Cabling
the
storage
expansion
enclosures
in
a
redundant
loop
If
you
are
attaching
a
loop
of
storage
expansion
enclosures
to
your
storage
server,
you
should
cable
the
units
together
before
connecting
the
loop
to
the
storage
server.
Note:
If
you
are
attaching
only
a
single
storage
expansion
enclosure
to
the
storage
server,
you
do
not
need
to
review
this
section.
Continue
instead
with
Storage
expansion
enclosure
loop
redundancy
Both
the
DS4000
EXP700
and
DS4000
EXP710
provide
redundant
loop
support
when
the
second
ESM
is
configured,
and
when
both
loops
(called
A
and
B)
are
connected
to
a
storage
server
that
supports
redundant
loops.
shows
a
redundant
loop.
If
an
ESM,
cable,
or
SFP
module
fails
on
drive
loop
A,
drive
loop
B
provides
redundancy,
which
is
an
alternate
path
to
your
disk
drives.
IBM
fibre
channel
disk
drives
are
dual-ported,
providing
individual
access
from
two
fibre
channel
loops
to
the
same
disk
drive.
When
configuring
the
ESMs,
configure
the
second
ESM
the
same
way
you
configured
the
first
ESM.
Refer
to
the
Fibre
Channel
Cabling
Instructions
that
come
with
your
storage
server
for
more
information
about
dual-loop
support
and
implementation.
Each
ESM
has
an
SFP
module
input
port
and
an
SFP
module
output
port.
As
you
cable
storage
expansion
enclosures
together,
connecting
input
ports
to
output
ports
can
improve
diagnostic
capability
by
decreasing
the
risk
of
making
fibre
channel
cabling
errors
and
simplifying
troubleshooting
procedures
(because
cabling
connections
are
more
easily
identified).
Refer
to
your
storage
server
documentation
and
the
Fibre
Channel
Cabling
Instructions
for
cabling
connections
between
input
and
output
ports.
Loop A Fibre Channel
interface cable
Input
Output
Output
New storage
expansion enclosure
First storage
expansion enclosure
Storage server
with two RAID controllers
Left ESM board
Right ESM board
e
xp70023
Figure
40.
Redundant
loop
configuration
Chapter
2.
Installing
and
cabling
the
storage
expansion
enclosure
53
Summary of Contents for TotalStorage FAStT EXP700
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