This article clarifies that the "ECC errors uncorrectable 6301 correctable 6301 chA 1 chB 0" errors that may be seen on MX Series routers will not have any service impact if the number of correctable and uncorrectable is the same, and indicates what must be done to clear the error.

The following messages may be output continuously:

Jan  4 02:39:06.559  GURO3F-WNAT-3-RE0 : %USER-3: (FPC Slot 9, PIC Slot 3)  ms93 kernel: svcs_ms2_ddr_mon: ECC errors uncorrectable 6301 correctable 6301 chA 1 chB 0
Jan  4 02:40:07.487  GURO3F-WNAT-3-RE0 : %USER-3: (FPC Slot 9, PIC Slot 3)  ms93 kernel: svcs_ms2_ddr_mon: ECC errors uncorrectable 6361 correctable 6361 chA 1 chB 0
Jan  4 02:41:08.214  GFURO3F-WNAT-3-RE0 : %USER-3: (FPC Slot 9, PIC Slot 3)  ms93 kernel: svcs_ms2_ddr_mon: ECC errors uncorrectable 6421 correctable 6421 chA 1 chB 0
Jan  4 02:42:09.140  GURO3F-WNAT-3-RE0 : %USER-3: (FPC Slot 9, PIC Slot 3)  ms93 kernel: svcs_ms2_ddr_mon: ECC errors uncorrectable 6481 correctable 6481 chA 1 chB 0

The error checking and correction (ECC) process has the important function of error detection and recovery on RLDRAM. Although the process varies in MPC types, the fundamental mechanism is the same. In this process, data is stored as 8 bits in RLDRAM block's cell blank, which is used to detect and correct 1-bit errors and detect double/multi-bit errors.

ms93 kernel: svcs_ms2_ddr_mon: ECC errors uncorrectable 61 correctable 61 chA 1 chB 0

If you look closely at the message log with the ECC error, you see that the number of uncorrectable and correctable errors is the same. If the number of uncorrectable and correctable errors is the same in the ECC error message, it means that the errors being detected can actually be corrected and are immediately corrected as well. Therefore, there will be no service impact due to these errors.

ECC errors uncorrectable 6301 correctable 6301 chA 1 chB 0

Any 2-bit/multi-bit uncorrectable error as shown below, however, would be deemed fatal and the error data would not be sent to the pipeline logic. Two-bit error corrections by the ECC may not be reliable and the recommendation would be to RMA the FPC as soon as possible.

xm_cpq[0]_intr_status_ecc_2bit_

There should not be any service impact due to this error. To clear this error, reboot or re-seat the FPC by using the following command:

request chassis fpc restart slot <fpc-slot#>

If the problem persists, contact Support for further assistance.