Am Mon, 06 Nov 2017 14:28:32 +0100 schrieb Christian Seiler: > But all that doesn't really help you if the underlying LUKS container > isn't opened with the discard option set. And as far as I know there is > no possibility of tagging a LUKS container with that option, you must > always supply that option to the cryptsetup command (which is done > implicitly via /etc/crypttab).
Thanks for your detailed and extensive answer. That's exactly the answer I was afraid of. ;-) So I will add an entry to the /etc/crypttab and hope that fstrim will do it's job. All system without a modified crypttab should mount the device but fstrim will fail. I think I can live with that solution. > You could ask the LUKS developers to include an additional flag in their > headers that allows you to specify that this volume should be opened > with discards allowed by default That is a good idea. I think I will write an ticket for that. Thanks again.