21.01.2019 22:00, Carlos E. R. пишет:
All drivers involved in request processing must support and allow discard requests. This is exactly what "allow_discard" dm-crypt option does; so even though your physical devices claim to support discards (using whatever dialect they speak) those requests will be ignored by crypto-container and never reach your physical device.
Your encrypted devices (or better underlying physical devices) are never trimmed unless you explicitly allow it.
Let me see if I understood. On an encrypted partition, if /etc/crypttab has "allow_discards", trim will happen when the trim cronjob runs, or online via option in fstab.
Yes if all other involved drivers also allow it (this thread mentioned LVM2 as example). If you use filesystem on LUKS on physical device directly it should be enough.