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CentOS 7 reporting 1/6 of total ram installed on system

Posted: 2019/08/11 22:41:16
by ember2inferno

I'd like to start by saying I am new to Nix operating systems and this is my first time posting on a forum of this nature. I'm trying to learn as much as I can and I would greatly appreciate anyone providing help or pointing me in the right direction. I hope that I am using this forum in the correct manner, apologies if I made a mistake.

I am configuring a lab environment with CentOS 7 as the host operating system (bare metal) on a Dell Poweredge R710 server. It is intended to by used as a hyper-visor for various Nix operating systems using vmware 15 pro. Previously I had windows server 2016 installed with system center but wanted to transition to nix as I am starting to like the operating systems much better. My issue is that after installation, my CentOS host is only showing 8GB of ram on the system even though there is currently 48GB installed. Commands like free and cat /proc/meminfo only show 8GB but running lshw clearly shows 48GB installed.

This is an entirely fresh install of Centos 7. The only additional software on the system is vmware 15 pro. There are no installed VMs.

Linux xx 3.10.0-957.27.2.el7.x86_64 #1 SMP Mon Jul 29 17:46:05 UTC 2019 x86_64 x86_64 x86_64 GNU/Linux

free -m
total used free shared buff/cache available
Mem: 7797 2063 2276 24 3458 5250
Swap: 15361 0 15361

cat /proc/meminfo
MemTotal: 7984968 kB
MemFree: 2331096 kB
MemAvailable: 5376900 kB
Buffers: 1972 kB
Cached: 2994924 kB
SwapTotal: 15730684 kB
SwapFree: 15730684 kB

dmesg |egrep e820
[ 0.000000] e820: BIOS-provided physical RAM map:
[ 0.000000] BIOS-e820: [mem 0x0000000000010000-0x000000000009ffff] usable
[ 0.000000] BIOS-e820: [mem 0x0000000000100000-0x00000000ce777fff] usable
[ 0.000000] BIOS-e820: [mem 0x00000000ce778000-0x00000000ce977fff] reserved
[ 0.000000] BIOS-e820: [mem 0x00000000ce978000-0x00000000cea76fff] usable
[ 0.000000] BIOS-e820: [mem 0x00000000cea77000-0x00000000cea7bfff] ACPI NVS
[ 0.000000] BIOS-e820: [mem 0x00000000cea7c000-0x00000000ceafbfff] ACPI data
[ 0.000000] BIOS-e820: [mem 0x00000000ceafc000-0x00000000cef21fff] usable
[ 0.000000] BIOS-e820: [mem 0x00000000cef52000-0x00000000cef78fff] usable
[ 0.000000] BIOS-e820: [mem 0x00000000cf379000-0x00000000cf38efff] reserved
[ 0.000000] BIOS-e820: [mem 0x00000000cf38f000-0x00000000cf3cdfff] ACPI data
[ 0.000000] BIOS-e820: [mem 0x00000000cf3ce000-0x00000000cfffffff] reserved
[ 0.000000] BIOS-e820: [mem 0x00000000e0000000-0x00000000efffffff] reserved
[ 0.000000] BIOS-e820: [mem 0x00000000fe000000-0x00000000ffffffff] reserved
[ 0.000000] BIOS-e820: [mem 0x0000000100000000-0x000000022fffffff] usable
[ 0.000000] e820: update [mem 0xcc458018-0xcc45b057] usable ==> usable
[ 0.000000] e820: update [mem 0xcc42f018-0xcc457857] usable ==> usable
[ 0.000000] e820: update [mem 0xcc426018-0xcc42e057] usable ==> usable
[ 0.000000] e820: update [mem 0x00000000-0x00000fff] usable ==> reserved
[ 0.000000] e820: remove [mem 0x000a0000-0x000fffff] usable
[ 0.000000] e820: last_pfn = 0x230000 max_arch_pfn = 0x400000000
[ 0.000000] e820: update [mem 0xd0000000-0xffffffff] usable ==> reserved
[ 0.000000] e820: last_pfn = 0xcef79 max_arch_pfn = 0x400000000
[ 0.000000] e820: [mem 0xd0000000-0xdfffffff] available for PCI devices
[ 0.338001] e820: reserve RAM buffer [mem 0xcc426018-0xcfffffff]
[ 0.338003] e820: reserve RAM buffer [mem 0xcc42f018-0xcfffffff]
[ 0.338005] e820: reserve RAM buffer [mem 0xcc458018-0xcfffffff]
[ 0.338007] e820: reserve RAM buffer [mem 0xce778000-0xcfffffff]
[ 0.338009] e820: reserve RAM buffer [mem 0xcea77000-0xcfffffff]
[ 0.338011] e820: reserve RAM buffer [mem 0xcef22000-0xcfffffff]
[ 0.338013] e820: reserve RAM buffer [mem 0xcef79000-0xcfffffff]

