IBM 7979B1U User Manual - Page 84

online-spare

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Note: When only one pair of DIMMs is installed in the server and the BIOS code level is version 1.04 (GGE127A) or later, you can improve performance by installing the DIMMs in connectors 1 and 7 instead of 1 and 4. However, because the connectors in the pair are not on the same memory branch (see the following illustration), Chipkill memory protection is disabled. DIMM 12 DIMM 11 Channel 3 DIMM 10 Branch 1 DIMM 9 DIMM 8 DIMM 7 DIMM 6 DIMM 5 DIMM 4 DIMM 3 DIMM 2 DIMM 1 Channel 2 Channel 1 Branch 0 Channel 0 v Each DIMM in a pair must be the same size, speed, type, and technology to ensure that the server will operate correctly. v You can configure the server to use memory mirroring. Memory mirroring stores data in two pairs of DIMMs simultaneously. If a failure occurs, the memory controller switches from the active pair to the mirroring pair. See "Memory mirroring" on page 69 for more information about memory mirroring and the DIMM installation sequence that is required. v The server supports online-spare memory. This feature disables the failed memory from the system configuration and activates an online-spare pair of DIMMs to replace the failed active DIMM pair. See "Online-spare memory" on page 70 for more information about online-spare memory and the DIMM configuration that is required. v You can enable either online-spare memory or memory mirroring, but not both at the same time. Online-spare memory provides more memory capacity than mirroring. Mirroring provides better memory protection but less memory capacity than online-spare memory. v When you install or remove DIMMs, the server configuration information changes. When you restart the server, the system displays a message that indicates that the memory configuration has changed. 68 System x3650 Type 7979: User's Guide

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Note:
When
only
one
pair
of
DIMMs
is
installed
in
the
server
and
the
BIOS
code
level
is
version
1.04
(GGE127A)
or
later,
you
can
improve
performance
by
installing
the
DIMMs
in
connectors
1
and
7
instead
of
1
and
4.
However,
because
the
connectors
in
the
pair
are
not
on
the
same
memory
branch
(see
the
following
illustration),
Chipkill
memory
protection
is
disabled.
DIMM 1
DIMM 2
DIMM 3
DIMM 4
DIMM 5
DIMM 6
DIMM 7
DIMM 8
DIMM 9
Channel 0
Channel 1
Channel 2
DIMM 10
DIMM 11
DIMM 12
Channel 3
Branch 1
Branch 0
v
Each
DIMM
in
a
pair
must
be
the
same
size,
speed,
type,
and
technology
to
ensure
that
the
server
will
operate
correctly.
v
You
can
configure
the
server
to
use
memory
mirroring.
Memory
mirroring
stores
data
in
two
pairs
of
DIMMs
simultaneously.
If
a
failure
occurs,
the
memory
controller
switches
from
the
active
pair
to
the
mirroring
pair.
See
“Memory
mirroring”
on
page
69
for
more
information
about
memory
mirroring
and
the
DIMM
installation
sequence
that
is
required.
v
The
server
supports
online-spare
memory.
This
feature
disables
the
failed
memory
from
the
system
configuration
and
activates
an
online-spare
pair
of
DIMMs
to
replace
the
failed
active
DIMM
pair.
See
“Online-spare
memory”
on
page
70
for
more
information
about
online-spare
memory
and
the
DIMM
configuration
that
is
required.
v
You
can
enable
either
online-spare
memory
or
memory
mirroring,
but
not
both
at
the
same
time.
Online-spare
memory
provides
more
memory
capacity
than
mirroring.
Mirroring
provides
better
memory
protection
but
less
memory
capacity
than
online-spare
memory.
v
When
you
install
or
remove
DIMMs,
the
server
configuration
information
changes.
When
you
restart
the
server,
the
system
displays
a
message
that
indicates
that
the
memory
configuration
has
changed.
68
System
x3650
Type
7979:
User’s
Guide