OS shows 484GB RAM, but physical RAM is 512GB

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The OS shows 484GB RAM, but there are 32 DIMMS * 16GB = 512GB RAM. IMM also shows all 32 DIMMs in a normal state. Please assist us in accounting for this disparity. The sosreport is 10MB; I can provide if required.

GS
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Responses

Jamie Bainbridge's picture Red Hat Guru 7257 points
30 June 2015 11:34 PM

Check the physical RAM map which the BIOS provides, eg:

BIOS-provided physical RAM map:
 BIOS-e820: 0000000000000000 - 0000000000099c00 (usable)
 BIOS-e820: 0000000000099c00 - 00000000000a0000 (reserved)
 BIOS-e820: 00000000000f0000 - 0000000000100000 (reserved)
 BIOS-e820: 0000000000100000 - 000000003fffd000 (usable)
 BIOS-e820: 000000003fffd000 - 0000000040000000 (reserved)
 BIOS-e820: 00000000fffbc000 - 0000000100000000 (reserved)

These numbers are bytes in hex.

GS Community Member 30 points
21 July 2015 5:42 PM

How is this query of Ram Map entered, and what does this output mean?

James Radtke's picture Red Hat Guru 7081 points
22 July 2015 1:46 PM

What command are you running to get 484GB as a result?

dmidecode | grep 'Memory Device' | wc -l
dmidecode | grep -A6 'Memory Device' | grep Size
grep ^Mem /proc/meminfo 
free -g
free -m

I included free -g and -m to show how you will observe differences in the presentation of the value.

If dmidecode shows the correct number installed (and correct size for each DIMM) you can look at the "state" of each device

 grep line /sys/devices/system/memory/*/state
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