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i0
n00b
Joined: 11 Oct 2006
Posts: 46
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 Posted: Thu Jun 26, 2008 8:30 am Post subject: Memory question |
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Hi
Weird thing.
I have a Intel Xeon machine with Tyan Tempest i5000VS S5372 motherboard and 2 Kingston ECC FB/DIMM modules.
Problem is that memtest86 does not show that this is ECC memory (even when i try to switch ecc on from memtest86 configuration).
Dmidecode does not show that system has ecc memory.
| Code: | titania ~ # dmidecode --type memory
# dmidecode 2.9
SMBIOS 2.4 present.
Handle 0x001E, DMI type 16, 15 bytes
Physical Memory Array
Location: System Board Or Motherboard
Use: System Memory
Error Correction Type: None
Maximum Capacity: 64 GB
Error Information Handle: Not Provided
Number Of Devices: 2
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Answer about this issue from Tyan says:
| Quote: | This is not possible. If you need to switch off ECC, you can only do that on
platforms, which use DDR 1 or 2 Registered ECC modules. On FBDIMM modules,
there is no possibility to disable ECC.
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So i guess, both (memtest86, dmidecode) lie to me?
Any ideas? |
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manaka
Apprentice
Joined: 23 Jul 2007
Posts: 178
Location: Spain
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| Posted: Thu Jun 26, 2008 9:06 pm Post subject: |
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Have tested many servers with ECC memory... In all cases, memtest86 showed ECC support as disabled... I think (but I am not completely sure) memtest86 disables ECC if supported by the chipset... So it always shows ECC support as disabled...
As for dmidecode, it reports the information that was written by the motherboard vendor... Some vendors or motherboard models seem to provide more accurate descriptions than others... So I think that dmidecode is not lying, it's reading wrong information...
Here is the dmidecode output on one of my servers... Seems accurate in this case... 
| Code: |
dmidecode --type memory
# dmidecode 2.9
SMBIOS 2.34 present.
Handle 0x0019, DMI type 16, 15 bytes
Physical Memory Array
Location: System Board Or Motherboard
Use: System Memory
Error Correction Type: Single-bit ECC
Maximum Capacity: 16 GB
Error Information Handle: Not Provided
Number Of Devices: 8
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_________________
Javier Miqueleiz
"Listen to your heart. It knows all things, because it came from the Soul of the World, and it will one day return there." |
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i0
n00b
Joined: 11 Oct 2006
Posts: 46
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| Posted: Thu Jun 26, 2008 9:32 pm Post subject: |
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| manaka wrote: | Have tested many servers with ECC memory... In all cases, memtest86 showed ECC support as disabled... I think (but I am not completely sure) memtest86 disables ECC if supported by the chipset... So it always shows ECC support as disabled...
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Yes, memtest86 should disable ECC for testing (correct me if i am wrong) because there would be not much sense to test memory module if it corrects errors, however ECC can be enabled (correct me again, if i'm wrong) during memory testing.
One of other servers, while testing with memtest86 i was able to switch ECC on during test and also dmidecode shows that memory has ECC.
| Code: | # dmidecode 2.9
SMBIOS 2.3 present.
Handle 0x002B, DMI type 16, 15 bytes
Physical Memory Array
Location: System Board Or Motherboard
Use: System Memory
Error Correction Type: Single-bit ECC
Maximum Capacity: 12 GB
Error Information Handle: Not Provided
Number Of Devices: 8
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In this problematic server's BIOS there is an option about ECC correction type, (single, dual, both), in default it is Single bit, and there is no option to switch ECC off (MB makers are right on that part). What puzzles me is, how can i actually believe (yes, i'm really paranoid ) that there is an ECC memory?
Extend this situation to any other product.
Like: how can you know if an product has a feature if all methods say it is not there and only thing that says that this feature is there is manufacturer/seller.
Very weird. |
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NeddySeagoon
Administrator
Joined: 05 Jul 2003
Posts: 55162
Location: 56N 3W
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| Posted: Thu Jun 26, 2008 9:39 pm Post subject: |
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i0,
dmidecode tells you nothing about your memory.
It reads a piece of the BIOS ROM space that is supposed to descrive the RAM but more often than not, does not.
Read the SPD PROMs on your DIMMS
You need kernel support for i2c on your chipset
and the kernel eeprom module which depends on i2c.
Both those things can be modules.
After that you need lm-sensors but it does not need to be set up.
lm-sensors provides a script called decode-dimms.pl which reads the SPD
content on each RAM stick.
_________________
Regards,
NeddySeagoon
Computer users fall into two groups:-
those that do backups
those that have never had a hard drive fail. |
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i0
n00b
Joined: 11 Oct 2006
Posts: 46
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| Posted: Thu Jun 26, 2008 9:46 pm Post subject: |
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Thanx, NeddySeagoon
I look into that, and post results here.
Thanx, again.
i0 |
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