Documenting a virtualization project

Experiences in Virtualization

Lesson Learned: memory management in new HP DL360/380

Posted by martijnl on July 31, 2009

Can’t say I should not have known this (because it’s in the quick specs of both servers) but the new DL360G6 and DL380G6 have different memory management than the previous generation.

This means that there are strict limitations on the amount and type of memory that you can use and there are strict guidelines for how much memory can be used in a server given a CPU/Memory combination.

From the Quick Specs document of the DL360 G6:

DDR3 memory population guidelines

Some DIMM installation guidelines are summarized below:

  • For servers with eighteen (18) memory slots:
    • There are three (3) channels per processor; six (6) channels per server
    • There are three (3) DIMM slots for each memory channel; eighteen (18) total slots
    • Memory channel 1 consists of the three (3) DIMMs that are closest to the processor
    • Memory channel 3 consists of the three (3) DIMMs that are furthest from the processor
  • DIMM slots that are white should be populated first
  • Do not mix Unbuffered memory (UDIMMs) with Registered memory (RDIMMs)
  • Do not install DIMMs if the corresponding processor is not installed
  • If only one processor is installed in a 2CPU system, only half of the DIMM slots are available
  • To maximize performance, balance the total memory capacity between all installed processors
  • It is not required, but it is recommended to load the channels similarly if possible
  • You can only have up to eight (8) ranks installed per channel
  • You can only install two quad-rank DIMMs per channel
  • You can only install two UDIMMs per channel; if available, the third slot in the channel must remain empty
  • Populate DIMMs from heaviest load (quad-rank) to lightest load (single-rank) within a channel
  • Heaviest load (DIMM with most ranks) within a channel goes furthest from the chipset
  • For memory mirroring mode, channel 3 must be unpopulated. Channels 1 and 2 are populated identically
  • For lock-step mode, channel 3 must be unpopulated. DIMMs in channels 1 and 2 will be installed in pairs. The paired slots will be 1,4; 2,5; 3;6 on a 3DPC system or 1,4; 2,5; on a 2DPC system
  • No mixing DIMM voltage; all DIMMs must be the same voltage

WW QuickSpecs for the 360 G6 are here: You can find the Quick Specs documents (US and WorldWide) from the server information pages on


4 Responses to “Lesson Learned: memory management in new HP DL360/380”

  1. […] a lessons learned article he warns about the new memory management in the new HP ProLiant DL360/380 […]

  2. Daniel said

    Good definition in your post here…are most of these not limitations in the Core i7 chipset/Numa architecture and not the G6 mainboard?


    • martijnl said

      I couldn’t say as I have only worked with HP lately. It’s just a heads up to read the quickspecs and be aware of the consequences before speccing out a Proliant Server.

  3. Denchy said

    Little tool from HP

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