HP ProLiant SE2170s Memory technology evolution: an overview of system memory
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- HP ProLiant SE2170s | Memory technology evolution: an overview of system memory - Page 1
DIMM configurations ...6 DIMM error detection/correction technologies 8 Memory protection technologies ...10 Advanced memory technologies ...12 Rambus DRAM...12 Double Data Rate SDRAM technologies 12 Fully-buffered DIMMs ...15 Importance of using HP-certified memory modules in ProLiant servers 18 - HP ProLiant SE2170s | Memory technology evolution: an overview of system memory - Page 2
overview of the memory technologies that we use in HP ProLiant servers, and describes how we evaluate these technologies. It also briefly summarizes the evolution of server memory and explores the different dynamic random access memory (DRAM) technologies. Processors use system memory to store the - HP ProLiant SE2170s | Memory technology evolution: an overview of system memory - Page 3
memory. The command portion of the address/command bus conveys instructions such as read, write, or refresh. When DRAM memory writes data to a cell, the memory controller selects the data's location. The memory driving CAS active before driving RAS active. CBR is used most often • Hidden refresh 3 - HP ProLiant SE2170s | Memory technology evolution: an overview of system memory - Page 4
memory access time by the number of memory bus clocks. System bus timing A system bus clock controls all computer components that execute instructions at various but related speeds control the components. These clocks use various clock multiplier and divider circuits to generate multiple signals. - HP ProLiant SE2170s | Memory technology evolution: an overview of system memory - Page 5
Operation Instruction SDRAM technology DRAMs are asynchronous, that is, without a memory bus clock. The memory number of system clock cycles required to read or write data. SDRAM uses a memory bus clock to synchronize the input and output signals on the memory chip. This simplifies the memory - HP ProLiant SE2170s | Memory technology evolution: an overview of system memory - Page 6
. This lets you add more memory modules to the memory bus, increasing capacity. DIMM configurations DIMMs are available in several configurations, depending on the number and type of DRAMs used as well as the number of memory blocks, called ranks, the DIMM supports. Single-sided and double-sided - HP ProLiant SE2170s | Memory technology evolution: an overview of system memory - Page 7
slots, chipsets now use multiple memory buses. If the total number of ranks in the populated DIMM slots exceeds the maximum number of loads, the chipset can support, the server may not boot properly or it may not operate reliably. Some systems check the memory configuration while booting to detect - HP ProLiant SE2170s | Memory technology evolution: an overview of system memory - Page 8
memory-related problems, we advise our customers to use only HP-certified DIMMs, which are available in the memory option kits for each ProLiant server (see the "Importance of using HP-certified memory modules in ProLiant servers data loss. Memory errors are classified by the number of bits that - HP ProLiant SE2170s | Memory technology evolution: an overview of system memory - Page 9
of low-cost, high-capacity memory modules • Server virtualization Advanced ECC memory To improve memory protection beyond standard ECC, HP introduced Advanced ECC technology in 1996. HP and most other server manufacturers use this solution in industry-standard products. Advanced ECC can correct - HP ProLiant SE2170s | Memory technology evolution: an overview of system memory - Page 10
ECC does not provide failover capability. If there is a memory failure, you must shut down the system before replacing the memory. The latest generation of HP ProLiant servers offers several forms of Advanced Memory Protection that provide increased fault tolerance for applications requiring higher - HP ProLiant SE2170s | Memory technology evolution: an overview of system memory - Page 11
-channel memory configuration requires dual-rank DIMMs. For more information, refer to the server's user guide. In a system with three channels per memory controller, two channels operate normally and the third channel is the spare. Online Spare Memory mode does not require operating system support - HP ProLiant SE2170s | Memory technology evolution: an overview of system memory - Page 12
a multi-drop serial bus to communicate with each RDRAM chip rather than using an advanced memory buffer (AMB). RDRAM delivered better memory bandwidth than SDRAM, but it required a different memory bus design and significantly more expensive RDRAM chips. Double Data Rate (DDR) SDRAM, with a design - HP ProLiant SE2170s | Memory technology evolution: an overview of system memory - Page 13
and DDR1. Instead of using a 3.3-V operating voltage of SDRAM, DDR1 uses the 2.5-V signaling specification SSTL_2. This low-voltage used by standard SDRAM DIMMs. DDR1 is versatile enough for both desktop PCs and servers. To vary the cost of DDR1 DIMMs for these different markets, memory - HP ProLiant SE2170s | Memory technology evolution: an overview of system memory - Page 14
and power consumption. DDR3 manufacturers began fabrication using with 90 nm technologies. With increasing production volumes, they are moving toward 70 signal integrity by reducing the number of stubs and their length. This feature requires the controller to support "write leveling" on DDR3 DIMMs - HP ProLiant SE2170s | Memory technology evolution: an overview of system memory - Page 15
a stub-bus topology with parallel branches (stubs) that connect to a shared memory bus (Figure 11). Each DIMM connects to the data bus using a set of pin connectors. For the electrical signals from the memory controller to reach the DIMM bus-pin connections at the same time, all the traces must be - HP ProLiant SE2170s | Memory technology evolution: an overview of system memory - Page 16
DIMM) specification, a serial interface that eliminates the parallel stub-bus topology and allows higher memory bandwidth while maintaining or increasing memory capacity. The FB-DIMM architecture has serial links between the memory controller and the FB-DIMMs connected in a daisy chain configuration - HP ProLiant SE2170s | Memory technology evolution: an overview of system memory - Page 17
costs more, uses more power, and has increased latency. As a result, the industry has not implemented FB-DIMMs for DDR3. Instead, engineers have increased server memory capacities by designing systems with Non-Uniform Memory Access (NUMA) architectures, which feature up to four memory channels for - HP ProLiant SE2170s | Memory technology evolution: an overview of system memory - Page 18
-Online Spare Memory, Mirrored Memory, and Lockstep Memory-are optimized for each server series. For ProLiant servers with AMP, the AMP mode you select determines the DIMM configuration. HP memory option kits ensure correct configuration for each AMP mode. Third, using HP memory option kits - HP ProLiant SE2170s | Memory technology evolution: an overview of system memory - Page 19
Resource description JEDEC Web site HP ProLiant Server Memory web page DDR3 memory technology, technology brief Web address http://www.jedec.org http://h18004.www1.hp.com/products/servers/options/memorydescription.html http://h20000.www2.hp.com/bc/docs/support/SupportManual /c02126499/c02126499.pdf
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Memory technology evolution: an overview
of system memory technologies
Technology brief, 9
th
edition
Introduction
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2
Basic DRAM operation
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2
DRAM storage density and power consumption
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4
Memory access time
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4
System bus timing
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4
Memory bus speed
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5
Burst mode access
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5
SDRAM technology
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5
Bank interleaving
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6
Increased bandwidth
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6
Registered SDRAM modules
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6
DIMM configurations
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6
DIMM error detection/correction technologies
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8
Memory protection technologies
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10
Advanced memory technologies
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12
Rambus DRAM
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12
Double Data Rate SDRAM technologies
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12
Fully-buffered DIMMs
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15
Importance of using HP-certified memory modules in ProLiant servers
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18
Conclusion
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18
For more information
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19
Call to action
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19