Users Guide

Boot
Server BIOS restores NVDIMM-N DRAM data from its onboard Flash during boot time. BIOS verifies that the NVDIMM-N
Battery is installed and has sufficient charge for a Save event in case of an power loss. BIOS also verifies that the installed
server Power Supplies are sufficiently sized for the server configuration. This is to ensure that after an power loss, the PSUs are
able to provide enough power to hold up the server until Battery power takes over. Once BIOS verifies that both the Battery
and PSUs have enough power to support NVDIMM-Ns, BIOS arms the NVDIMM-Ns and allows the server to boot to OS.
If BIOS detects any issues, BIOS will display an F1/F2 error message on screen and lock the NVDIMM-N in Read-Only mode.
OSes will still be able to read NVDIMM-N data at this time, but any changes will be discarded. To restore the NVDIMM-N to
normal operation, the user must correct the issue and reboot the server. Please refer to Section BIOS Error Messages 4.2 BIOS
Error Messages for more details.
Automatic Shutdown and Save
A primary goal for DellEMC’s NVDIMM-N Persistent Memory Solution is to protect customer data. A key ingredient in the data
protection is the server’s Power Supply. The PSU(s) must have sufficient hold-up power for the Save process to start and for
the server to transition to the NVDIMM-N Backup Battery.
Any changes to the server hardware configuration due to hot add/remove of devices or PSU failures will result in a server
power budget re-evaluation. If in the case where the power budget exceeds the PSU’s ability to hold-up power, the server will
immediately shutdown to trigger a Save on the NVDIMM-N and protect customer data to flash. The server will reboot. If the
problem persists, BIOS will place the NVDIMM-N into Read-Only mode before booting to the OS.
In a modular chassis, since power is managed at the chassis level, an power loss event or removal of PSUs resulting in power
demand exceeding available capacity will trigger an entire chassis shutdown if there are NVDIMM equipped sleds installed and
powered on. If the chassis is power constrained, additional components will not be allowed to turn on if the power requirements
of those components will push the power consumption of the chassis above the available power. Additionally, if a user elects to
perform a "Virtual Reseat" of an NVDIMM equipped sled, the targeted sled will trigger a save on the NVDIMM-N, but not affect
the whole chassis.
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Server Behavior with NVDIMM-Ns