On 15/01/2023 16:01, Reindl Harald wrote:

there are more important things like keep the idiotic 
"/sys/block/md0/md/mismatch_cnt" at 0 and until that isn't solveable 
after decades don't risk my data with advanced experiments

however, that's all not part of the topic "What does TRIM/discard in 
RAID do"

Except - may I suggest you go back and read your very first reply to the 
OP - "trim makes no sense in the raid layer". YOU said, in effect, "it's 
not implemented because there's no point".

This whole drift away from the subject was sparked by that comment - 
your comment - when in fact trim DOES make a lot of sense. It's a shame 
it isn't implemented.

Cheers,
Wol