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Active Memory
Active Memory is an IBM technology that improves the reliability of the DIMMs
through memory mirroring, memory scrubbing, and Memory ProteXion
The following notes describe the Active Memory features:
v Memory mirroring enables you to improve the reliability of the memory in your
v Memory scrubbing is an automatic daily test of all the system memory that
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IBM System x3850 Type 8863, 7362: Problem Determination and Service Guide
server by creating a mirror of the data in memory port 1 and storing it in memory
port 2.
Note: For memory mirroring to work, you must have DIMMs of the same size
and clock speed in both memory ports.
Complete the following steps to enable memory mirroring:
1. Check your operating system documentation to make sure that it supports
memory mirroring.
2. Install DIMMs of the same size and clock speed in the two memory ports.
3. Enable memory mirroring in the Configuration/Setup Utility program:
a. Turn on the server and watch the monitor screen.
b. When the message Press F1 for Configuration/Setup appears, press
F1.
c. From the Configuration/Setup Utility main menu, select Advanced Setup.
d. Select Memory Settings.
e. Select Memory Mirroring Settings.
f. Enable the memory mirroring setting from within this window.
g. Save and exit the Configuration/Setup Utility program.
When memory mirroring is enabled, the data that is written to memory is stored
in two locations. One copy is kept in the memory port 1 DIMMs, while a second
copy is kept in the memory port 2 DIMMs. During the execution of the read
command, the data is read from the DIMM with the least number of reported
memory errors through Memory scrubbing, which is enabled with memory
mirroring.
If memory scrubbing determines that a DIMM is damaged beyond use, read and
write operations are redirected to the remaining good DIMMs. Memory scrubbing
then reports the damaged DIMM and the Light Path Diagnostics feature displays
the error. After the damaged DIMM is replaced, memory mirroring then copies the
mirrored data back into the new DIMM.
detects and reports memory errors that might be developing before they cause a
server outage.
Note: Memory scrubbing and Memory ProteXion technology work with each
other and do not require memory mirroring to be enabled to work.
When an error is detected, memory scrubbing determines whether the error is
recoverable. If it is recoverable, Memory ProteXion is enabled and the data that
was stored in the damaged locations is rewritten to a new location. The error is
then reported so that preventive maintenance can be performed. Provided that
there are enough good locations to enable the correct operation of the server, no
further action is taken other than recording the error in the error logs.
If the error is not recoverable, memory scrubbing sends an error message to the
Light Path Diagnostics feature, which then lights the applicable LEDs to guide
you to the damaged DIMM. If memory mirroring is enabled, the mirrored copy of
the data in the mirrored DIMM is used to refresh the new DIMM after it is
installed.
™
features.
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