On 15/01/2023 at 13:13, Reindl Harald wrote:

Am 15.01.23 um 13:00 schrieb Pascal Hambourg:

quoted

Linux RAID supports TRIM/discard, but what does it do exactly ?
Does it only pass-through TRIM/discard information to the underlying 
devices or can it also store information about which blocks contain 
valid data in the superblock metadata?

pass-through TRIM/discard

it makes no sense to store that on the RAID layer

Wouldn't it make sense to:
- skip the initial sync at array creation
- only resync valid data areas during array resync
- reduce wear caused by useless writes on flash drives
- enable TRIM/discard with parity RAID levels by default without relying 
on the underlying device capability to return zeroes on read after TRIM
- ignore mismatches in invalid data areas when scrubbing
?