<s>
Enterprise	B-Application
Storage	I-Application
OS	I-Application
,	O
also	O
known	O
as	O
ESOS	O
,	O
is	O
a	O
Linux	B-Application
distribution	I-Application
that	O
serves	O
as	O
a	O
block-level	O
storage	O
server	O
in	O
a	O
storage	O
area	O
network	O
(	O
SAN	O
)	O
.	O
</s>
<s>
ESOS	O
is	O
composed	O
of	O
open-source	B-Application
software	I-Application
projects	O
that	O
are	O
required	O
for	O
a	O
Linux	B-Application
distribution	I-Application
and	O
several	O
proprietary	O
build	O
and	O
install	O
time	O
options	O
.	O
</s>
<s>
The	O
SCST	B-Application
project	O
is	O
the	O
core	O
component	O
of	O
ESOS	O
;	O
it	O
provides	O
the	O
back-end	O
storage	O
functionality	O
.	O
</s>
<s>
ESOS	O
is	O
a	O
niche	O
Linux	B-Application
distribution	I-Application
.	O
</s>
<s>
ESOS	O
is	O
intended	O
to	O
run	O
on	O
a	O
USB	O
flash	O
drive	O
,	O
or	O
some	O
other	O
type	O
of	O
removable	O
media	O
such	O
as	O
Secure	B-Device
Digital	I-Device
,	O
CompactFlash	B-Device
,	O
etc	O
.	O
</s>
<s>
ESOS	O
is	O
a	O
memory	O
resident	O
operating	B-General_Concept
system	I-General_Concept
:	O
At	O
boot	O
,	O
a	O
tmpfs	B-Application
file	O
system	O
is	O
initialized	O
as	O
the	O
root	O
file	O
system	O
and	O
the	O
USB	O
flash	O
drive	O
image	O
is	O
copied	O
onto	O
this	O
file	O
system	O
.	O
</s>
<s>
ESOS	O
utilizes	O
a	O
text-based	B-Application
user	I-Application
interface	I-Application
(	O
TUI	O
)	O
for	O
system	O
management	O
,	O
network	O
configuration	O
,	O
and	O
storage	O
provisioning	O
functions	O
.	O
</s>
<s>
The	O
TUI	O
used	O
in	O
ESOS	O
is	O
written	O
in	O
C	B-Language
;	O
the	O
ncurses	B-Language
and	O
CDK	B-Device
libraries	O
are	O
used	O
.	O
</s>
<s>
These	O
core	O
functions	O
are	O
supported	O
by	O
SCST	B-Application
and	O
third-party	O
target	O
drivers	O
that	O
vendors	O
have	O
developed	O
for	O
SCST	B-Application
:	O
</s>
<s>
Fibre	B-Protocol
Channel	I-Protocol
over	I-Protocol
Ethernet	I-Protocol
(	O
FCoE	B-Protocol
)	O
:	O
A	O
software	O
target	O
implementation	O
supports	O
NICs	O
with	O
DCB/DCBX	O
capabilities	O
,	O
or	O
build	O
time	O
options	O
exist	O
for	O
supporting	O
Emulex	O
OneConnect	O
FCoE	B-Protocol
CNAs	O
(	O
requires	O
the	O
Emulex	O
OCS	O
SDK	O
)	O
and	O
Chelsio	O
Uwire	O
FCoE	B-Protocol
CNAs	O
.	O
</s>
<s>
iSCSI	B-Protocol
:	O
Will	O
work	O
over	O
any	O
IP	O
communication	O
method	O
supported	O
by	O
ESOS	O
(	O
Ethernet	O
,	O
IPoIB	O
)	O
.	O
</s>
<s>
Open-source	B-Application
software	I-Application
projects	O
and	O
commodity	B-Device
computing	I-Device
server	O
hardware	O
are	O
used	O
on	O
the	O
back-end	O
side	O
to	O
provide	O
the	O
underlying	O
storage	O
utilized	O
by	O
the	O
front-end	O
target	O
interfaces	O
:	O
</s>
<s>
Btrfs	B-Operating_System
,	O
XFS	B-Application
,	O
and	O
ext4	B-Application
are	O
all	O
supported	O
file	O
systems	O
for	O
virtual	O
disk	O
files	O
used	O
with	O
the	O
"	O
vdisk_fileio	O
"	O
device	O
handler	O
.	O
</s>
<s>
Popular	O
,	O
modern	O
hardware	O
RAID	B-Device
controllers	I-Device
from	O
LSI	O
,	O
Adaptec	O
,	O
HP	O
,	O
and	O
Areca	O
are	O
also	O
supported	O
in	O
ESOS	O
,	O
including	O
install-time	O
CLI	B-Application
tool	O
integration	O
for	O
these	O
adapters	O
.	O
</s>
<s>
Clustering	O
and	O
high-availability	O
support	O
is	O
made	O
possible	O
by	O
the	O
Pacemaker	B-Device
and	O
Corosync	B-Operating_System
cluster	O
software	O
stack	O
.	O
</s>
<s>
DRBD	B-Application
is	O
fully	O
supported	O
to	O
facilitate	O
replication	B-Architecture
between	O
ESOS	O
storage	O
servers	O
,	O
and/or	O
to	O
create	O
redundant	O
ESOS	O
storage	O
server	O
clusters	O
.	O
</s>
<s>
Virtual	B-Device
Tape	I-Device
Library	I-Device
(	O
VTL	O
)	O
support	O
by	O
the	O
mhVTL	O
project	O
.	O
</s>
<s>
Three	O
SSD	O
caching	O
solutions	O
:	O
EnhanceIO	B-Application
,	O
bcache	B-Application
,	O
and	O
dm-cache	B-Application
(	O
lvmcache	O
)	O
.	O
</s>
<s>
Other	O
block	O
storage	O
functions	O
include	O
the	O
automated	B-Application
tiered	I-Application
storage	I-Application
via	O
the	O
BTIER	O
project	O
and	O
Ceph	B-Operating_System
RBD	O
mapping	O
.	O
</s>
<s>
ESOS	O
differs	O
from	O
popular	O
Linux	B-Application
distributions	I-Application
in	O
that	O
there	O
is	O
no	O
bootable	O
ISO	B-General_Concept
image	I-General_Concept
provided	O
.	O
</s>
<s>
ESOS	O
consists	O
of	O
one	O
archive	O
file	O
that	O
is	O
extracted	O
on	O
a	O
local	O
computer	O
running	O
a	O
supported	O
operating	B-General_Concept
system	I-General_Concept
(	O
Linux	B-Application
,	O
Windows	O
,	O
or	O
Mac	O
OS	O
X	O
)	O
.	O
</s>
<s>
The	O
ESOS	O
installer	O
script	O
prompts	O
the	O
user	O
for	O
the	O
installation	O
target	O
device	O
,	O
writes	O
the	O
image	O
,	O
and	O
allow	O
users	O
to	O
integrate	O
proprietary	O
CLI	B-Application
RAID	B-Device
controller	I-Device
utilities	O
into	O
the	O
ESOS	O
USB	O
flash	O
drive	O
.	O
</s>
