<s>
DG/UX	B-Operating_System
is	O
a	O
discontinued	O
Unix	B-Application
operating	I-Application
system	I-Application
developed	O
by	O
Data	O
General	O
for	O
its	O
Eclipse	B-Device
MV	I-Device
minicomputer	B-Architecture
line	O
,	O
and	O
later	O
the	O
AViiON	B-Device
workstation	B-Device
and	O
server	B-Application
line	O
(	O
both	O
Motorola	B-Architecture
88000	I-Architecture
and	O
Intel	O
IA-32-based	O
variants	O
)	O
.	O
</s>
<s>
DG/UX	B-Operating_System
1.00	O
,	O
released	O
in	O
March	O
,	O
1985	O
,	O
was	O
based	O
on	O
UNIX	B-Operating_System
System	I-Operating_System
V	I-Operating_System
Release	O
2	O
with	O
additions	O
from	O
4.1BSD	B-Operating_System
.	O
</s>
<s>
By	O
1987	O
,	O
DG/UX	B-Operating_System
3.10	O
had	O
been	O
released	O
,	O
with	O
4.2BSD	O
TCP/IP	B-Protocol
networking	O
,	O
NFS	B-Protocol
and	O
the	O
X	B-Operating_System
Window	I-Operating_System
System	I-Operating_System
included	O
.	O
</s>
<s>
DG/UX	B-Operating_System
4.00	O
,	O
in	O
1988	O
,	O
was	O
a	O
comprehensive	O
re-design	O
of	O
the	O
system	O
,	O
based	O
on	O
System	B-Operating_System
V	I-Operating_System
Release	I-Operating_System
3	I-Operating_System
,	O
and	O
supporting	O
symmetric	O
multiprocessing	B-Operating_System
on	O
the	O
Eclipse	B-Device
MV	I-Device
.	O
</s>
<s>
DG/UX	B-Operating_System
5.4	O
,	O
released	O
around	O
1991	O
,	O
replaced	O
the	O
legacy	O
Unix	B-Application
file	O
buffer	O
cache	O
with	O
unified	O
,	O
demand	O
paged	O
virtual	O
memory	O
management	O
.	O
</s>
<s>
Later	O
versions	O
were	O
based	O
on	O
System	B-Operating_System
V	I-Operating_System
Release	O
4	O
.	O
</s>
<s>
On	O
the	O
AViiON	B-Device
,	O
DG/UX	B-Operating_System
supported	O
multiprocessor	B-Operating_System
machines	O
at	O
a	O
time	O
when	O
most	O
variants	O
of	O
Unix	B-Application
did	O
not	O
.	O
</s>
<s>
The	O
operating	B-General_Concept
system	I-General_Concept
was	O
also	O
more	O
complete	O
than	O
some	O
other	O
Unix	B-Application
variants	O
;	O
for	O
example	O
,	O
the	O
operating	B-General_Concept
system	I-General_Concept
included	O
a	O
full	O
C	B-Language
compiler	O
(	O
gcc	B-Application
)	O
and	O
also	O
a	O
logical	B-Application
volume	I-Application
manager	I-Application
.	O
</s>
<s>
For	O
example	O
,	O
a	O
six-way	O
Pentium	O
Pro-based	O
AViiON	B-Device
would	O
support	O
several	O
hundred	O
users	O
using	O
text	O
terminals	O
.	O
</s>
<s>
The	O
volume	B-Application
manager	I-Application
built	O
into	O
the	O
OS	O
was	O
simple	O
,	O
but	O
very	O
powerful	O
.	O
</s>
<s>
DG/UX	B-Operating_System
5.4	O
supported	O
filesystem	O
shrinking	O
,	O
"	O
split	O
mirror	O
"	O
online	O
backup	O
,	O
filesystems	O
up	O
to	O
2	O
TB	O
,	O
and	O
filesystem	O
journaling	O
in	O
1991	O
.	O
</s>
<s>
DG/UX	B-Operating_System
had	O
a	O
high-performance	O
and	O
stable	O
clustered	O
filesystem	O
.	O
</s>
<s>
The	O
Clariion	B-Operating_System
storage	O
nas	O
was	O
connected	O
by	O
high-voltage	O
scsi	B-Architecture
controllers	O
,	O
and	O
scsi-hubs	O
.	O
</s>
<s>
Each	O
server	B-Application
had	O
double	O
scsi-controllers	O
for	O
failover	O
reasons	O
.	O
</s>
<s>
Both	O
controllers	O
where	O
master	O
on	O
the	O
same	O
bus	O
,	O
at	O
the	O
same	O
time	O
these	O
filesystems	O
where	O
NFS-mounted	O
form	O
the	O
cluster-master	O
'	O
s	O
floating	O
ip	O
.	O
</s>
<s>
The	O
data	O
was	O
written	O
from	O
each	O
cluster	O
node	O
directly	O
by	O
the	O
scsi	B-Architecture
bus	O
,	O
but	O
the	O
orchestration	O
,	O
the	O
i-node	O
tables	O
,	O
where	O
written	O
by	O
the	O
NFS-mount	O
from	O
each	O
cluster	O
members	O
.	O
</s>
<s>
Later	O
versions	O
added	O
support	O
for	O
processor	B-Operating_System
and	I-Operating_System
memory	I-Operating_System
affinity	I-Operating_System
to	O
support	O
their	O
high-end	O
multiprocessor	B-Operating_System
NUMA	B-Operating_System
AViiON	B-Device
system	O
.	O
</s>
