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Old 11-10-2008, 01:02 PM   #1
rsmccain
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Registered: Apr 2004
Location: Louisiana
Distribution: SUSE
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Linux only sees 3GB of 4GB memory installed


We had four 512 DIMMs in a Dell PowerEdge 2850 = 2 GB RAM.

Wee needed to upgrade to 4 GB, so we removed those four and put in two 2 GB, but running top or /proc/meminfo only shows 3GB. dmidecode shows 4GB
its SLES 10 SP1; kernel = 2.6.16.46-0.12-smp. any ideas?

--

dmidecode snipped output:

Handle 0x1000, DMI type 16, 15 bytes.
Physical Memory Array
Location: System Board Or Motherboard
Use: System Memory
Error Correction Type: Multi-bit ECC
Maximum Capacity: 16 GB
Error Information Handle: Not Provided
Number Of Devices: 6

Handle 0x1100, DMI type 17, 27 bytes.
Memory Device
Array Handle: 0x1000
Error Information Handle: Not Provided
Total Width: 72 bits
Data Width: 64 bits
Size: 2048 MB
Form Factor: DIMM
Set: 1
Locator: DIMM1_A
Bank Locator: Not Specified
Type: DDR2
Type Detail: Synchronous
Speed: 400 MHz (2.5 ns)
Manufacturer: AD00000000000000
Serial Number: 0000301D
Asset Tag: 010742
Part Number: HYMP525R72BP4-E3

Handle 0x1101, DMI type 17, 27 bytes.
Memory Device
Array Handle: 0x1000
Error Information Handle: Not Provided
Total Width: 72 bits
Data Width: 64 bits
Size: 2048 MB
Form Factor: DIMM
Set: 1
Locator: DIMM1_B
Bank Locator: Not Specified
Type: DDR2
Type Detail: Synchronous
Speed: 400 MHz (2.5 ns)
Manufacturer: AD00000000000000
Serial Number: 0000201F
Asset Tag: 010742
Part Number: HYMP525R72BP4-E3

Handle 0x1102, DMI type 17, 27 bytes.
Memory Device
Array Handle: 0x1000
Error Information Handle: Not Provided
Total Width: 72 bits
Data Width: 64 bits
Size: No Module Installed
Form Factor: DIMM
Set: 2
Locator: DIMM2_A
Bank Locator: Not Specified
Type: DDR2
Type Detail: Synchronous
Speed: 400 MHz (2.5 ns)
Manufacturer:
Serial Number:
Asset Tag:
Part Number:

Handle 0x1103, DMI type 17, 27 bytes.
Memory Device
Array Handle: 0x1000
Error Information Handle: Not Provided
Total Width: 72 bits
Data Width: 64 bits
Size: No Module Installed
Form Factor: DIMM
Set: 2
Locator: DIMM2_B
Bank Locator: Not Specified
Type: DDR2
Type Detail: Synchronous
Speed: 400 MHz (2.5 ns)
Manufacturer:
Serial Number:
Asset Tag:
Part Number:

Handle 0x1104, DMI type 17, 27 bytes.
Memory Device
Array Handle: 0x1000
Error Information Handle: Not Provided
Total Width: 72 bits
Data Width: 64 bits
Size: No Module Installed
Form Factor: DIMM
Set: 3
Locator: DIMM3_A
Bank Locator: Not Specified
Type: DDR2
Type Detail: Synchronous
Speed: 400 MHz (2.5 ns)
Manufacturer:
Serial Number:
Asset Tag:
Part Number:

Handle 0x1105, DMI type 17, 27 bytes.
Memory Device
Array Handle: 0x1000
Error Information Handle: Not Provided
Total Width: 72 bits
Data Width: 64 bits
Size: No Module Installed
Form Factor: DIMM
Set: 3
Locator: DIMM3_B
Bank Locator: Not Specified
Type: DDR2
Type Detail: Synchronous
Speed: 400 MHz (2.5 ns)
Manufacturer:
Serial Number:
Asset Tag:
Part Number:


/proc/meminfo output:

MemTotal: 3107576 kB
MemFree: 133124 kB
Buffers: 319604 kB
Cached: 2291024 kB
SwapCached: 32 kB
Active: 2145408 kB
Inactive: 661048 kB
HighTotal: 2227972 kB
HighFree: 14704 kB
LowTotal: 879604 kB
LowFree: 118420 kB
SwapTotal: 524280 kB
SwapFree: 517968 kB
Dirty: 1736 kB
Writeback: 0 kB
AnonPages: 196128 kB
Mapped: 633380 kB
Slab: 154204 kB
CommitLimit: 2078068 kB
Committed_AS: 4512240 kB
PageTables: 4976 kB
VmallocTotal: 114680 kB
VmallocUsed: 3676 kB
VmallocChunk: 110792 kB
HugePages_Total: 0
HugePages_Free: 0
HugePages_Rsvd: 0
Hugepagesize: 4096 kB


---

snipped hwinfo shows only 3 of 4 GB being used:

<6>Memory: 3102616k/4194304k available (1643k kernel code, 41400k reserved, 7
47k data, 196k init, 2227972k highmem)
 
Old 11-10-2008, 01:08 PM   #2
Quakeboy02
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Distribution: Debian Squeeze 2.6.32.9 SMP AMD64
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I ran into this problem recently and was advised that I needed a PAE enabled kernel. If you're compiling your own kernels, you need to set the memory to HIGHMEM_64G. That enables PAE. The HIGHMEM_4G kernels cannot have PAE for some reason. Anyway, like you I was stuck at 3G until I recompiled my kernel. I don't know which kernel you have to download to get the PAE kernel for SUSE.
 
Old 11-10-2008, 01:35 PM   #3
rsmccain
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Registered: Apr 2004
Location: Louisiana
Distribution: SUSE
Posts: 154

Original Poster
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Quote:
Originally Posted by Quakeboy02 View Post
I ran into this problem recently and was advised that I needed a PAE enabled kernel. If you're compiling your own kernels, you need to set the memory to HIGHMEM_64G. That enables PAE. The HIGHMEM_4G kernels cannot have PAE for some reason. Anyway, like you I was stuck at 3G until I recompiled my kernel. I don't know which kernel you have to download to get the PAE kernel for SUSE.
Interesting. I didn't think there would be an issue until I hit 4gb. thanks
 
Old 11-11-2008, 01:44 PM   #4
arizonagroovejet
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Registered: Jun 2005
Location: England
Distribution: SLED, openSUSE
Posts: 1,009

Rep: Reputation: 171Reputation: 171
There is a package in SLES 10 callled kernel-bigsmp - try installing that instead of kernel-smp. In SLED 10 I have found that it is necessary to use kernel-bigsmp to recognise 4GB of memory even though the package description for kernel-smp says "this kernel supports up to 4GB of main memory.". SLES and SLED are essentially the same thing, just slightly different packages included.

SLES 10 SP1 is either no longer supported by Novell or very close, as in a couple of weeks, of no longer being supported. I forget the exact date support ceases but I think it's in November. You should have updated to SP2 by now.
 
Old 11-12-2008, 05:44 AM   #5
peeths003
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Distribution: Fedora 12 i686, Debian 5.0.1 i686, Fedora 14 x86_64, Debian Lenny 5.0.1x86_64 and CentOS_5.4_x86-64
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I read somewhere that .... 32 bit architecture support only upto 3 GB of RAM. i have a 64bit and it take my whole 4 GB RAM , i have not tried installing 32 bit into that machine ......

I am not sure whether this was helpful .........
 
  


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