ESM
failover
architecture
This
section
provides
information
about
the
ESM
failover
architecture
for
the
EXP100,
including
guidelines
for
creating
array
configurations
that
offer
maximum
protection
of
data
access
in
the
event
of
ESM
failure.
Understanding
ESM
failover
architecture
With
full
high-availability
(FHA)
support,
the
EXP100
R2
or
R3
storage
expansion
enclosure
architecture
provides
full
drive
failover
and
fail-back
support
for
a
loss
of
connectivity
due
to
failed
components
in
the
drive
paths
(such
as
failed
SFPs,
Fibre
Channel
cables,
ESMs,
and
so
on).
In
normal
operation,
each
ESM
in
the
EXP100
chassis
manages
only
one-half
of
the
drives
in
the
EXP100
chassis
even
though
each
ESM
can
access
all
of
the
drives
as
shown
in
The
left
ESM
manages
drives
at
odd-numbered
slots
(1,
3,
5,
7,
9,
11,
13);
the
right
ESM
manages
drives
at
even-numbered
slots
(2,
4,
6,
8,
10,
12,
14).
Note:
In
contrast
to
the
EXP100
R2
and
R3
expansion
enclosures,
which
have
ESM
firmware
installed
that
supports
full
high-availability,
EXP100
R1
expansion
enclosures
have
low
high-availability
(LHA)
firmware
installed.
Therefore,
EXP100
R1
units
do
not
provide
SATA
hard
drive
failover
or
fail-back
support
for
a
loss
of
connectivity
due
to
bad
components
in
the
Fibre
Channel
drive
paths
to
the
ESM
(such
as
failed
SFPs
or
Fibre
Channel
cables).
They
also
do
not
provide
failover
or
fail-back
support
for
the
loss
of
an
ESM
that
is
in
a
failed/fault
state
or
that
is
removed
from
the
EXP100
expansion
enclosure
chassis.
In
this
case,
the
controller
displays
the
drive
1220 mm cold
aisle width
2440 mm between
center lines of hot
and cold aisle
Perforated tiles
or gratings
back
back
T42 racks
T42 racks
T42 racks
Cold aisle
Hot aisle
Air
conditioner
back
front
front
front
Airflow
Figure
8.
Example
of
cold
aisle/hot
aisle
rack
configuration
24
IBM
TotalStorage
DS4000
EXP100
Storage
Expansion
Enclosure:
Installation,
User’s
and
Maintenance
Guide
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Summary of Contents for TotalStorage EXP100
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