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R715 Memory Configuration Not Optimal - After Upgrade
Hello everyone,
I have been attempting to find a solution to a memory configuration issue by reading the Hardware Owners Manual, and Technical Guide but am unable to determine what I am doing incorrectly.
I currently have a Dell PowerEdge R715 with 64GB of memory in the following configuration:
Qty 8 HMT31GR7BFR4A-H9 8GB 2Rx4 PC3L 10600R
A1 Memory module slot A1 (white release lever) 8GB 2Rx4 PC3L 10600R
A5 Memory module slot A5
A2 Memory module slot A2 (white release lever) 8GB 2Rx4 PC3L 10600R
A6 Memory module slot A6
A3 Memory module slot A3 (white release lever) 8GB 2Rx4 PC3L 10600R
A7 Memory module slot A7
A4 Memory module slot A4 (white release lever) 8GB 2Rx4 PC3L 10600R
A8 Memory module slot A8
B1 Memory module slot B1 (white release lever) 8GB 2Rx4 PC3L 10600R
B5 Memory module slot B5
B2 Memory module slot B2 (white release lever) 8GB 2Rx4 PC3L 10600R
B6 Memory module slot B6
B3 Memory module slot B3 (white release lever) 8GB 2Rx4 PC3L 10600R
B7 Memory module slot B7
B4 Memory module slot B4 (white release lever) 8GB 2Rx4 PC3L 10600R
B8 Memory module slot B8
When I attempted to add an additional 64 GB of memory (by adding Qty. 4 SNP20D6FC/16G
16GB 2Rx4 PC3L 12800R) in the BELOW configuration I received the “Memory not optimal” error at bootup. I was still able to boot the server, but had to acknowledge the error to proceed.
A1 Memory module slot A1 (white release lever) 8GB 2Rx4 PC3L 10600R
A5 Memory module slot A5 16GB 2Rx4 PC3L 12800R
A2 Memory module slot A2 (white release lever) 8GB 2Rx4 PC3L 10600R
A6 Memory module slot A6 16GB 2Rx4 PC3L 12800R
A3 Memory module slot A3 (white release lever) 8GB 2Rx4 PC3L 10600R
A7 Memory module slot A7
A4 Memory module slot A4 (white release lever) 8GB 2Rx4 PC3L 10600R
A8 Memory module slot A8
B1 Memory module slot B1 (white release lever) 8GB 2Rx4 PC3L 10600R
B5 Memory module slot B5 16GB 2Rx4 PC3L 12800R
B2 Memory module slot B2 (white release lever) 8GB 2Rx4 PC3L 10600R
B6 Memory module slot B6 16GB 2Rx4 PC3L 12800R
B3 Memory module slot B3 (white release lever) 8GB 2Rx4 PC3L 10600R
B7 Memory module slot B7
B4 Memory module slot B4 (white release lever) 8GB 2Rx4 PC3L 10600R
B8 Memory module slot B8
I read in the Owners Manual that the highest ranked DIMMS should be installed first. Although the memory is all quad ranked, I decided to place the 16GB DIMMS “First” as follows:
A1 Memory module slot A1 (white release lever) 16GB 2Rx4 PC3L 12800R
A5 Memory module slot A5 8GB 2Rx4 PC3L 10600R
A2 Memory module slot A2 (white release lever) 16GB 2Rx4 PC3L 12800R
A6 Memory module slot A6 8GB 2Rx4 PC3L 10600R
A3 Memory module slot A3 (white release lever)
A7 Memory module slot A7 8GB 2Rx4 PC3L 10600R
A4 Memory module slot A4 (white release lever)
A8 Memory module slot A8 8GB 2Rx4 PC3L 10600R
B1 Memory module slot B1 (white release lever) 16GB 2Rx4 PC3L 12800R
B5 Memory module slot B5 8GB 2Rx4 PC3L 10600R
B2 Memory module slot B2 (white release lever) 16GB 2Rx4 PC3L 12800R
B6 Memory module slot B6 8GB 2Rx4 PC3L 10600R
B3 Memory module slot B3 (white release lever)
B7 Memory module slot B7 8GB 2Rx4 PC3L 10600R
B4 Memory module slot B4 (white release lever)
B8 Memory module slot B8 8GB 2Rx4 PC3L 10600R
I had no success with this method. My thoughts are that the server may want all 8 slots filled.
Any ideas? My VAR is not giving me any assistance.
Anonymous
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February 23rd, 2016 11:00
Hello.
Your memory configuration is not optimal because the memory channels are not balanced thus; slots on each channel must have identical memory modules for both processors. For optimal memory, you will have:
A1, A2, B1 &B2 =16 GB
A5, A6, B5, &B6 = 8 GB
The rest of the slots ought to remain empty.This will give you total memory capacity of 96 GB. However, if want more than 96 GB of memory and are looking to use 16 GB DIMMs, consider purchasing 4 additional modules(16 GB) to be populated on the remaining slots in the similar manner.
craziefro
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February 23rd, 2016 13:00
I tried the memory in the listed solution of :
A1, A2, B1 &B2 =16 GB
A5, A6, B5, &B6 = 8 GB
and still received the "Memory not optimal" error. Thinking that it could be an issue with 2 different speeds of memory, I tried only installing the 16GB modules as:
A1, A2, B1, B2 and still received the "Memory not optimal" error.
