Arch Linux

netpumber

Member

Registered: 2009-09-20

Posts: 134

LVM + LUKS + TRIM @ root partition

Hi.

I'm installing a fresh arch linux PC right now with LVM + LUKS and TRIM because i have one SSD , and UEFI mobo.

SSD has a physical partition for the /boot and the rest one used with LVM where a virtual group created called "lvmRootPool" which contains two logical volumes ("lvmRootPool-root" and "lvmRootPool-swap")

The lvmRootPool-swap was kept for swap and
the lvmRootPool-root for /.

Here comes the question. I want to enable TRIM for that disk (i know the security risk) and following this guide i have to add a specific line with discard keyword in /mnt/etc/crypttab (i'm before chroot). But when i open the /mnt/etc/crypttab it has a note saying

Do not list your root partition here, it must be set up beforehand by the initramfs (/etc/mkinitcpio.conf)

So what i supposed to do ? Should i add that line at crypttab file or not ?

lvmRootPool-root          /dev/sda2          none             luks,discard

Also , is it possible to use TRIM for swap ? I think that isn't but maybe something have been changed that i don't know.

Thank you.

Last edited by netpumber (2015-05-24 18:06:40)

qinohe

Member

From: Netherlands

Registered: 2012-06-20

Posts: 1,498

Re: LVM + LUKS + TRIM @ root partition

My advice is to use the Arch wiki, guides from elsewhere are not really honored, here.
You didn't setup your mkinitcpio properly is what this line suggests.

Yes, you can in fact use trim on a swap partition using discard.

A few links that might be relevant:
https://wiki.archlinux.org/index.php/Dm … _.28SSD.29

Read the note:
https://wiki.archlinux.org/index.php/Sw … _partition

satchmosgroove

Member

From: Long Beach, NY

Registered: 2010-01-13

Posts: 88

Re: LVM + LUKS + TRIM @ root partition

maybe your missing pieces are: https://wiki.archlinux.org/index.php/So … IM_for_LVM and https://wiki.archlinux.org/index.php/Dm … encryption

In a nutshell:
For encryption you need to change the kernel parameter in your bootloader, add encryption and resume hook to mkinitcpio.conf. If the hooks are at the right spots, it just works for swap as well.
For LVM passthru there is a setting described in the link above
You still need the discard flags in your fstab.