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Help understanding Dell's memory descriptions

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April 1, 2009 6:01:21 PM

I was looking at Dell's new Nehalem-based PowerEdge R710 server, and saw this listed under the memory options:

Quote:
4GB Memory (4x1GB), 1066MHz Single Ranked UDIMMs for 2 Processors, Adv ECC [subtract $430]
6GB Memory (6x1GB), 1333MHz Single Ranked UDIMMs for 2 Processors,Optimized [subtract $340]
8GB Memory (4x2GB), 1066MHz Dual Ranked UDIMMs for 2 Processors, Adv ECC [subtract $300]
12GB Memory (6x2GB), 1066MHz Dual Ranked UDIMMs for 2 Processors, Optimized [subtract $100]
12GB Memory (6x2GB), 1333MHz Dual Ranked UDIMMs for 2 Processors, Optimized [subtract $40]
16GB Memory (8x2GB), 1066MHz Dual Ranked UDIMMs for 2 Processors, Adv ECC [Included in Price]
24GB Memory (12x2GB),1066MHz Dual Ranked UDIMMs for 2 Processors, Optimized [add $400]
24GB Memory (12x2GB), 800MHz Dual Ranked RDIMMs for 2 Processors, Adv ECC [add $1,000]
24GB Memory (6x4GB), 1333MHz Dual Ranked RDIMMs for 2 Processors, Optimized [add $1,200]
32GB Memory (8x4GB), 1066MHz Dual Ranked RDIMMs for 2 Processors, Adv ECC [add $1,400]
..........


Ok, so I get the difference between UDIMMs and RDIMMs (unregistered vs registered). But what does Dell mean by Advanced ECC and Optimized!?!

Any info would be greatly appreciated. Thanks!
April 1, 2009 6:18:15 PM

Looking over it again my guess would be that "optimized" means that it's using all 3 memory channels? But then why are the first two different? So does "optimized" mean using all 3 memory channels and 1066+ speed? But then on their listing it also shows:
Quote:
..........
72GB Memory (18x4GB), 800MHz Dual Ranked RDIMMs for 2 Processors, Optimized [add $3,400]
96GB Memory (12x8GB), 1066MHz Dual Ranked RDIMMs for 2 Processors,Optimized [add $15,400]
144GB Memory (18x8GB), 800MHz Dual Ranked RDIMMs for 2 Processors,Optimized [add $22,900]
How are the 72GB and 144GB "optimized" then?
a b } Memory
April 2, 2009 7:41:16 AM

Three channels per CPU, with 3 sticks of memory per channel (9 DIMMs, triple channel mode)? IIRC, that's the most that i7 supports.
Related resources
April 2, 2009 2:31:42 PM

cjl said:
Three channels per CPU, with 3 sticks of memory per channel (9 DIMMs, triple channel mode)? IIRC, that's the most that i7 supports.

Yeah, I just couldn't figure out what Dell was trying to mean by 'optimized" and "Adv ECC".
a b } Memory
April 2, 2009 3:30:56 PM

But they could be optimized because it is still triple channel...

It looks like every "Optimized" is triple channel.
April 2, 2009 5:34:00 PM

cjl said:
But they could be optimized because it is still triple channel...

It looks like every "Optimized" is triple channel.

Thanks for the confirmation. Maybe they just put "Adv ECC" there for fun.
a b } Memory
April 2, 2009 6:08:39 PM

Well, ECC memory is definitely different from non-ECC (most desktop memory is non-ECC). I'm not sure what the "advanced" part means though.
April 24, 2009 1:20:49 PM

From a Dell white paper on the subject:

DDR3 Memory
There are two types of DDR3 memory supported by these systems: UDIMM and RDIMM. UDIMMs are unbuffered DIMMs, while RDIMMs are registered DIMMs. The registry allows RDIMMs to potentially run at higher frequencies and support more DIMMs within a memory channel.

