Recently has been added support for passing TRIM requests through Luks to the block device, but dracut does not honor this option in crypttab. The versions needed are: kernel >= 3.1, cryptsetup >= 1.4.0 and systemd >= 44-11
This is my crypttab:
luks-1234567890-3bbc-5444-b1c9-1234567890 UUID=1234567890-3bbc-5444-b1c9-1234567890 none allow-discards
I have found a quick and dirty solution in this post:
dracut-018-65.git20120612.fc17 has been submitted as an update for Fedora 17.
dracut-018-78.git20120622.fc17 has been submitted as an update for Fedora 17.
* should fix your issue,
* was pushed to the Fedora 17 testing repository,
* should be available at your local mirror within two days.
Update it with:
# su -c 'yum update --enablerepo=updates-testing dracut-018-78.git20120622.fc17'
as soon as you are able to.
Please go to the following url:
then log in and leave karma (feedback).
dracut-018-78.git20120622.fc17 has been pushed to the Fedora 17 stable repository. If problems still persist, please make note of it in this bug report.