- ONTAP 9
- Data ONTAP 8
- AFF / FAS platforms
- DIMM Replacement Guide
Choose the appropriate guide based on platform and ONTAP version.
|Platform||System or NVRAM||ONTAP Version||Guide|
||Correctable memory errors reporting in ONTAP versions with static thresholds|
9.1 and higher
||System or NVRAM||9.1 and higher||Correctable memory errors on 62XX, 32XX, 25XX, and 22XX systems in ONTAP|
||System or NVRAM||
Data ONTAP 8 7-Mode
- How to troubleshoot uncorrectable memory errors on AFF and FAS systems
- BIOS updates for memory reliability and the PPR feature
- DIMMs reporting correctable ECC errors should NOT be replaced only because correctable ECC errors are seen in EMS logs or if the “CriticalCECCCountMemErrAlert” system event and AutoSupport messages are seen.
- NetApp storage systems utilize error-correcting code (ECC) memory modules (DIMMs) for both main system memory and NVRAM/NVMEM subsystems. When possible, memory errors are corrected in-flight by the memory subsystem hardware with little to no impact on system performance.
- Previously ONTAP running on AFF/FAS storage systems employed a longstanding policy to alert the system administrator about “excessive” CECC memory errors based on a threshold of 500 errors since the last reboot of the system.
- After extensive analysis of correctable ECC (CECC) memory errors by NetApp and its hardware component vendors, it was determined that CECC memory errors are typically not a good predictor of a system disruption due to uncorrectable ECC (UECC) memory errors – especially with the latest generations of memory controllers and dynamic random-access memory (DRAM).
- Additionally, the CPU cycles used to monitor, log and correct large numbers of memory errors have negligible impact to system performance.
- As a result, NetApp changed the monitoring algorithm for CECC memory errors used by ONTAP on many currently-supported AFF/FAS systems to a dynamic monitoring algorithm, with much higher thresholds configured to trigger the “CriticalCECCCountMemErrAlert” controller Health Monitor alert and corresponding "Health Monitor" AutoSupport message.
- Alerts triggered using the older policy can be considered false positives and should not be taken as an indication for memory replacement as it will result in unnecessary hardware maintenance with no tangible benefits.
- On versions of ONTAP that use the dynamic algorithm, CECC memory errors continue to be periodically logged in ONTAP event logs. However, they are no longer relevant in determining the need for DIMM replacement.
- Correctable ECC errors are not an indicator that an uncorrectable ECC error will occur. Should an uncorrectable memory error occur, it will cause a system disruption (panic). If a system disruption occurs, the panic message will call out the DIMM or DIMMs where the uncorrectable error occurred. For further information see:
- Recent BIOS/LOADER releases for current shipping ONTAP platforms contain memory management enhancements. These updates improve resiliency to uncorrectable ECC errors as well as reduce scenarios where DIMMs can be mapped out during boot such as Bugs 1195242, 1195243, or 1195423. If your BIOS version is not the latest available for your AFF or FAS system, NetApp recommends updating the BIOS to the latest version. Find the latest BIOS/LOADER version for your systems on the System Firmware & Diagnostics Download page.
- JEDEC-standard NVDIMM modules are used in the following platforms:
- AFF A800, AFF A400, AFF A320
- FAS8700, FAS8300