<s>
Synnefo	B-General_Concept
is	O
a	O
complete	O
open-source	B-Application
cloud	B-Architecture
stack	O
written	O
in	O
Python	B-Language
that	O
provides	O
Compute	O
,	O
Network	O
,	O
Image	O
,	O
Volume	O
and	O
Storage	O
services	O
,	O
similar	O
to	O
the	O
ones	O
offered	O
by	O
AWS	B-Application
.	O
</s>
<s>
Synnefo	B-General_Concept
manages	O
multiple	O
Google	B-Language
Ganeti	I-Language
clusters	O
at	O
the	O
backend	B-Architecture
that	O
handle	O
low-level	O
VM	B-Architecture
operations	O
and	O
uses	O
Archipelago	O
to	O
unify	O
cloud	B-Architecture
storage	O
.	O
</s>
<s>
To	O
boost	O
3rd-party	O
compatibility	O
,	O
Synnefo	B-General_Concept
exposes	O
the	O
OpenStack	B-Application
APIs	O
to	O
users	O
.	O
</s>
<s>
Synnefo	B-General_Concept
is	O
being	O
developed	O
by	O
GRNET	O
(	O
Greek	O
Research	O
and	O
Technology	O
Network	O
)	O
,	O
and	O
is	O
powering	O
two	O
of	O
its	O
public	O
cloud	B-Architecture
services	I-Architecture
,	O
the	O
service	O
,	O
which	O
is	O
aimed	O
towards	O
the	O
Greek	O
academic	O
community	O
,	O
and	O
the	O
service	O
,	O
which	O
is	O
open	O
for	O
all	O
members	O
of	O
the	O
GÉANT	O
network	O
.	O
</s>
<s>
In	O
November	O
2006	O
,	O
in	O
an	O
effort	O
to	O
provide	O
advanced	O
cloud	B-Architecture
services	I-Architecture
for	O
the	O
Greek	O
academic	O
and	O
research	O
community	O
,	O
GRNET	O
decides	O
to	O
launch	O
a	O
cloud	B-Application
storage	I-Application
service	I-Application
,	O
similar	O
to	O
Amazon	B-General_Concept
's	I-General_Concept
S3	I-General_Concept
,	O
called	O
Pithos	O
.	O
</s>
<s>
In	O
June	O
2010	O
,	O
GRNET	O
decides	O
the	O
next	O
step	O
in	O
this	O
course	O
;	O
to	O
create	O
a	O
complete	O
,	O
AWS-like	O
cloud	B-Architecture
service	I-Architecture
(	O
Compute/Network/Volume/Image/Storage	O
)	O
.	O
</s>
<s>
Given	O
the	O
non-ephemeral	O
nature	O
of	O
the	O
resources	O
that	O
the	O
service	O
provides	O
,	O
the	O
need	O
arises	O
for	O
persistent	O
cloud	B-Architecture
servers	O
.	O
</s>
<s>
In	O
search	O
for	O
a	O
solution	O
,	O
in	O
October	O
2010	O
GRNET	O
decides	O
to	O
base	O
the	O
service	O
on	O
Google	B-Language
Ganeti	I-Language
and	O
to	O
design	O
and	O
implement	O
all	O
missing	O
parts	O
in-house	O
.	O
</s>
<s>
Around	O
this	O
point	O
,	O
in	O
April	O
2012	O
,	O
the	O
~	O
okeanos	O
team	O
decides	O
to	O
refer	O
to	O
the	O
whole	O
software	O
stack	O
as	O
Synnefo	B-General_Concept
and	O
starts	O
writing	O
the	O
first	O
version	O
of	O
the	O
Synnefo	B-General_Concept
documentation	O
.	O
</s>
<s>
In	O
December	O
2012	O
,	O
due	O
to	O
interest	O
from	O
other	O
parties	O
to	O
the	O
Synnefo	B-General_Concept
