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Users Guide

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Server Behavior with NVDIMM-Ns
The server behavior changes slightly when NVDIMM-Ns are installed. This section covers differences that can be observed as
the server shuts down and boots up. This section will also describe scenarios where the server will automatically shutdown to
ensure that NVDIMM-N DRAM data is securely stored to flash.
Topics:
• Shutdown
• Boot
• Automatic Shutdown and Save
Shutdown
In order for NVDIMM-N data to persist across server power cycles, the NVDIMM-N must save its DRAM data to on boardflash.
The Save is triggered by events that would result in power loss to the NVDIMM-N. In MX7000, the entire chassis is shutdown
when there is a loss of power and at least one NVDIMM-N equipped server is powered on and armed when power loss occurs.
During the Save, the server maintains power to the NVDIMM-Ns, and a battery is used to provide back-up power in case of an
power loss. The server remains in a low-power reset state, and the power button on the server's front control panel blinks green
once per second to indicate that a save is in progress. The Save takes approximately 1 minute to complete with the 16GB
NVDIMM-N DIMMs (140 seconds for MX740c and MX840c servers).
Figure 17. R740 Control Panel
Once the Save completes, the server continues its normal power down sequencing. If the Power Button is pressed (to request
server power on) while a SAVE in progress, the server will queue the power-on to occur after the Save.
NOTE:
When NVDIMMs are installed, verify that the Server is completely powered down before attempting to perform any
service actions. This includes removing a server from a modular chassis after initiating a shutdown procedure. If a server
equipped with NVDIMMs is removed from a modular chassis prior to the save completing, the save will be interrupted and
data loss will occur. The server is completely powered down when all LEDs including NVDIMM-N and NVDIMM-N Battery
LEDs are off.
NOTE: If a Modular server supporting NVDIMM-N is powered on, the entire chassis will be shutdown when there is a full
loss of power or partial loss below minimum chassis power budget requirements.
Users cannot see these LEDs without removing the cover which they should not do during operation. User action is to wait until
the LED on front of the system stops blinking.
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Server Behavior with NVDIMM-Ns 29