How to detect ram memory going bad?

How to detect ram memory going bad?

[BP25]

Hello I'm writing to this mailing list as suggested by the btrfs docs. I 
wanted to ask how to detect and mitigate ram memory going bad when using 
BTRFS? Because the 'Hardware Considerations' the BTRFS manual suggest in 
this scenario to run memtest; but this is probs more like right after 
installing new ram. Is there any BTRFS tool, perhaps to run 
periodically, that can help me detect bad ram hence mitigate the 
consequences? There is a webpage called 'Will ZFS and non-ECC RAM kill 
your data?' where it's suggested that ZFS scrub effectively detects bad 
ram (when at least two copies of the same file and/or metadata are 
stored, and I wonder if there are other assumptions here...), but I'm 
new to btrfs and I wonder if the reasoning can be applied to btrfs as 
well, and how effective of a mitigation it would actually provide. OS is 
GNU (Guix) and I think can't use ECC because I suspect my X200 
motherboards wouldn't support it?

Please CC: or BCC: me cause I'm not subscribed.

Re: How to detect ram memory going bad?

[Qu Wenruo]

在 2025/11/20 01:01, BP25 写道:
> Hello I'm writing to this mailing list as suggested by the btrfs docs. I 
> wanted to ask how to detect and mitigate ram memory going bad when using 
> BTRFS? Because the 'Hardware Considerations' the BTRFS manual suggest in 
> this scenario to run memtest; but this is probs more like right after 
> installing new ram.

You should always do a stress test after hardware modification.
And it's always recommended using things like memtest86+ which is a raw 
UEFI payload, with minimal memory reserved, so that almost all RAM can 
be properly tested.

Memtester can be executed as a user space program but it can not test 
the space reserved by the kernel.
Considering how small the space reserved by the kernel, it's still a 
worthy solution, but it will still take a lot of memory (if you want to 
test as many memory as possible).

For the timing:

If installing new ram, always run a memtest.
If overcloking/changing DIMM timming, always run a memtest.


Finally, backup is always recommended, no matter what.


> Is there any BTRFS tool, perhaps to run 
> periodically, that can help me detect bad ram hence mitigate the 
> consequences? There is a webpage called 'Will ZFS and non-ECC RAM kill 
> your data?' where it's suggested that ZFS scrub effectively detects bad 
> ram

I doubt, because bad ram can easily corrupt your metadata/data, and the 
same bad content is written to disk.

Furthermore the checksum will still match (calculated using the bad 
metadata/data), thus it's impossible to detect no matter what.


And bad RAM can happen at any random byte, if it's some core kernel 
structure, you're doomed anyway.

> (when at least two copies of the same file and/or metadata are 
> stored, and I wonder if there are other assumptions here...), but I'm 
> new to btrfs and I wonder if the reasoning can be applied to btrfs as 
> well, and how effective of a mitigation it would actually provide. OS is 
> GNU (Guix) and I think can't use ECC because I suspect my X200 
> motherboards wouldn't support it?
> 
> Please CC: or BCC: me cause I'm not subscribed.
>