IBM ZPRO memory mirroring

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UMMR

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May 21, 2014
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Hello,
I have a problem with a IBM ZPro 9228 (dual 3.0 GHz 5160 Xeon). I have upgraded the original RAM configuration (4x512MB DDR2 5300F, Hynix modules) to 16GB by installing 8x2GB Samsung modules. For the 1st time after the upgrade the machine recognized 16GB of RAM and correctly shows the BIOS message 164, RAM size changed. BUT, after the reboot, it shows only 8GB of RAM. Windows 7 Pro 64 bit says 16GB installed, 8GB usable (I know this it's based upon hardware info, so I presume the modules are working). I suspect this behaviour is caused by memory mirroring. In fact all the 8 RAM modules, tested in a different machine, worked OK. There is a way to disable the memory mirroring in IBM X series (9228 is in fact a X series system)? I can't see any option in BIOS. Can You help me?
Thank You all in advance.
Paolo
 
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bambiboom

bambiboom

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Apr 7, 2012
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UMMR,

I think plaintuts has a very good idea, but you also must be correct that the IBM must have settings to control the memory mirroring. The mirroring is similat to RAID 1 in the storage realm, it divides the RAM in half and uses the other half to duplicate the first half as a protection.

I had a look at the manual >

http://ps-2.kev009.com/pccbbs/pc_servers_pdf/31r2183.pdf

and pages 21-23 are the setup instructions, but I didn't see the mirroring mentioned.

The odd aspect is that the effect only occurred after adding RAM- which was detected at first but disappeared after rebooting. One thing to check is the pattern with which RAM is installed. Especially when there are two CPUs, the modules on a lot of systems are populated in a pattern. My Dell Precision T5400 has explicit instruction for it's eight slots ( and it also uses DDR2-5300) and the HP z420 includes a diagram on the back of the removable cover to get it right. As this pattern corresponds to memory channels, perhaps there is an effect when adding the 2GB modules in with the 512MB ones.

Let us know what you find out- intriguing problem.

Cheers,

BambiBoom

HP z420 (2014) > Xeon E5-1620 quad core @ 3.6 / 3.8GHz > 24GB ECC 1600 RAM > Quadro 4000 (2GB)> Samsung 840 SSD 250GB /Western Digital Black WD1003FZEX 1TB> M-Audio 192 sound card > AE3000 USB WiFi > HP 2711X, 27" 1920 X 1080 > Windows 7 Ultimate 64 >[Passmark system rating = 3923, 2D= 839 / 3D=2048]

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U

UMMR

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May 21, 2014
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Hello,
Thank You all for your help.
My machine came with the standard basic configuration, 4*512MB DIMMs (total 2GB). If I install 4x2GB modules (slots 1,3,5,7) plus 4x1GB modules (slots 2,4,6,8), the total amount of RAM is correctly recognized as 12 GB.
It looks like the machine automatically recognizes 8 identical modules as a memory mirroring configuration, no matter of the modules' size.
I tried 8x512MB: the workstation shows initially 4GB but only 2 GB after the first reboot.
I know, a viable solution wold be to install 4x4GB, but these modules are expensive...
Paolo


 
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bambiboom

bambiboom

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Apr 7, 2012
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Paolo,

I had another look at the user's manual for the IBM ZPRO 9228 and the section on memory mirroring begins near the bottom of page 48, See the section titled "Installing Memory Modules">

http://ps-2.kev009.com/pccbbs/pc_servers_pdf/31r2183.pdf

> and in particular near the bottom of Page 50 > "The following table shows the DIMM configuration upgrade sequence (non-mirroring mode)",

This mentions memory mirroring as being "enabled" and continues with a description of the population of the slots in a particular order. This is a bit confusing as it doesn't- or I'm not seeing- any specific instructions on enabling it, except the order of filling the slots. It may be as you say that filling all slots with identical size automatically enables mirroring. The configuration of the modules is in order of size. Have a look at these pages and perhaps you can see the key phrase. I had a look at the Precision T5400 as it too can use memory mirroring, but again everything involves the order of filling the slots. My T5400 is now using 8 X 2GB modules (also DDR2 5300), and shows in BIOS as 16GB. It originally had 4 X 2GB but I added the other 4 X2B when adding the second CPU (Xeon x5460).

It's still a mystery but feel the instructions must be somewhere between pages 48 and 50 of the manual. I'll have another look at both that and the T5400 manual as these systems seem to have a lot of commonality.

Cheers,

BambiBoom
 
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U

UMMR

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May 21, 2014
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Hello,
after many trials, I suspect a BIOS issue for this machine.
Or, a strange behaviour of this BIOS version (1.45, upgraded a week ago).
If I install modules of any manufacturer and size (in pair, I mean, obviously) the machine at 1st boot shows the total correct amount of RAM and the well known IBM error 164, memory size changed; the BIOS asks for the F1 or for the Enter key to continue.
By pressing F1 it looks like the machine automatically sets the RAM for the mirroring configuration, so at the reboot the RAM size is 1/2 of the actual RAM installed. BUT if I press Enter, bypassing the 164 error, Windows shows the correct amount of RAM installed and the workstation never complains again for the memory size changed.
Now I'm able to run without problems 14GB of RAM (4*2 + 2*1 DIMMs).
I think this size is enough for my needs, but I'll try the 16GB configuration with 8*2GB DIMMs.
Thank You again for Your help.
Paolo - Italy
 
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