NOTE: Dell systems only support UDIMMs with ECC capabilities; UDIMMs purchased for consumer systems will typically not work in the servers. Generally, RDIMMs should be purchased by customers who need large amounts of memory (up to 8 GB DIMMs), a broader future memory expansion roadmap (due to the ability to achieve three DIMMs per channel), and the latest RAS features (address parity). UDIMMs should be purchased by customers who need a limited amount of memory and are looking for power and cost savings. RDIMMs use about 1 W of power more per DIMM than the comparable UDIMMs due to the register feature. However, the register feature will allow for performance improvements when the memory is being highly utilized.

Memory Population
Each CPU has three integrated MCHs that have their own memory channel. Memory can be accessed across the CPUs, or the system can be configured in non-uniform memory architecture (NUMA). This can be configured via a BIOS configuration setting. Figure 1 shows the CPU and memory layout on the R710 model that supports up to 3 DIMMs per channel

Memory Optimized Mode
In this mode, the MCHs run independently of each other; for example, one can be idle, one can be performing a write operation, and the other can be preparing for a read operation. Memory may be installed in one, two, or three channels. To fully realize the performance benefit of the memory optimized mode, all three channels per CPU should be populated. This implies that some ‘atypical’ memory configurations, such as 3GB, 6GB, or 12GB, will yield the best performance. This is the recommended mode unless specific RAS features are needed.

Advanced ECC Mode
This mode uses two MCHs and “ties” them together to emulate a 128-bit data bus DIMM. This is primarily used to achieve a Single Device Data Correction (SDDC) for DIMMs based on x8 DRAM technology. SDDC is supported with x4 based DIMMs in every memory mode. One MCH is completely un-utilized, and any memory installed in this channel will generate a warning message during POST.



So there is your difference.....Optimized takes full advantage of the three memory channels while "Advanced ECC" ties two together and leaves on not used, doing so for better checking.
Anonymous
a b } Memory
August 13, 2010 5:31:03 PM

Quick questions: So if I'm buying a new server with 12 GB of memory the Rdimms would be better? Also they would use less power, correct?
I will be running a large SQL data base made for SQL 2005.






vseven said:
From a Dell white paper on the subject:

DDR3 Memory
There are two types of DDR3 memory supported by these systems: UDIMM and RDIMM. UDIMMs are unbuffered DIMMs, while RDIMMs are registered DIMMs. The registry allows RDIMMs to potentially run at higher frequencies and support more DIMMs within a memory channel.

NOTE: Dell systems only support UDIMMs with ECC capabilities; UDIMMs purchased for consumer systems will typically not work in the servers. Generally, RDIMMs should be purchased by customers who need large amounts of memory (up to 8 GB DIMMs), a broader future memory expansion roadmap (due to the ability to achieve three DIMMs per channel), and the latest RAS features (address parity). UDIMMs should be purchased by customers who need a limited amount of memory and are looking for power and cost savings. RDIMMs use about 1 W of power more per DIMM than the comparable UDIMMs due to the register feature. However, the register feature will allow for performance improvements when the memory is being highly utilized.

Memory Population
Each CPU has three integrated MCHs that have their own memory channel. Memory can be accessed across the CPUs, or the system can be configured in non-uniform memory architecture (NUMA). This can be configured via a BIOS configuration setting. Figure 1 shows the CPU and memory layout on the R710 model that supports up to 3 DIMMs per channel

Memory Optimized Mode
In this mode, the MCHs run independently of each other; for example, one can be idle, one can be performing a write operation, and the other can be preparing for a read operation. Memory may be installed in one, two, or three channels. To fully realize the performance benefit of the memory optimized mode, all three channels per CPU should be populated. This implies that some ‘atypical’ memory configurations, such as 3GB, 6GB, or 12GB, will yield the best performance. This is the recommended mode unless specific RAS features are needed.

Advanced ECC Mode
This mode uses two MCHs and “ties” them together to emulate a 128-bit data bus DIMM. This is primarily used to achieve a Single Device Data Correction (SDDC) for DIMMs based on x8 DRAM technology. SDDC is supported with x4 based DIMMs in every memory mode. One MCH is completely un-utilized, and any memory installed in this channel will generate a warning message during POST.



So there is your difference.....Optimized takes full advantage of the three memory channels while "Advanced ECC" ties two together and leaves on not used, doing so for better checking.

