On 04/01/2018 03:06 PM, 'awokd' via qubes-users wrote:
On Sun, April 1, 2018 6:15 pm, cooloutac wrote:
Doesn't using trim on encrypted drive lessen security though?
In my opinion, it's so marginal a security decrease it hardly bears
mention. :) There's a link in the trim doc for further reading.
I'd like to remind people: Discard and TRIM are not exactly the same thing.
Commands like 'fstrim' only generate discards, and in a Qubes LVM setup
those discards will logically deallocate blocks in the pool, thus
freeing up space for filesystems.
If you enable 'discard' or 'disktrim' or whatever they call it these
days in crypttab, that will result in discards being converted into
hardware TRIM commands. That is because the crypto layer is the one
closest to the hardware in our configuration.
Does TRIM free up space? No. It helps the SSD maintain top write speeds
and perform more efficient wear-leveling. On some drives, it will also
cause the unallocated data to be wiped-out (according to vendor claims).
Does fstrim free up space? Yes! Because it actually generates discards
and the name is misleading.
IMO, the best thing to do is edit your dom0 /etc/fstab and add 'discard'
to the options for root fs '/'. That will free up space in a usable way
and you won't need to run fstrim.
--
Chris Laprise, tas...@posteo.net
https://github.com/tasket
https://twitter.com/ttaskett
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