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error has occurred in L2C Data Cache at location 0x347.

Answered Question
Jul 9th, 2013
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Hello Experts,


can someone please clarify on below error message. this rasid on a cisco 2921 router.


%PLATFORM-5-ECC_MSG: A corrected single bit error has occurred in L2C Data Cache at location 0x347.



thanks alot in advance.

Hardi

Correct Answer by Ivan Shirshin about 4 years 1 month ago

Hello Hardi,


1. The issue could be also transient. Note that this platform tries to fix the parity error in SW by default to avoid service impact. Replacement is needed if such errors are reoccurring.

Errors are in DRAM but in some cases DRAM may be damaged due to HW issues in the router memory slot. In such occurrence router chassis should be replaced as well.


2. Parity errors are data corruptions happenning due to the way DRAM technology is.


These single bit errors occur when a bit in a data word changes unexpectedly due to external events (thus causing for example a zero to spontaneously change to a one). A parity error can happen in all type of RAM, regardless of the manufacturing. There are two kinds of parity errors: 

Soft parity errors

These errors occur when an energy level within the chip (for example, a one or a zero) changes, most often due to radiation. When referenced by the CPU, such errors cause the system to crash. In case of a soft parity error, there is no need to swap the board or any of the components.


Hard parity errors

These errors occur when there is a chip or board failure that corrupts data. In this case, you need to re-seat or replace the affected component, which usually involves a memory chip swap or a board swap.


At the first occurrence it is not possible to distinguish between a soft or hard parity errors. From experience, most parity occurrences are soft parity errors, and you can usually dismiss them. Studies have shown that soft parity errors are 10 to 100 times more frequent than hard parity errors. Therefore, Cisco highly recommends you to wait for a second parity error on that particular affected component before you replace anything. This greatly reduces the impact on your network.


To learn more about Parity Errors please check the following CCO documentations:

https://www.cisco.com/en/US/products/hw/routers/ps341/products_tech_note09186a0080094793.shtml

http://www.cisco.com/en/US/products/hw/routers/ps167/products_tech_note09186a0080094340.shtml


Kind Regards,
Ivan Shirshin

**Please grade this post if you find it useful.

Correct Answer by skapadi about 4 years 1 month ago

Hi Hardi,


Cisco error decoder says :


Parity errors are a single bit error has occurred in memory and is corrected. The system will operate normally, and the operation can continue without interruption. However, if the error happens very frequently at the same location, it may

be a hardware defect and replacement will resolve the issue.


If you are seeing the error message frequently at the same address than RMA would be best option. If you are seeing this error once in awhile than its transient issue.



This is hardware issue and can be resolved by replacing DRAM. Please contact Cisco TAC if error you are seeing these error continously.


HTH,

Subhash

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Correct Answer
skapadi Tue, 07/09/2013 - 04:26
User Badges:
  • Cisco Employee,

Hi Hardi,


Cisco error decoder says :


Parity errors are a single bit error has occurred in memory and is corrected. The system will operate normally, and the operation can continue without interruption. However, if the error happens very frequently at the same location, it may

be a hardware defect and replacement will resolve the issue.


If you are seeing the error message frequently at the same address than RMA would be best option. If you are seeing this error once in awhile than its transient issue.



This is hardware issue and can be resolved by replacing DRAM. Please contact Cisco TAC if error you are seeing these error continously.


HTH,

Subhash

Hardi Ahmed Tue, 07/09/2013 - 04:43
User Badges:
  • Gold, 750 points or more

Hello  Dear,


thanks alot for your prompt reply.


I have below questions:

1- this issue will resolving by replaicing DRAM? or there is another part else should be replacing?

2- what make this issue  to raise?



Many thanks and kindest regards,

Hardi

Correct Answer
Ivan Shirshin Tue, 07/09/2013 - 05:16
User Badges:
  • Cisco Employee,

Hello Hardi,


1. The issue could be also transient. Note that this platform tries to fix the parity error in SW by default to avoid service impact. Replacement is needed if such errors are reoccurring.

Errors are in DRAM but in some cases DRAM may be damaged due to HW issues in the router memory slot. In such occurrence router chassis should be replaced as well.


2. Parity errors are data corruptions happenning due to the way DRAM technology is.


These single bit errors occur when a bit in a data word changes unexpectedly due to external events (thus causing for example a zero to spontaneously change to a one). A parity error can happen in all type of RAM, regardless of the manufacturing. There are two kinds of parity errors: 

Soft parity errors

These errors occur when an energy level within the chip (for example, a one or a zero) changes, most often due to radiation. When referenced by the CPU, such errors cause the system to crash. In case of a soft parity error, there is no need to swap the board or any of the components.


Hard parity errors

These errors occur when there is a chip or board failure that corrupts data. In this case, you need to re-seat or replace the affected component, which usually involves a memory chip swap or a board swap.


At the first occurrence it is not possible to distinguish between a soft or hard parity errors. From experience, most parity occurrences are soft parity errors, and you can usually dismiss them. Studies have shown that soft parity errors are 10 to 100 times more frequent than hard parity errors. Therefore, Cisco highly recommends you to wait for a second parity error on that particular affected component before you replace anything. This greatly reduces the impact on your network.


To learn more about Parity Errors please check the following CCO documentations:

https://www.cisco.com/en/US/products/hw/routers/ps341/products_tech_note09186a0080094793.shtml

http://www.cisco.com/en/US/products/hw/routers/ps167/products_tech_note09186a0080094340.shtml


Kind Regards,
Ivan Shirshin

**Please grade this post if you find it useful.

Hardi Ahmed Tue, 07/09/2013 - 08:31
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  • Gold, 750 points or more

hello dears,


OK, thanks alot for your prompt reply and support.


my last question is; what will happen if I faced this issue in a very frequent, what will happen to the rpouter?

as I undrestood from above information the router should stop of working by then cisco open a TAC with you for trouble shooting.


thanks alot in advance.

hardi

Ivan Shirshin Wed, 07/10/2013 - 21:32
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  • Cisco Employee,

Hello Hardi,


With frequent errors like this system may experience higher CPU utilization (as CPU would need to correct the errors) and with a very high rate of errors the auto-recovery may not help and the router would crash.

With a small rate of errors there is no impact but it is recommended to open Cisco TAC case for troubleshooting.


Kind Regards,
Ivan Shirshin

**Please grade this post if you find it useful.

Hardi Ahmed Tue, 07/16/2013 - 10:48
User Badges:
  • Gold, 750 points or more

Hello Ivan,


till now this error for one time apperared on my router log. do I have to open a TAC case with Cisco now?


many thnaks in advance,

Hardi

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