IBM 7945D2U User Manual - Page 7

Leadership enterprise server with significantly lower cost of ownership in a highly available and expandable, rack-dense, 2U dual-socket server six 2GB single-rank DIMMs by 7% for SPECjbb2005. Dual-rank DIMMs are also better than quadrank DIMMs because quad-rank DIMMs will cause the memory speed to be down-clocked. Another important guideline is to populate equivalent ranks per channel. For instance, mixing one single-rank DIMM and one dual-rank DIMM in a channel should be avoided. Notes: It is important to populate all three memory channels in each processor. The relative memory bandwidth decreases as the number of channels populated decreases. This is because the bandwidth of all the memory channels is utilized to support the capability of the processor. So, as the channels are decreased, the burden to support the requisite bandwidth is increased on the remaining channels, causing them to become a bottleneck. RDIMMs and UDIMMs cannot be used in the same server. If 1.5V and 1.35V DIMMs are mixed, all DIMMs will run at 1.5V. In addition to Chipkill error correction, the x3650 M3 offers an additional level of IBM Active Memory protection: memory mirroring. Memory mirroring works much like disk mirroring. The total memory is divided into three channels: a primary channel, a backup channel, and an unused channel. Data is written concurrently to both the primary and backup channels. If a DIMM fails in one of the DIMMs in the primary channel, it is instantly disabled and the mirrored memory in the backup channel becomes active (primary) until the failing DIMM is replaced. One-third of total memory is available for use at any one time with mirroring enabled. (Note: Due to the double writes to memory, performance is affected.) Because the third channel is disabled with mirroring active, there is no point in populating it with memory. Mirroring is handled at the hardware level; no operating system support is required. DDR3 memory is currently available in 2GB, 4GB, 8GB and 16GB RDIMMs, or 2GB and 4GB UDIMMs. DIMMs are installed individually (not in pairs). However, for performance reasons, in a 2-processor system, it's best to install a DIMM per processor. Maximum memory capacity and speed in 2-processor configurations include: Memory Frequency 1333MHz 1333MHz 1066MHz 800MHz 800MHz 800MHz1333MHz (Mirroring) DIMMs per Channel 1 (6 DIMMs) 2 (12 DIMMs) 2 (12 DIMMs) 3 (18 DIMMs) 2 (12 DIMMs) 2 (12 DIMMs) Max. Memory Capacity 48GB RDIMM 24GB UDIMM 96GB RDIMM 48GB UDIMM 96GB RDIMM 48GB UDIMM 5600 Series E5645, E5649, L5640 and X56xx 1333MHz processors E5645, E5649, L5640 and X56xx 1333MHz processors E560x, E5620, X5647, L5609 and L5630 144GB RDIMM All of processors 192GB RDIMM All of processors 64GB RDIMM 16GB UDIMM All of processors Integrated Virtualization All models of the x3550 M3 support a USB 2.0 Flash Key installed preloaded with VMware vSphere Hypervisor (formerly ESXi). Rather than management through a Service Console based on a Linux operating system, vSphere Hypervisor relies on aggregate management tools, including VirtualCenter, the Remote Command Line interface and the introduction of CIM for standards-based and agentless hardware monitoring. vSphere Hypervisor includes all the performance, scalability and compatibility features of a hypervisor installed on disk, including full VMFS support across FC SAN, iSCSI SAN, and NAS, and 4-way VSMP. Because it runs from flash memory, it's extremely fast and ideal for diskless configurations. It also offers enhanced security, because it runs without an operating systembased console and is updated/patched much like firmware. 7 Please see the Legal Information section for important notices and information.