fstrim and Luks / dm-raid

[Erwan David <erwan@rail.eu.org>]

Hi,

I've got a computer with 3 SSD in RAID5 (dm-raid) containing a LUKS
partition, then a lvm

Is fstrim useful in suc a case ? Or on mylaptop without the raid, but
with LUKS and LVM ?

Should I add the discard option in fstab ? Or an equivalent in
mdadm.conf or cryptsetup.conf ?

Thanks