Mailinglist Archive: opensuse-support (155 mails)

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Re: [opensuse-support] Trimming on encrypted partitions
On 10/03/2019 12.49, Oleksii Vilchanskyi wrote:
On 2/28/19 2:06 PM, Carlos E. R. wrote:
Check your mount options. If you use LVM or encryption, things change, too.

For example:

Isengard:~ # fstrim -av
/: 376 MiB (394194944 bytes) trimmed

/home doesn't appear, it is encrypted.

Thanks for that, turns out the trimming wasn't working for my encrypted
partitions under LVM when I decided to check it.

Which is because I forgot to add the option "allow_discards" to
/etc/crypttab, and I did not reboot the machine since I did.

discard is still not working on my home. I changed /etc/crypttab on the
28/2 and rebooted six days ago:

cr_home /dev/disk/by-id/ata-KINGSTON_...-part5 none

But the log says:

<3.4> 2019-03-04T00:21:10.823356+01:00 Isengard systemd-cryptsetup 596 -
- Encountered unknown /etc/crypttab option 'allow_discards', ignoring.

Looking on man, it says:

Allow discard requests to be passed through the encrypted
block device. This improves performance on SSD storage but has security

So, wrong syntax. Changing again, and scheduling another reboot.

Googling, I see that "--allow-discards" is an option for "cryptsetup"
command. Some posts mention that "allow_discards" exist somewhere in the

The confusion could come from commands like "dmsetup table --showkeys"
that show "allow_discards" if enabled.

Cheers / Saludos,

Carlos E. R.
(from 15.0 x86_64 at Telcontar)

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