stack	O
,	O
GRNET	O
decides	O
to	O
conceptually	O
separate	O
the	O
~	O
okeanos	O
and	O
Synnefo	B-General_Concept
projects	O
.	O
</s>
<s>
Synnefo	B-General_Concept
starts	O
to	O
become	O
a	O
branding-neutral	O
,	O
IaaS	O
cloud	B-Architecture
computing	I-Architecture
software	O
,	O
while	O
~	O
okeanos	O
becomes	O
its	O
real-world	O
application	O
,	O
an	O
IaaS	O
for	O
the	O
Greek	O
academic	O
and	O
research	O
community	O
.	O
</s>
<s>
In	O
April	O
2013	O
,	O
a	O
new	O
Synnefo	B-General_Concept
version	O
(	O
v.013	O
)	O
gets	O
released	O
after	O
a	O
huge	O
cleanup	O
and	O
code	O
refactoring	O
.	O
</s>
<s>
All	O
separate	O
components	O
are	O
merged	O
under	O
the	O
single	O
Synnefo	B-General_Concept
repository	O
.	O
</s>
<s>
In	O
Jun	O
2013	O
,	O
Synnefo	B-General_Concept
v0.14	O
gets	O
released	O
.	O
</s>
<s>
Since	O
this	O
version	O
,	O
Synnefo	B-General_Concept
is	O
branding	O
neutral	O
(	O
all	O
remaining	O
~	O
okeanos	O
references	O
are	O
removed	O
)	O
.	O
</s>
<s>
Synnefo	B-General_Concept
is	O
modular	O
in	O
nature	O
and	O
consists	O
of	O
the	O
following	O
components	O
:	O
</s>
<s>
Astakos	O
is	O
the	O
Identity	O
management	O
component	O
which	O
provides	O
a	O
common	O
user	O
base	O
to	O
the	O
rest	O
of	O
Synnefo	B-General_Concept
.	O
</s>
<s>
Pithos	O
is	O
the	O
Object/File	O
Storage	O
component	O
of	O
Synnefo	B-General_Concept
.	O
</s>
<s>
It	O
is	O
a	O
thin	O
layer	O
mapping	O
user-files	O
to	O
content-addressable	O
blocks	O
which	O
are	O
then	O
stored	O
on	O
a	O
storage	O
backend	B-Architecture
.	O
</s>
<s>
Pithos	O
runs	O
at	O
the	O
cloud	B-Architecture
layer	O
and	O
exposes	O
the	O
OpenStack	B-Application
Object	O
Storage	O
API	O
to	O
the	O
outside	O
world	O
,	O
with	O
custom	O
extensions	O
for	O
syncing	O
.	O
</s>
<s>
Any	O
client	O
speaking	O
to	O
OpenStack	B-Application
Swift	O
can	O
also	O
be	O
used	O
to	O
store	O
objects	O
in	O
a	O
Pithos	O
deployment	O
.	O
</s>
<s>
The	O
process	O
of	O
mapping	O
user	O
files	O
to	O
hashed	O
objects	O
is	O
independent	O
from	O
the	O
actual	O
storage	O
backend	B-Architecture
,	O
which	O
is	O
selectable	O
by	O
the	O
administrator	O
using	O
pluggable	O
drivers	O
.	O
</s>
<s>
Currently	O
,	O
Pithos	O
has	O
drivers	O
for	O
two	O
storage	O
backends	B-Architecture
:	O
</s>
<s>
Whatever	O
the	O
storage	O
backend	B-Architecture
,	O
it	O
is	O
responsible	O
for	O
storing	O
objects	O
reliably	O
,	O
without	O
any	O
connection	O
to	O
the	O
cloud	B-Architecture
APIs	O
or	O
to	O
the	O
hashing	O
operations	O
.	O
</s>
<s>
Cyclades	O
is	O
the	O
Synnefo	B-General_Concept
component	O
that	O
implements	O
the	O
Compute	O
,	O
