Dell r710 Advanced ECC Mode vs Optimized

[ViciousXUSMC]

I have 12x4GB RDIMMS of RAM
Based on the manual I can set this up in optimized or advanced ECC mode.


Advanced ECC Mode This mode uses two MCHs and “ties” them together to emulate a 128-bit data bus DIMM. This is primarily used to achieve a Single Device Data Correction (SDDC) for DIMMs based on x8 DRAM technology. SDDC is supported with x4 based DIMMs in every memory mode. One MCH is completely un-utilized, and any memory installed in this channel will generate a warning message during POST.

Memory Optimized Mode In this mode, the MCHs run independently of each other; for example, one can be idle, one can be performing a write operation, and the other can be preparing for a read operation. Memory may be installed in one, two, or three channels. To fully realize the performance benefit of the memory optimized mode, all three channels per CPU should be populated. This implies that some ‘atypical’ memory configurations, such as 3GB, 6GB, or 12GB, will yield the best performance. This is the recommended mode unless specific RAS features are needed.

Looks like Advanced mode adds an extra layer of protection against memory issues but with a hit in performance.
But on a NAS the performance aspect may not be an issue.

So curious if one mode is better than the other in a FreeNAS setup.

Aka the extra potection is moot based on how ZFS works, or the performance hit is noticeable etc.

 

[joeschmuck]

So your question has nothing to do with FreeNAS, you are just trying to learn something about your motherboard and how it handles RAM. Moved to Off Topic.

It appears that you have already seen this posting since it looks like you cut and pasted your request above so I'm not sure what else you are looking for.

So curious if one mode is better than the other in a FreeNAS setup.

No would be my guess.

all three channels per CPU should be populated. This implies that some ‘atypical’ memory configurations, such as 3GB, 6GB, or 12GB, will yield the best performance.

This is called Tripple Channel Interleve. Most motherboards have dual channel interleve but some (like my home computer) have tripple channel. It is faster than dual channel or single channel but the question is, would you benefit from it? I would of course recommend populating the RAM in banks of three because I prefer to take of every advantage I can.