Installing a DIMM

Use this information to install a DIMM. The upper and lower compute nodes each have their own dedicated DIMMs.

Before you install a DIMM, complete the following steps:
  1. Read Safety and Installation guidelines.
  2. Read the documentation that comes with the DIMMs.
  3. If the Flex System x222 Compute Node is installed in a chassis, remove it (see Removing a compute node from a chassis for instructions).
  4. Carefully lay the compute node on a flat, static-protective surface, orienting the compute node with the bezel pointing toward the left.

This component can be installed as an optional device or as a CRU. The installation procedure is the same for the optional device and the CRU.

After you install or remove a DIMM in the upper or lower compute node, you must change and save the new configuration information for that compute node by using the Setup utility. When you turn on the compute node where DIMMs have been installed or removed, a message indicates that the memory configuration has changed. Start the Setup utility and select Save Settings (see Using the Setup utility for more information) to save changes.

If you are installing a DIMM as a result of a DIMM failure, you might have to reenable the DIMM. To re-enable the DIMM, complete the following steps:
  1. Verify that the amount of installed memory is the expected amount of memory through the operating system in the upper or lower compute node where you installed the DIMM, by watching the monitor as the compute node starts, by using the CMM sol command, or through Flex System Manager management software (if installed).
  2. Run the Setup utility in the upper or lower compute node where you installed the DIMM to reenable the DIMMs (see Using the Setup utility for more information).

The upper and lower compute nodes each have a total of 12 dual inline memory module (DIMM) connectors. The compute node supports low-profile (LP) DDR3 DIMMs with error-correcting code (ECC) in 4 GB, 8 GB, 16 GB, and 32 GB capacities.

The following illustration shows the DIMM connectors, in the lower compute node.


Graphic illustrating the lower system-board connectors

The following illustration shows the DIMM connectors, in the upper compute node.


Graphic illustrating the upper system board connectors

The memory is accessed internally through six channels, with three channels for each microprocessor. Each channel contains two DIMM connectors. Each channel can have one, two, or four ranks. The following tables list each channel for the upper and lower system boards and show which DIMM connectors are in the channel. Memory channel configuration for the upper and lower system boards is the same.

Table 1. Memory-channel configuration.

Three column table that contains each channel for the upper and lower system boards and show which DIMM connectors are in the channel
Microprocessor Memory channel DIMM connectors
Microprocessor 1 Channel A 6 and 5
Channel B 4 and 3
Channel C 2 and 1
Microprocessor 2 Channel D 12 and 11
Channel E 8 and 7
Channel F 10 and 9

Depending on the memory mode that is set in the Setup utility, the compute node can support a minimum of 4 GB and a maximum of 384 GB of system memory in each compute node with one microprocessor. If two microprocessors are installed, each compute node can support a minimum of 8 GB and a maximum of 384 GB of system memory.

The following notes describe information that you must consider when you install memory:
  • You cannot mix RDIMMs and LRDIMMs in the same compute node.
  • A total of two ranks on each of the three memory channels is supported.
There are three memory modes. You can set the memory mode for each compute node using the Setup utility (System Settings > Memory > Memory Mode). See the memory settings for more information.
  • Independent-channel mode: Independent-channel mode provides a maximum of 192 GB of usable memory for each compute node with one installed microprocessor, and 384 GB of usable memory for each compute node with two installed microprocessors (using optional 32 GB DIMMs).
  • Rank-sparing mode: In rank-sparing mode, one memory DIMM rank serves as a spare of the other ranks on the same channel. The spare rank is held in reserve and is not used as active memory. The spare rank must have identical or larger memory capacity than all the other active DIMM ranks on the same channel. After an error threshold is surpassed, the contents of that rank is copied to the spare rank. The failed rank of DIMMs is taken offline, and the spare rank is put online and used as active memory in place of the failed rank.
    The following notes describe additional information that you must consider when you select rank-sparing memory mode:
    • Rank-sparing on one channel is independent of the sparing on all other channels.
    • You can use the Setup utility to determine the status of the DIMM ranks.
  • Mirrored-channel mode: In mirrored-channel mode, memory is installed in pairs. Each DIMM in a pair must be identical in size and architecture. The channels are grouped in pairs with each channel receiving the same data. One channel is used as a backup of the other, which provides redundancy. In mirrored-channel mode, only channels B and C are used, with the memory contents on channel B duplicated in channel C (channel A is not used in mirrored-channel mode). When mirroring, the effective memory that is available to the system is only half of what is installed.
One DIMM for each microprocessor is the minimum requirement. However, for optimal performance, install DIMMs in sets of three so that you distribute memory equally across all channels. If two microprocessors are installed, distribute memory across all channels and equally between the microprocessors. Install DIMMs in order as indicated in the following table for independent-channel mode and rank-sparing mode.
Table 2. DIMM population sequence for independent-channel mode and rank-sparing mode.

Two column table that contains DIMM population sequence information for independent-channel mode and rank-sparing mode
One installed microprocessor Two installed microprocessors
DIMM connectors 6, 4, 2, 5, 3, and 1 DIMM connectors 6, 12, 4, 8, 2, 10, 5, 11, 3, 7, 1, and 9

Install DIMM pairs in order as indicated in the following table for mirrored-channel mode.

Table 3. DIMM population sequence for mirrored-channel mode.

Four column table that contains DIMM population sequence information for mirror-channel mode
DIMM pair 1 microprocessor installed 2 microprocessors installed DIMMs per channel
1 DIMMs 4 and 21 DIMMs 4 and 21 1
2 DIMMs 3 and 11 DIMMs 8 and 101
3 none DIMMs 3 and 11
4 none DIMMs 7 and 91
  1. For mirrored-channel mode, the DIMM pair must be identical in size, type, and rank count. The two DIMMs in a channel do not need to be the same.

To install a DIMM, complete the following steps:

  1. Remove the upper compute node (see Removing the upper compute node).
  2. Read the documentation that comes with the DIMM.
  3. Locate the DIMM connectors (see lower DIMM connector locations and upper DIMM connector locations). Determine in which DIMM connector you want to install the DIMM.
  4. Remove the DIMM filler, if one is present.
  5. Touch the static-protective package that contains the DIMM to any unpainted metal surface on the Flex System chassis or any unpainted metal surface on any other grounded rack component in the rack in which you are installing the DIMM for at least 2 seconds; then, remove the DIMM from its package.
    Graphic illustrating the removal/install of DIMMs in the node
  6. Make sure that both retaining clips on the DIMM connector are in the open position.
  7. Turn the DIMM so that the DIMM keys align correctly with the DIMM connector on the system board.
    Attention: To avoid breaking the retaining clips or damaging the DIMM connector, handle the clips gently.
  8. Press the DIMM into the DIMM connector. The retaining clips lock the DIMM into the connector.
  9. Make sure that the small tabs on the retaining clips engage the notches on the DIMM. If there is a gap between the DIMM and the retaining clips, the DIMM has not been correctly installed. Press the DIMM firmly into the connector, and then press the retaining clips toward the DIMM until the tabs are fully seated. When the DIMM is correctly installed, the retaining clips are parallel to the sides of the DIMM.
    Attention: To maintain proper system cooling, do not operate the compute node without DIMMs or DIMM fillers installed in the DIMM connectors.
After you install the DIMM, complete the following steps:
  1. Install the upper compute node (see Installing the upper compute node for instructions).
  2. Install the Flex System x222 Compute Node into the chassis (see Installing a compute node in a chassis for instructions).
Parent topic: Removing and replacing Tier 1 customer replaceable units (CRUs)