Thanks again. I greatly appreciate the assistance!
craziefro
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February 23rd, 2016 13:00
Thanks for the info Robert! I will try to see if that configuration works.
Where can I find more information about the "Channels" of memory as they relate to my Dell server. I have more experience with HP (boooo) and find it more difficult to understand the Dell layout.
Anonymous
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February 24th, 2016 07:00
Mixing memory with different speed means the channels will operate at the fast frequency. Ensure that you set the memory mode to Memory Optimized. Again, for optimal memory configuration, the memory channels must have identical DIMMs hence balanced. You will therefore need additional 4 8GB DIMMs (total of 8 8GB modules) to populate on the rest of the slots i.e A5, A6, A7 &A8 and B5, B6,B7 &B8. Populating only slots A5 &A6 on CPU 1 and B5 &B6 on CPU 2 creates memory imbalance with channels C&D on CPU 1 and CPU 2. Memory in the channels have to match. See diagrammatic illustration below:
craziefro
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February 24th, 2016 08:00
Thanks for the info Robert,
I'm a little confused, you stated that A1, A2, B1 &B2 =16 GB & A5, A6, B5, &B6 = 8 GB would provide optimal memory configuration, but when I installed it in this configuration it was not optimal.
Also, it was my understanding that the mixed memory speeds would operate at the slowest common frequency, not the fastest frequency.
With the configuration of A1, A2, B1 &B2 =16 GB & A5, A6, B5, &B6 = 8 GB the DIMMS would create an imbalance across channels C&D correct?
In your latest post, you stated that memory channels must have identical DIMMS in each channel, does that mean that Channel A,B,C,D must be populated or can channel A,B be populated only?
craziefro
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February 24th, 2016 09:00
Robert,
Thanks for the update.
I am currently on BIOS 1.5.2
I did attempt to only populate A1, A2, B1 &B2 with 16GB DIMM, I still received the "Memory not optimal error"
Anonymous
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February 24th, 2016 09:00
Pardon me, the channels will operate at slower speed when memory with different speeds are mixed. With the configuration of A1, A2, B1 &B2 =16 GB & A5, A6, B5, &B6 = 8 GB, there won't an imbalance across channels C&D because they are empty. Imbalance occurs when memory on channels C&D does not match memory on A&B. Yes, can populate only A&B channels. Some BIOS versions do not support 16 GB memory modules. What is your current BIOS?
Anonymous
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February 24th, 2016 10:00
The BIOS is way out of date. Apply the following BIOS updates first then followed by respective iDRAC updates.
BIOS iDRAC
BIOS iDRAC
BIOS iDRAC
BIOS
craziefro
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February 24th, 2016 11:00
Thanks for the info Robert. Do you know if I can accomplish the same updates by using the Dell Deployment Toolkit CD?
Anonymous
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February 24th, 2016 12:00
Sure: <ADMIN NOTE: Broken link has been removed from this post by Dell>. See instructions at the bottom of the page. Mean while, you may also perform updates via the LifeCycle Controller (LCC) using F10 during POST. Got to Platform Updates and point to ftp.dell.com site.
craziefro
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February 25th, 2016 06:00
Thanks Robert, I will check that out.
I was looking at downloads.dell.com/.../poweredge-r715_reference%20guide3_zh-cn.pdf
And the common theme that I see is that in almost all configurations, A1,A2,A3,A4 B1,B2,B3,B4 are always fully populated. I do not see the configuration that you suggested of A1, A2, B1 &B2 =16 GB & A5, A6, B5, &B6 = 8 GB listed
Anonymous
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February 26th, 2016 07:00
You are perfectly right. However, there can be different configurations depending on the number of available memory modules and whether they are of the same capacity or mixed capacity. Now if we are looking to populate all channels as per the guide, try adding 4 more 16 GB modules as previously suggested. Have you already updated the BIOS?
craziefro
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February 29th, 2016 14:00
Robert,
I upgraded the BIOS, Lifecycle Controller, iDRAC and tried the following configuration of memory:
A1,A2, B1,B2 X 16GB
and still received the not optimal error. To ensure that the issue was not related to the 16GB DIMMS, I installed the 8GB DIMMS in the following :
A1,A2, B1,B2 X 8GB
I still received the not optimal error.
I noticed the first time that I booted into the (non updated version) Lifecycle controller, Error messages (these before I had made any changes to the memory configuration) *Please see attached Photo*
After the updates were performed, I did not notice this error when I entered the Life cycle Controller.
craziefro
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March 1st, 2016 10:00
I installed the following configuration:
A1,A2,A3,A4 B1,B2,B3,B4 - 8GB
added
A5,A6,A7,A8 B5,B6,B7,B8 - 4GB DIMMs
System was satisfied with the memory. Is it possible that the documentation is incorrect and all channels must be populated?
Anonymous
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March 1st, 2016 14:00
Hello.
I have looked at a couple of documentations including the R715 source book. However, I haven't found this requirement. Allow me to consult then I will post my findings.