<s>
The	O
Symmetrix	B-Device
system	O
was	O
an	O
EMC	O
's	O
enterprise	B-General_Concept
storage	I-General_Concept
array	B-General_Concept
.	O
</s>
<s>
It	O
combined	O
dozens	O
of	O
hard	B-Device
drives	I-Device
into	O
a	O
single	O
virtual	O
device	O
that	O
was	O
then	O
shared	O
on	O
a	O
local	B-General_Concept
area	I-General_Concept
network	I-General_Concept
.	O
</s>
<s>
Symmetrix	B-Device
arrays	O
,	O
EMC	O
's	O
flagship	O
product	O
at	O
that	O
time	O
,	O
began	O
shipping	O
in	O
1990	O
as	O
a	O
storage	B-General_Concept
array	I-General_Concept
connected	O
to	O
an	O
IBM	B-Device
mainframe	I-Device
via	O
the	O
block	O
multiplexer	O
channel	O
.	O
</s>
<s>
Newer	O
generations	O
of	O
Symmetrix	B-Device
brought	O
additional	O
host	O
connection	O
protocols	O
which	O
include	O
ESCON	B-Device
,	O
SCSI	B-Architecture
,	O
Fibre	O
Channel-based	O
storage	O
area	O
networks	O
(	O
SANs	O
)	O
,	O
FICON	B-Architecture
and	O
iSCSI	B-Protocol
.	O
</s>
<s>
The	O
Symmetrix	B-Device
product	O
was	O
initially	O
popular	O
within	O
the	O
airline	O
industry	O
and	O
with	O
companies	O
that	O
were	O
willing	O
to	O
deviate	O
from	O
the	O
safety	O
of	O
IBM	O
's	O
3390	O
disk	B-Device
subsystem	I-Device
and	O
take	O
a	O
risk	O
with	O
the	O
unproven	O
Symmetrix	B-Device
array	B-General_Concept
.	O
</s>
<s>
Moshe	O
Yanai	O
managed	O
the	O
Symmetrix	B-Device
development	O
from	O
the	O
product	O
's	O
inception	O
in	O
1987	O
until	O
shortly	O
before	O
leaving	O
EMC	O
in	O
2001	O
,	O
and	O
his	O
Symmetrix	B-Device
development	O
team	O
grew	O
from	O
several	O
people	O
to	O
thousands	O
.	O
</s>
<s>
EMC	B-Device
Symmetrix	I-Device
VMAX	O
systems	O
are	O
storage	O
platforms	O
intended	O
for	O
open	O
systems	O
and	O
mainframe	O
computing	O
.	O
</s>
<s>
Symmetrix	B-Device
VMAX	O
systems	O
run	O
the	O
Enginuity	O
operating	O
environment	O
.	O
</s>
<s>
The	O
Direct	O
Matrix	O
Architecture	O
(	O
DMX	B-Device
)	O
product	O
line	O
with	O
models	O
DMX800	O
,	O
DMX1000	O
and	O
DMX2000	O
were	O
announced	O
in	O
February	O
2003	O
.	O
</s>
<s>
The	O
system	O
scales	O
from	O
a	O
single	O
Symmetrix	B-Device
VMAX	O
Engine	O
system	O
with	O
one	O
storage	O
bay	O
to	O
a	O
large	O
eight-engine	O
system	O
with	O
a	O
maximum	O
of	O
ten	O
storage	O
bays	O
.	O
</s>
<s>
The	O
Symmetrix	B-Device
VMAX	O
system	O
bay	O
can	O
hold	O
one	O
to	O
eight	O
engines	O
.	O
</s>
<s>
The	O
VMAX	O
has	O
one	O
to	O
ten	O
storage	O
bays	O
for	O
hard	B-Device
drives	I-Device
.	O
</s>
<s>
Each	O
storage	O
bay	O
contains	O
16	O
Disk	B-General_Concept
Array	I-General_Concept
Enclosures	O
(	O
DAE	O
)	O
.	O
</s>
<s>
Each	O
DAE	O
contains	O
15-25	O
hard	B-Device
drives	I-Device
.	O
</s>
<s>
VMAX	O
supports	O
SATA	O
,	O
Fiber	B-Architecture
Channel	I-Architecture
,	O
SAS	O
and	O
Solid	O
State	O
drives	O
.	O
</s>
<s>
The	O
Symmetrix	B-Device
Remote	I-Device
Data	I-Device
Facility	I-Device
(	O
SRDF	B-Device
)	O
is	O
a	O
family	O
of	O
software	O
products	O
that	O
facilitates	O
the	O
data	B-Architecture
replication	I-Architecture
from	O
one	O
Symmetrix	B-Device
storage	B-General_Concept
array	I-General_Concept
to	O
another	O
through	O
a	O
storage	O
area	O
network	O
or	O
Internet	B-Protocol
Protocol	I-Protocol
(	O
IP	O
)	O
network	O
.	O
</s>
<s>
SRDF	B-Device
logically	O
pairs	O
a	O
device	O
or	O
a	O
group	O
of	O
devices	O
from	O
each	O
array	B-General_Concept
and	O
replicates	O
data	O
from	O
one	O
to	O
the	O
other	O
synchronously	O
or	O
asynchronously	O
.	O
</s>
<s>
In	O
synchronous	O
mode	O
(	O
SRDF/S	O
)	O
,	O
the	O
primary	O
array	B-General_Concept
waits	O
until	O
the	O
secondary	O
array	B-General_Concept
has	O
acknowledged	O
each	O
write	O
before	O
the	O
next	O
write	O
is	O
accepted	O
,	O
ensuring	O
that	O
the	O
replicated	O
copy	O
of	O
the	O
data	O
is	O
always	O
as	O
current	O
as	O
the	O
primary	O
.	O
</s>
<s>
Asynchronous	O
SRDF	B-Device
(	O
SRDF/A	O
)	O
transfers	O
changes	O
made	O
to	O
the	O
secondary	O
array	B-General_Concept
in	O
units	O
called	O
delta	O
sets	O
,	O
which	O
are	O
transferred	O
at	O
defined	O
intervals	O
.	O
</s>
<s>
Other	O
forms	O
of	O
SRDF	B-Device
integrate	O
with	O
clustered	O
environments	O
and	O
to	O
manage	O
multiple	O
SRDF	B-Device
pairs	O
where	O
replication	B-Architecture
of	O
multiple	O
devices	O
must	O
be	O
consistent	O
(	O
such	O
as	O
with	O
the	O
data	O
files	O
and	O
log	O
files	O
of	O
a	O
database	O
application	O
)	O
.	O
</s>
