Find in Linux if your installed RAM is ECC

By | October 19, 2017

Sometimes really simple questions are hard to answer. One day I got the question from a coworker: “How do I know if some installed RAM is ECC or not”.
The easiest way is to use dmidecode command that dumps in Linux all the system characteristics. But because I had no idea how to see if a RAM chip is ECC or not I made a comparison.

STEP 1: List the memory specs on a server populated with ECC memory

STEP 2: List the memory specs on a machine populated with NON ECC memory

We can see in the first dump that the motherboard supports ECC:

and in the second ECC is not supported. This is what I expected as the first machine is a HP Server and the second is a Dell laptop

But looking at the individual DIMM entries from the dumps (2 DIMMs on HP server and 2 DIMMs on the laptop) there is no explicit ECC or Error Correction Type Entry field.

The secret entry that makes the difference is this:

On HP server DIMM1:

On the Dell Laptop DIMM1:

As you can see on the ECC DIMM the reported Total Width is 72 bits and on the non ECC the reported Total Width is 64 bits. So this is our cue. In case of ECC memory besides the normal 64 bits (Data Width) we have some extra 8 bits for Error Correction.

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