[CentOS] ECC RAM Error

John R Pierce pierce at hogranch.com
Thu Oct 11 20:47:59 UTC 2007

Peter Arremann wrote:
> On Thursday 11 October 2007, John R Pierce wrote:
>> Peter Arremann wrote:
>>> On Thursday 11 October 2007, Centos wrote:
>>>> The ECC errors only happens when I am transferring data from other
>>>> storage to this one that we get error.
>>>> it only happens when it is writing data to it.
>> What do you mean by "transferring data from other storage to this one"
>> ?    These are main memory (RAM) ECC errors and have nothing to do with
>> disk storage, networking, or anything else.
>> and, 'writing data to it', its not clear what the 'it' is referring to.
> Storage - anything that can store data. ECC is a generic term and covers all 
> kinds of checksumming algorithms. I was talking pretty generic - don't care 
> if ram, caches, nand-flash, ficon or anything else. 
> I was trying to get across that its hard to pinpoint where your bits flipped - 
> in the storage device, on the transmission there or back. 
if they flipped in a disk storage device, you would have gotten a disk 
storage related error, typically reported as a "CRC" error even tho 
modern disks haven't actually used CRC since the 80s.  

systems don't tend to transmit and store the ECC across different device 

if they had been read off the disk in a 'flipped' state, then they would 
have been written to RAM just as they were read, and the RAM would have 
created its own ECC on the 'wrong' data quite happily.

anyways, the error in question...

 > : EXCEPTION: ECC Error Interrupt (Two or more Bit Error)
 > 0C18:00020001 0C68:00000000 Lcause:74630001 Lerr:1C855F82

is almost certainly a RAM ECC error, so I was asking the original poster 
just what he meant by 'transferring data from other storage to this one' 
as it sounded like he was thinking in terms of overall server operation 
rather than the specific component level.

if he was talking about copying files from one disk to another, then 
that data has to be read from the source disk and written into ram, then 
read back from ram and written to the other device.  in fact, its 
possibly been copied a few times in ram in the process too, so talking 
about transfering between storage really isn't very helpful here.

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