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CarWolff
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ESXi v5.1 Ram/Memory Help

Hey Guys,

I just built a machine to run ESXi v5.1 on. Built the machine and did a fresh install of ESXi v5.1.

Anyway, I am having a problem with ESXi not recognizing the maximum ram I have on my system.

I have 16 (2x8gb) Gigs of Physical Ram/Memory, and even the bios sees it as 16 Gigs, but when ESXi loads up it only sees 7.5GB and now I am at loss as to what is happening. I know that even the free version supports up to 32gigs physical so that shouldn't be the problem. And i doubt the mobo/bios would be the problem since they also recognize the max ram I have currently installed.

Any help would be much appreciated.

PC Specs:

MOBO: MSI A55M-P33 FM1 AMD A55 (Hudson D2) Micro ATX AMD Motherboard with UEFI BIOS

CPU: AMD A6-3650 Llano 2.6GHz Socket FM1 100W Quad-Core Desktop APU (CPU + GPU) with DirectX 11 Graphic AMD Radeon HD

RAM: G.SKILL Ares Series 16GB (2 x 8GB) 240-Pin DDR3 SDRAM DDR3 1333 (PC3 10666) Desktop Memory Model F3-1333C9D-16GAO

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spravtek
Expert
Expert

Well .. I don't need to tell you this system is probably not supported by VMware Smiley Wink

But besides that, are there any "advanced" memory settings available in the BIOS?

Your story kinda sounds like this: http://www.vdsyn.com/esxi-5-0-hosts-not-showing-up-all-the-memory-installed/

Though it's of course an entirely different system.

I had an issue with memory once, kinda similar, and it was only solved when I manually lowered the speed of the memory in the BIOS.

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JarryG
Expert
Expert

I have similar problem (even with vmware-supported hardware), but fortunatelly I'm not loosing so much (only ~0.3 GB):

http://communities.vmware.com/message/2128900

BTW, are you aware that MSI does not list the memory you use as supported for your mobo?

http://www.msi.com/file/test_report/TR10_2526.pdf

I *think* in your case it might have something to do either with module-geometry (i.e. single-sided versus double-sided ram modules) or chip size used. Try to plug-in only one ram-module and see how much ram you see then. And try to flash the latest bios, if you did not do it already...

_____________________________________________ If you found my answer useful please do *not* mark it as "correct" or "helpful". It is hard to pretend being noob with all those points! 😉
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CarWolff
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Thanks for the reply. I think you might be on to something. I will try to mess around with the ram options in the bios when I get out from work.

Yes, I knew my mobo isnt supported. Even though, I was under the impression that as long as you dont go over the ram limitation of ESXi then your good, since ram is ram.

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CarWolff
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Hey thanks for the reply. Yeah at least yours isn't that bad but still, you want to get what you paid for right? Having 16GB installed and only detecting 7.5 is so bad.

I wasn't aware that my memory is not on the MSI supported list. Although, when I enter the bios, my mobo lists my system having 16GB. I also have flashed the bios to the latest version with no difference when running esxi.

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CarWolff
Contributor
Contributor

Update:

So I have tinkered with the bios settings some more but no luck. So I tried switching the dimms around, still got the same thing, i left 1 dimm on DIMM slot1 and removed the one on DIMM slot2, bios reported back 8GB which is correct. I pulled out dimm on slot 1 and left DIMM on slot2 and it would not go to bios.

Seems like its a problem with dual channel configuration? Maybe ESXi is still not recognizing that it is dual channel slots?

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LaurenHorn
Contributor
Contributor

Speaking in ignorance of the specifics of your hardware, I might suggest you try lowering the memory clock (if that's supported by your BIOS), or otherwise backing off from highest-performance settings, if you have not already done so.

My apologies, I reread the thread and see that this option has already been covered.  I'll adjust my advice.

-> Once more about speed: if you haven't already, back off all the way in the BIOS, setting your machine to run as slowly as it can (though you likely would not prefer to use it that way, long-term) even if the result isn't acceptable, any information you glean might be useful.

-> Remove every piece of extraneous hardware from the MoBo, including disabling every built-in peripheral that you can through BIOS if it is not absolutely required to boot ESXi.  (I think you can even remove or disable the NIC.)

-> If you can, borrow RAM sticks from a workstation; a couple of 2 or 4GB modules would help you test your dual-channel theory.

