When a single-bit error (SBE) and/or multi-bit error (MBE) is reported on one or more memory DIMM locations, the cause might not be down to the DIMM itself, so some simple troubleshooting will need to be performed to determine where exactly the fault lies. See Figure 1 (English Only) for an example of memory errors appearing in the iDRAC interface on an R715.
Figure 1: Memory errors as displayed in iDRAC 6 logs
Isolating memory issues involves swapping memory DIMMs into different memory sockets, channels, banks and controllers. There are several ways you can swap the DIMMs around to narrow down the fault. You might need to use more than one of these methods to pinpoint the faulty DIMM or Socket. Below you will find a representation of these methods. To make the explanations easy, we will assume the faulty DIMM is A1 or one of the set marked in Blue in the illustrations.
Swapping DIMMs in groups (by Channel or Bank) rather than individually is the best method to identify the failed DIMM or DIMMs
Once a group of DIMMs has been identified to contain the failed DIMM or DIMMs, then moving single DIMMs can be used to identify which DIMM(s) has failed
Swapping DIMM A1 (marked in blue) with DIMM A9 (Marked in red) to try the DIMM in a different memory channel and bank
Figure 2: Swapping DIMM A1 with DIMM A9
Swapping DIMM A1 (marked in blue) with DIMM B1 (marked in red) which will put the DIMM on an altogether different memory controller (CPU).
Figure 3: Swapping DIMM A1 with DIMM B1
Swapping the whole bank of DIMMS (A1, A2, A3 - marked blue) with another bank (B1, B2, B3 - marked red) will test the whole bank of DIMMs in a new bank, on a new memory controller.
Figure 4: Swapping DIMMs A1, A2, A3 with DIMMs B1, B2, B3
Swapping a whole channel of DIMMs (A1, A4, A7 - marked blue) with another channel (B1, B2, B3 - marked red) will test the whole channel of DIMMs in a new channel, and on a new memory controller.
Figure 5: Swapping DIMMs A1, A4, A7 with DIMMs B1, B4, B7
As a general rule, DIMM errors tend to follow the DIMMs identified in the errors. For example with a SBE reporting on DIMM A1, swapping this DIMM with a different DIMM will result in one of following:
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Article ID: SLN289424
Last Date Modified: 02/07/2017 03:34 AM