SSD drives

Juan Orti Alcaine j.orti.alcaine at
Sat May 26 13:53:49 UTC 2012

2012/5/24 Michal Schmidt <mschmidt at>:
> On 05/24/2012 03:20 PM, Gerry Reno wrote:
>> So is F17 going to support TRIM w/LUKS automatically?
>> Or do we need to perform some special configuration to get TRIM
>> w/LUKS?  (Yes, I understand some attacker might be able to guess my
>> filesystem type due to erased blocks - seems very low risk though).
> To use this feature, you can specify the option "allow-discards" in
> /etc/crypttab. You need systemd >= 44-11, currently in updates-testing.
> Michal

I have updated to systemd-44-12 to test this functionality, but I
don't know if I'm doing it right. I have read that LVM has added
support for passing discards to the layer below. Currently I have:

Partition -> Luks -> LVM -> ext4

ext4 is mounted with discard. I haven't done anything to LVM, and in
/etc/crypttab I have added "allow-discards" as the fourth column.

I suspect it isn't working because "cryptsetup status
/dev/mapper/luks-uuid" does not say anything about discards. I think
it must say "flags: discards"

Any suggestion?

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