
There	O
are	O
few	O
reasons	O
for	O
creating	O
SeaStore	O
,	O
one	O
of	O
them	O
is	O
the	O
fact	O
,	O
that	O
transaction	O
support	O
in	O
the	O
BlueStore	O
are	O
provided	O
by	O
RocksDB	B-Language
,	O
which	O
would	O
mean	O
re-implementing	O
this	O
to	O
achieve	O
better	O
parallelism	O
.	O
</s>
<s>
Ceph	O
was	O
initially	O
created	O
by	O
Sage	O
Weil	O
for	O
his	O
doctoral	O
dissertation	O
,	O
which	O
was	O
advised	O
by	O
Professor	O
Scott	O
A	O
.	O
Brandt	O
at	O
the	O
Jack	O
Baskin	O
School	O
of	O
Engineering	O
,	O
University	O
of	O
California	O
,	O
Santa	O
Cruz	O
(	O
UCSC	O
)	O
,	O
and	O
sponsored	O
by	O
the	O
Advanced	B-General_Concept
Simulation	I-General_Concept
and	I-General_Concept
Computing	I-General_Concept
Program	I-General_Concept
(	O
ASC	O
)	O
,	O
including	O
Los	O
Alamos	O
National	O
Laboratory	O
(	O
LANL	O
)	O
,	O
Sandia	O
National	O
Laboratories	O
(	O
SNL	O
)	O
,	O
and	O
Lawrence	O
Livermore	O
National	O
Laboratory	O
(	O
LLNL	O
)	O
.	O
</s>
<s>
The	O
first	O
line	O
of	O
code	O
that	O
ended	O
up	O
being	O
part	O
of	O
Ceph	O
was	O
written	O
by	O
Sage	O
Weil	O
in	O
2004	O
while	O
at	O
a	O
summer	O
internship	O
at	O
LLNL	O
,	O
working	O
on	O
scalable	O
filesystem	B-Application
metadata	O
management	O
(	O
known	O
today	O
as	O
Ceph	O
's	O
MDS	O
)	O
.	O
</s>
<s>
In	O
2005	O
,	O
as	O
part	O
of	O
a	O
summer	O
project	O
initiated	O
by	O
Scott	O
A	O
.	O
Brandt	O
and	O
led	O
by	O
Carlos	O
Maltzahn	O
,	O
Sage	O
Weil	O
created	O
a	O
fully	O
functional	O
file	B-Application
system	I-Application
prototype	O
which	O
adopted	O
the	O
name	O
Ceph	O
.	O
</s>
<s>
Ceph	O
made	O
its	O
debut	O
with	O
Sage	O
Weil	O
giving	O
two	O
presentations	O
in	O
November	O
2006	O
,	O
one	O
at	O
USENIX	B-Operating_System
OSDI	O
2006	O
and	O
another	O
at	O
SC'06	O
.	O
</s>
<s>
On	O
March	O
19	O
,	O
2010	O
,	O
Linus	O
Torvalds	O
merged	O
the	O
Ceph	O
client	O
into	O
Linux	B-Operating_System
kernel	I-Operating_System
version	O
2.6.34	O
which	O
was	O
released	O
on	O
May	O
16	O
,	O
2010	O
.	O
</s>
<s>
In	O
2012	O
,	O
Weil	O
created	O
Inktank	O
Storage	B-General_Concept
for	O
professional	O
services	O
and	O
support	O
for	O
Ceph	O
.	O
</s>
<s>
In	O
October	O
2015	O
,	O
the	O
Ceph	O
Community	O
Advisory	O
Board	O
was	O
formed	O
to	O
assist	O
the	O
community	O
in	O
driving	O
the	O
direction	O
of	O
open	O
source	O
software-defined	O
storage	B-General_Concept
technology	O
.	O
</s>
<s>
In	O
November	O
2018	O
,	O
the	O
Linux	B-Operating_System
Foundation	O
launched	O
the	O
Ceph	O
Foundation	O
as	O
a	O
successor	O
to	O
the	O
Ceph	O
Community	O
Advisory	O
Board	O
.	O
</s>
<s>
Founding	O
members	O
of	O
the	O
Ceph	O
Foundation	O
included	O
Amihan	O
,	O
Canonical	O
,	O
China	O
Mobile	O
,	O
DigitalOcean	B-Application
,	O
Intel	O
,	O
OVH	B-General_Concept
,	O
ProphetStor	O
Data	O
Services	O
,	O
Red	O
Hat	O
,	O
SoftIron	O
,	O
SUSE	O
,	O
Western	O
Digital	O
,	O
XSKY	O
Data	O
Technology	O
,	O
and	O
ZTE	O
.	O
</s>
<s>
In	O
March	O
2021	O
,	O
SUSE	O
discontinued	O
its	O
Enterprise	O
Storage	B-General_Concept
product	O
incorporating	O
Ceph	O
in	O
favor	O
of	O
Longhorn	O
.	O
</s>
<s>
and	O
the	O
former	O
Enterprise	O
Storage	B-General_Concept
website	O
was	O
updated	O
stating	O
"	O
SUSE	O
has	O
refocused	O
the	O
storage	B-General_Concept
efforts	O
around	O
serving	O
our	O
strategic	O
SUSE	O
Enterprise	O
Storage	B-General_Concept
Customers	O
and	O
are	O
no	O
longer	O
actively	O
selling	O
SUSE	O
Enterprise	O
Storage.	O
"	O
</s>
<s>
The	O
name	O
(	O
emphasized	O
by	O
the	O
logo	O
)	O
suggests	O
the	O
highly	O
parallel	O
behavior	O
of	O
an	O
octopus	O
and	O
was	O
chosen	O
to	O
associate	O
the	O
file	B-Application
system	I-Application
with	O
"	O
Sammy	O
"	O
,	O
the	O
banana	O
slug	O
mascot	O
of	O
UCSC	O
.	O
</s>