description: System Memory
physical id: 1000
slot: System board or motherboard
size: 48GB
capabilities: ecc
configuration: errordetection=multi-bit-ecc

Following other forums that I could find on the issue, a lot of questions were asked about CentOS only showing about 95% of installed RAM due to kernel ram reservations. This clearly isn't my problem as my machine is only appearing to use 1/6 of installed RAM. The other question I commonly found was people asking a similar question about CentOS showing only half of available FREE RAM. Since my question is regarding RAM in general and not simply free RAM this was also not helpful for my situation. It is very likely that I am simply misunderstanding something so if that is the case I'd be very thankful to learn the reality of the issue I am facing. If anyone has any thoughts I'd be very appreciative to hear and consider them.

Thanks everyone,

Re: CentOS 7 reporting 1/6 of total ram installed on system

Posted: 2019/08/11 22:49:13
by TrevorH
Where does VMWare come into this? Is your CentOS system a VMWare guest? Or installed on the bare metal?

Re: CentOS 7 reporting 1/6 of total ram installed on system

Posted: 2019/08/11 22:51:17
by ember2inferno

CentOS is installed on bare metal. The intent of the machine is to be used as a hyper-visor to host other machines on.

Re: CentOS 7 reporting 1/6 of total ram installed on system

Posted: 2019/08/12 08:34:18
by TrevorH
Yes but VMWare is a standalone thing and doesn't run on top of another operating system. If you aim to use VMWare then it wants control of the bare metal.

Re: CentOS 7 reporting 1/6 of total ram installed on system

Posted: 2019/08/15 01:19:43
by ember2inferno

I really appreciate the response. I'm afraid I don't quite understand your statement. My understanding is that VMWare is a software application that runs on top of whichever operating system is installed. When configuring VMs with VMWare (or any hypervisor), you allocate hardware (processors, ram, disk space, etc.) to that virtual machine and it is reserved exclusively for that operating system. Am I mistaken about this information? Additionally, my issue is that while I could install VMWare on my CentOS 7 install, since CentOS is only registering that there is 8GB of ram on the system, I am afraid that assigning ram to my virtual machines will eat up my usable ram for CentOS instead of using the other 40GB of ram installed on the server that CentOS is not registering for some reason. I guess for my question in general I really am trying to learn why CentOS is only registering 8/48GB of my ram and how I would go about fixing that issue.

I really appreciate the help,

Re: CentOS 7 reporting 1/6 of total ram installed on system

Posted: 2019/08/15 08:44:13
by TrevorH
VMWare is a hypervisor that wants to control the bare metal. It doesn't run on top of another operating system unless you're using the toy "VMWare Player".

Re: CentOS 7 reporting 1/6 of total ram installed on system

Posted: 2019/08/15 19:11:02
by hje
Hey Ash,

I think you got some things wrong with the description of your problem.
There are two types of hypervisors, bare-metal - or type 1 - like VMWare ESX/ESXi, MS HyperV Server, Citrix, Proxmox etc and hosted - or type 2 - like the VMWare Workstation Pro what you are talking about.
So your problem is you installed CentOS 7 on a pc with 48 gigs om memory and it only shows 8 gigs in CentOS, right? What are your BIOS settings - does it show all 48 gigs there? And why don't you use a real bare-metal hypervisor would be way more efficient for your hardware usage.

