Cache memory and raid controller battery, Cache memory, Cache – IBM Partner Pavilion DS4100 User Manual
Page 107: Memory, Raid, Controller, Battery, Power, Supply, Leds
Table
14.
Fan
LED
(continued)
LED
Color
Operating
states
1
1
Always
use
the
DS4000
Storage
Manager
client
to
identify
the
failure.
Table
15.
Power
supply
LEDs
LED
Color
Operating
states
1
Fault
Amber
v
Off
-
Normal
operation.
v
On
-
One
of
the
following
situations
has
occurred:
–
The
power
supply
has
failed.
–
An
over-temperature
condition
has
occurred.
Power
Green
v
On
-
Normal
operation.
v
Off
-
One
of
the
following
situations
has
occurred:
–
The
power
supply
is
disconnected.
–
The
power
supply
is
seated
incorrectly.
–
The
storage
server
has
no
power.
–
The
power
supply
is
turned
off.
1
Always
use
the
DS4000
Storage
Manager
client
to
identify
the
failure.
Cache
memory
and
RAID
controller
battery
Each
RAID
controller
in
the
DS4100
contains
128
MB
of
cache
data.
Each
controller
also
contains
a
rechargeable
battery
that
maintains
data
in
the
cache
in
the
event
of
a
power
failure.
The
following
sections
describe
these
features
and
their
associated
LEDs.
Cache
memory
Cache
memory
is
memory
on
the
RAID
controller
that
is
used
for
intermediate
storage
of
read
and
write
data
on
the
DS4100
base
storage
server
RAID
controllers.
Using
cache
memory
can
increase
system
performance.
The
data
for
a
read
operation
from
the
host
might
be
in
the
cache
memory
from
a
previous
operation
(thus
eliminating
the
need
to
access
the
drive
itself),
and
a
write
operation
is
completed
when
it
is
written
to
the
cache,
rather
than
to
the
drives.
Note:
In
the
DS4100
single-controller
storage
server,
the
RAID
controller
cache
memory
is
used
for
storing
read
data
only.
The
controller
firmware
ignores
a
write-cache
enabled
setting.
This
protects
data
in
the
event
of
a
controller
failure,
which
would
cause
the
cache
to
be
inaccessible.
See
the
DS4000
Storage
Manager
client
documentation
for
information
on
setting
cache
memory
options.
The
RAID
controller
has
a
Cache
active
LED
that
displays
the
current
status
of
the
cache.
The
LED
is
on
if
there
is
data
in
the
cache,
and
it
is
off
if
there
is
no
data
in
the
cache.
If
caching
is
enabled
and
the
Cache
active
LED
never
comes
on
during
I/O
activity,
it
indicates
that
the
cache
memory
has
failed
or
the
battery
has
failed
(the
green
Battery
LED
will
be
off).
Chapter
4.
Operating
the
storage
server
75