If you (alas) determine that you'll have to replace the RAM, you might run into the trouble I did with my last ESXi build: none of the configurations explicitly supported by the manufacturer totalled 16GB.  I went to the web sites of a few prominent brands and searched for my mobo in their support lists.  (On the way, I turned up many tales of woe from people who could make 8GB work but not 16GB.)  I  found a brand (Corsair, in my case) that sold a 16GB kit that they would guarantee would work on my specific mobo.  I paid a few extra dollars buy that particular kit, rather than two 8GB kits of apparently identical parts, because for all I know the 16GB kit had been tested together and had been selected with tighter timing tolerances to work with "problem" mobos such as mine.

Good luck!

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Linjo
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My homelab-server would not accept 8Gb DIMM if they where not ECC, so that could be something to check also.

(It did support up to 4Gb non-ecc)

// Linjo

Best regards, Linjo Please follow me on twitter: @viewgeek If you find this information useful, please award points for "correct" or "helpful".
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JarryG
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> I pulled out dimm on slot 1 and left DIMM on slot2 and it would not go to bios.

> Seems like its a problem with dual channel configuration?

IIRC, your motherboard does not support "single dimm in slot2" configuration. If you use only one dimm, it must be always in slot1. Try to test both dimms in slot1 to see if they are correctly recognised...

_____________________________________________ If you found my answer useful please do *not* mark it as "correct" or "helpful". It is hard to pretend being noob with all those points! 😉
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CarWolff
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>Once more about speed: if you haven't already, back off all the way in the BIOS, setting   your machine to run as slowly as it can (though you likely would not   prefer to use it that way, long-term) even if the result isn't   acceptable, any information you glean might be useful.

Thank you for your input. I understand that we are just in the diagnosis stage and we're trying to find the cause/solution for whats happening and try to get it working right Smiley Happy

I had it set at auto at first but now its manually set at 1333 to see if it was gonna fix it but it did not. I will try to set the ram speed at its lowest and check again.

>If you can, borrow RAM sticks from a workstation; a couple of 2  or 4GB  modules would help you test your dual-channel theory.

I'll could probably check the dual channel theory. I could swap them out and use my desktop pc's ram, altho they would be smaller size 8gig (2x4GB).

>Remove every piece of extraneous hardware from the MoBo,  including  disabling every built-in peripheral that you can through BIOS  if it is  not absolutely required to boot ESXi.  (I think you can even  remove or  disable the NIC.)

I really dont have any peripherals installed on my mobo. All it basically has are the dimms. But i will try to look around in the bios some more to see what i can disable.

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CarWolff
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>IIRC, your motherboard does not support "single dimm in slot2"  configuration. If you use only one dimm, it must be always in slot1. Try  to test both dimms in slot1 to see if they are correctly recognised...

That is exactly what is happening on my system. So I can assume that the motherboard is working fine.

I have tested both dimms in slot1 and they both got recognized in the bios as having 8 gigs each.

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dariusd
VMware Employee
VMware Employee

Could you grab /var/log/boot.gz from within ESXi on the affected system, while it's got 16 GBytes installed (and showing in BIOS) and only reporting < 8 GBytes of RAM in ESXi?  If you could attach it to a reply (just use the Browse... button when composing your reply), I'll take a look and see what I can figure out.

Thanks,

--

Darius

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CarWolff
Contributor
Contributor

Sorry for taking a while to reply. Been very busy.

Anyway, I wouldn't be able to take out the log on esxi, because what I have done is I had RMA'ed the MoBo. And I am as of right now, waiting for the replacement to come in.

The reason behind all that was that, I did some more troubleshooting on my build, and found out that with ANY operating system I install on it, only 7.5 GB is usable.

I had installed Server 2008 r2 and Windows 7 64bit, and when I go to computer > sys properties, it says that I have 16GB but only 7.5GB usable. So I went a little further on my troubleshooting and went ahead and pulled my other pair of ddr3 2x4GB on my other RIG which I know for SURE that everything was working fine. This confirmed that the OS wasn't the cause of all this issue.

I then swapped out the 2x8GB and installed the 2x4GB memory modules on this server I was building. And guess what? In windows 7 and server 2008 it still showed that I had 4GB but ONLY 2GB usable. So I think that there's something wrong with the motherboard. That's the reason I shipped it out.

OR could it be possible that the processor is bad? What do you guys think?

I guess I'll never know untill I get the replacement motherboard and test it out again.

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Gnome007
Contributor
Contributor

Hi CarWolf,

please check for the latest bios. In my case I had also 8gb modules and I was also only able to use half of the ram.

After a simple bios update the full ram was usable.

Please try.

Cheers

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