Re: CentOS 7 reporting 1/6 of total ram installed on system

Posted: 2019/08/16 13:09:23
by maikcat

Can you please the output of:

dmidecode -t chassis
numactl -H
cat /proc/cmdline



Re: CentOS 7 reporting 1/6 of total ram installed on system

Posted: 2019/08/16 13:44:54
by TrevorH
Also what version of the BIOS is installed? dmidecode -t BIOS

Re: CentOS 7 reporting 1/6 of total ram installed on system

Posted: 2019/08/17 20:05:57
by ember2inferno

Thank you for helping me clarify. Apologies if I miss-communicated my original problem. I have 48GB installed on the server and only 8 appearing in CentOS.

UPDATE: I checked out my BIOS settings and it is only reporting 8GB of memory. What the heck. Ok, sorry guys. This is apparently not a CentOS issue, but a bios/MB issue it would appear. I really appreciate the help up until this point. If anyone would be willing to help point me in the right direction I would greatly appreciate that as well. I think it just really confused me that lshw reported the full 48GB?


I ran the commands requested and it appears they aren't registering anything other than 8GB as well.

dmidecode -t chassis
# dmidecode 3.1
Getting SMBIOS data from sysfs.
SMBIOS 2.6 present.

Handle 0x0300, DMI type 3, 21 bytes
Chassis Information
Manufacturer: Dell Inc.
Type: Rack Mount Chassis
Lock: Present
Version: Not Specified
Serial Number: 5N1QNM1
Asset Tag:
Boot-up State: Safe
Power Supply State: Safe
Thermal State: Safe
Security Status: Unknown
OEM Information: 0x00000000
Height: 2 U
Number Of Power Cords: Unspecified
Contained Elements: 0

numactl -H
available: 2 nodes (0-1)
node 0 cpus: 0 2 4 6 8 10 12 14
node 0 size: 8172 MB
node 0 free: 5423 MB
node 1 cpus: 1 3 5 7 9 11 13 15
node 1 size: 0 MB
node 1 free: 0 MB
node distances:
node 0 1
0: 10 20
1: 20 10

cat /proc/cmdline
BOOT_IMAGE=/vmlinuz-3.10.0-957.27.2.el7.x86_64 root=/dev/mapper/luks-fb356783-538c-4baf-947e-a2039977b2b1 ro crashkernel=auto rd.luks.uuid=luks-fb356783-538c-4baf-947e-a2039977b2b1 rd.luks.uuid=luks-c4732207-5f75-4df8-8a02-6f712f2c6ddf rhgb quiet LANG=en_US.UTF-8


dmidecode -t BIOS
# dmidecode 3.1
Getting SMBIOS data from sysfs.
SMBIOS 2.6 present.

Handle 0x0000, DMI type 0, 24 bytes
BIOS Information
Vendor: Dell Inc.
Version: 6.4.0
Release Date: 07/23/2013
Address: 0xF0000
Runtime Size: 64 kB
ROM Size: 4096 kB
ISA is supported
PCI is supported
PNP is supported
BIOS is upgradeable
BIOS shadowing is allowed
Boot from CD is supported
Selectable boot is supported
EDD is supported
Japanese floppy for Toshiba 1.2 MB is supported (int 13h)
5.25"/360 kB floppy services are supported (int 13h)
5.25"/1.2 MB floppy services are supported (int 13h)
3.5"/720 kB floppy services are supported (int 13h)
8042 keyboard services are supported (int 9h)
Serial services are supported (int 14h)
CGA/mono video services are supported (int 10h)
ACPI is supported
USB legacy is supported
BIOS boot specification is supported
Function key-initiated network boot is supported
Targeted content distribution is supported
BIOS Revision: 6.4

Handle 0x0D00, DMI type 13, 22 bytes
BIOS Language Information
Language Description Format: Long
Installable Languages: 1
Currently Installed Language: en|US|iso8859-1

If anyone has any further suggestions on how to look into this I'd really appreciate getting pointed in the right direction.

Thanks all,