Network	O
,	O
Image	O
and	O
Volume	O
services	O
.	O
</s>
<s>
It	O
exposes	O
the	O
associated	O
OpenStack	B-Application
REST	O
APIs	O
:	O
OpenStack	B-Application
Compute	O
,	O
Network	O
,	O
Glance	O
and	O
soon	O
also	O
Cinder	O
.	O
</s>
<s>
Cyclades	O
is	O
the	O
part	O
which	O
manages	O
multiple	O
Ganeti	B-Language
clusters	O
at	O
the	O
backend	B-Architecture
.	O
</s>
<s>
Cyclades	O
issues	O
commands	O
to	O
a	O
Ganeti	B-Language
cluster	O
using	O
Ganeti	B-Language
's	O
Remote	O
API	O
(	O
RAPI	O
)	O
.	O
</s>
<s>
The	O
administrator	O
can	O
expand	O
the	O
infrastructure	O
dynamically	O
by	O
adding	O
new	O
Ganeti	B-Language
clusters	O
to	O
reach	O
datacenter	O
scale	O
.	O
</s>
<s>
Cyclades	O
knows	O
nothing	O
about	O
low-level	O
VM	B-Architecture
management	O
operations	O
,	O
e.g.	O
,	O
handling	O
of	O
VM	B-Architecture
creations	O
,	O
migrations	O
among	O
physical	O
nodes	O
,	O
and	O
handling	O
of	O
node	O
downtimes	O
;	O
the	O
design	O
and	O
implementation	O
of	O
the	O
end-user	O
API	O
is	O
orthogonal	O
to	O
VM	B-Architecture
handling	O
at	O
the	O
backend	B-Architecture
.	O
</s>
<s>
There	O
are	O
two	O
distinct	O
,	O
asynchronous	O
paths	O
in	O
the	O
interaction	O
between	O
Synnefo	B-General_Concept
and	O
Ganeti	B-Language
.	O
</s>
<s>
The	O
effect	O
path	O
is	O
activated	O
in	O
response	O
to	O
a	O
user	O
request	O
;	O
Cyclades	O
issues	O
VM	B-Architecture
control	O
commands	O
to	O
Ganeti	B-Language
over	O
RAPI	O
.	O
</s>
<s>
The	O
update	O
path	O
is	O
triggered	O
whenever	O
the	O
state	O
of	O
a	O
VM	B-Architecture
changes	O
,	O
due	O
to	O
Synnefo	B-General_Concept
-	O
or	O
administrator-initiated	O
actions	O
happening	O
at	O
the	O
Ganeti	B-Language
level	O
.	O
</s>
<s>
In	O
the	O
update	O
path	O
,	O
we	O
monitor	O
Ganeti	B-Language
's	O
job	O
queue	O
to	O
produce	O
notifications	O
to	O
the	O
rest	O
of	O
the	O
Synnefo	B-General_Concept
infrastructure	O
over	O
a	O
message	O
queue	O
.	O
</s>
<s>
The	O
REST	O
API	O
for	O
VM	B-Architecture
management	O
,	O
being	O
OpenStack	B-Application
compatible	O
,	O
can	O
interoperate	O
with	O
3rd	O
party	O
tools	O
and	O
client	O
libraries	O
.	O
</s>
<s>
The	O
networking	O
functionality	O
includes	O
dual	O
IPv4/IPv6	O
connectivity	O
for	O
each	O
VM	B-Architecture
,	O
easy	O
,	O
platform-provided	O
firewalling	O
either	O
through	O
an	O
array	O
of	O
pre-configured	O
firewall	O
profiles	O
,	O
or	O
through	O
a	O
roll-your-own	O
firewall	O
inside	O
the	O
VM	B-Architecture
.	O
</s>
<s>
The	O
networking	O
functionality	O
is	O
exported	O
all	O
the	O
way	O
from	O
the	O
backend	B-Architecture
to	O
the	O
API	O
and	O
the	O
UI	O
.	O
</s>
