[SOLVED] Activate fstrim inside a VM without discard checked : Will it break something ?

[cryonie]

Hello,

The question is really what the title says
If I activate trim function inside my VM (debian) without discard checked on the VM disk, will it break something in my VM or on my host ?
Or will it just do nothing (not the TRIM at least and not break something) ?

Thank you
Cryonie

 

[mira]

No, it won't break anything.
It just won't do anything.

 

[cryonie]

Thank you very much

 

[Docop2]

Humm it was clear, but i re-read and i'm confused..
With the discard option : on , this means we don't have to run fstrim inside the vm ?

 

[Dunuin]

Humm it was clear, but i re-read and i'm confused..
With the discard option : on , this means we don't have to run fstrim inside the vm ?

You have to do both in order for discard to work. And you additionally need to use a protocol like "virtio SCSI" that supports TRIM and and not "IDE" or "virtio block".

 

[LnxBil]

You have to do both in order for discard to work. And you additionally need to use a protocol like "virtio SCSI" that supports TRIM and and not "IDE" or "virtio block".

.. and the backend storage needs to support it. Just because you checked everything and ran fstrim does not mean that it is actually discarded properly.

This can easily be checked by running your fstrim stuff and backup your machine, then fill the empty space with zeros (e.g. dd if=/dev/zero ...) and backup again.

 

[Docop2]

Just to confirm what operation you do exactly ? On Proxmox itself, the fstrim timer is enable and did run every week.
Like over a new xubuntu vm install, it also have the fstrim timer 1 per week enable.
But with running: lsblk -D = that show all 0 , witch is supposed to be different number for a support ..

Also I haven't seen much different with the vm option 'ssd enable'