Arch Linux

emacsomancer

Member

Registered: 2014-09-20

Posts: 211

encrypted ssds & trim (& zfs) ?

If I understand the wiki ( https://wiki.archlinux.org/index.php/Dm … _.28SSD.29 ) right, if I want to enable trim for a luks encrypted ssd, I should:

1. add allow-discards to the cryptdevice in the options section of bootloader entry

2. also add rd.luks.options=discard in the options section of the bootloader entry

3. also add discard to the options section of the relevant drive/partition in /etc/fstab

is this correct

For a luks encrypted ssd that has a zfs filesystem inside it, can I enable trim in the same fashion?  Should I not enable trim in this case?  Does it matter what filesystems are contained within a luks encrypted drive with respect to trim?

Last edited by emacsomancer (2017-03-24 04:47:15)

blahhumbug

Member

Registered: 2016-10-08

Posts: 64

Re: encrypted ssds & trim (& zfs) ?

ZFS and SSDs are not yet ready for trim.  The following PR (which is being replaced with a new PR) is tracking the progress of trim support in ZoL.

https://github.com/zfsonlinux/zfs/pull/3656

EdIt:  Also, if your SSD is an NVMe SSD then you should not use discard.  https://wiki.archlinux.org/index.php/So … e#Discards

Last edited by blahhumbug (2017-03-24 05:14:51)

emacsomancer

Member

Registered: 2014-09-20

Posts: 211

Re: encrypted ssds & trim (& zfs) ?

ZFS and SSDs are not yet ready for trim.  The following PR (which is being replaced with a new PR) is tracking the progress of trim support in ZoL.

https://github.com/zfsonlinux/zfs/pull/3656

EdIt:  Also, if your SSD is an NVMe SSD then you should not use discard.  https://wiki.archlinux.org/index.php/So … e#Discards

So it doesn't matter whether  ZFS is inside of an encrypted luks "container" or not?

(Also, can anyone comment on whether I'm on track for trim on non-zfs-containing encrypted ssd?)

blahhumbug

Member

Registered: 2016-10-08

Posts: 64

Re: encrypted ssds & trim (& zfs) ?

I honestly am not sure of the correct answer here.   I'm also using luks with dm-crypt and ZFS, but have been waiting for the ZoL PR to finish before messing with trim.