Front-End Connectivity Modes
Dell Compellent
99
Legacy Mode
Legacy
mode
provides
controller
redundancy
for
a
dual
‐
controller
Storage
Center
by
connecting
multiple
primary
and
reserved
ports
to
each
Fibre
Channel
or
Ethernet
switch.
In
legacy
mode,
each
primary
port
on
a
controller
is
paired
with
a
corresponding
reserved
port
on
the
other
controller.
During
normal
conditions,
the
primary
ports
process
IO
and
the
reserved
ports
are
in
standby
mode.
If
a
controller
fails,
the
primary
ports
fail
over
to
the
corresponding
reserved
ports
on
the
other
controller.
This
approach
ensures
that
servers
connected
to
the
switch
do
not
lose
connectivity
if
one
of
the
controllers
fails.
For
optimal
performance,
the
primary
ports
should
be
evenly
distributed
across
both
controllers.
When
possible,
front
‐
end
connections
should
be
made
to
separate
controller
IO
cards
to
improve
redundancy.
Fault Domains in Legacy Mode
Each
pair
of
primary
and
reserved
ports
is
grouped
into
a
fault
domain
in
the
Storage
Center
software.
The
fault
domain
determines
which
ports
are
allowed
to
fail
over
to
each
other.
The
following
requirements
apply
to
fault
domains
in
legacy
mode
on
a
dual
‐
controller
Storage
Center:
A
fault
domain
must
contain
a
one
type
of
transport
media
(FC
or
iSCSI,
but
not
both).
A
fault
domain
must
contain
one
primary
port
and
one
reserved
port.
The
reserved
port
must
be
located
on
a
different
controller
than
the
primary
port.
Requirements for Legacy Mode
The
following
requirements
must
be
met
to
configure
a
Storage
Center
in
legacy
mode.
See Also
Note:
For
a
single
‐
controller
Storage
Center,
only
one
fault
domain
is
required
for
each
transport
type
(FC
or
iSCSI)
because
there
are
no
reserved
ports.
Requirement
Description
Controller
front
‐
end
ports
Each
controller
must
have
enough
front
‐
end
ports
to
connect
two
paths
to
each
Fibre
Channel
or
Ethernet
switch.
Multipathing
If
multiple
active
paths
are
available
to
a
server,
the
server
must
be
configured
for
MPIO
to
use
more
than
one
path
simultaneously.
Fibre
Channel
zoning
FC
switches
must
be
zoned
to
meet
the
legacy
mode
zoning
requirements.