October 25, 2010 6:58:26 AM

The RDIMM memory will "POTENTIALY" be faster, but will consume 1W / RDIMM more because of the registry feature.
October 26, 2010 3:25:29 AM

vseven said:
From a Dell white paper on the subject:

DDR3 Memory
There are two types of DDR3 memory supported by these systems: UDIMM and RDIMM. UDIMMs are unbuffered DIMMs, while RDIMMs are registered DIMMs. The registry allows RDIMMs to potentially run at higher frequencies and support more DIMMs within a memory channel.

NOTE: Dell systems only support UDIMMs with ECC capabilities; UDIMMs purchased for consumer systems will typically not work in the servers. Generally, RDIMMs should be purchased by customers who need large amounts of memory (up to 8 GB DIMMs), a broader future memory expansion roadmap (due to the ability to achieve three DIMMs per channel), and the latest RAS features (address parity). UDIMMs should be purchased by customers who need a limited amount of memory and are looking for power and cost savings. RDIMMs use about 1 W of power more per DIMM than the comparable UDIMMs due to the register feature. However, the register feature will allow for performance improvements when the memory is being highly utilized.

Memory Population
Each CPU has three integrated MCHs that have their own memory channel. Memory can be accessed across the CPUs, or the system can be configured in non-uniform memory architecture (NUMA). This can be configured via a BIOS configuration setting. Figure 1 shows the CPU and memory layout on the R710 model that supports up to 3 DIMMs per channel

Memory Optimized Mode
In this mode, the MCHs run independently of each other; for example, one can be idle, one can be performing a write operation, and the other can be preparing for a read operation. Memory may be installed in one, two, or three channels. To fully realize the performance benefit of the memory optimized mode, all three channels per CPU should be populated. This implies that some ‘atypical’ memory configurations, such as 3GB, 6GB, or 12GB, will yield the best performance. This is the recommended mode unless specific RAS features are needed.

Advanced ECC Mode
This mode uses two MCHs and “ties” them together to emulate a 128-bit data bus DIMM. This is primarily used to achieve a Single Device Data Correction (SDDC) for DIMMs based on x8 DRAM technology. SDDC is supported with x4 based DIMMs in every memory mode. One MCH is completely un-utilized, and any memory installed in this channel will generate a warning message during POST.



So there is your difference.....Optimized takes full advantage of the three memory channels while "Advanced ECC" ties two together and leaves on not used, doing so for better checking.



Thanks you for the post.



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October 31, 2011 12:06:58 PM

I have a follow up question. I have a R710 that I am going from 128 gig using 8 gig dimms to 192 gig using 16 gig dimms.
Do I need to set memory optimized mode in the bios , 6.0.7, or am I good ?
I am glad I found this post.

Thanks,Rob
January 9, 2012 10:57:55 AM

rscarb99 said:
I have a follow up question. I have a R710 that I am going from 128 gig using 8 gig dimms to 192 gig using 16 gig dimms.
Do I need to set memory optimized mode in the bios , 6.0.7, or am I good ?
I am glad I found this post.

Thanks,Rob


Hi Rob.

Can you please advise how you had the 128Gb configured in your R710?

Balan
May 11, 2012 8:48:06 PM

An important note on this same subject: I just noticed that several Dell R510 servers that I recently bought with 12GB Optimized RAM (3x4GB) were only showing 8GB RAM. I verified they had 3x4GB sticks. I then noticed when the servers first boot they say, "Configuring memory. Please wait...". After displaying that message for a couple of seconds it then shows the blue Dell logo and all the other system booting information.

I went into the BIOS and selected "memory settings" then arrowed down to "memory operating mode". It was set by default to "Spare Mode". The available options are Optimizer, Spare, Mirror, and Advanced ECC. I changed it to "Optimizer Mode" and rebooted. My servers now use all three sticks and show 12GB RAM instead of 8GB. I don't know why they were set to "Spare Mode", but the configuration I chose when buying them was "12GB Memory (3x4GB), 1333 MHz Dual Rank LVRDIMMs for 1 Processor, Optimized". Something to watch out for.
!