Discard is not working, discard doesn't free up space

[wdmarket]

Hi.
So I added new SSD. 2TB NVMe.
I did move some VMs to this SSD, I need free up space. at this moment proxmomx shows full VMs disk full size in admin panel
So I did enable dsicard on, than did login in Ubuntu 20.04 guest and did run trim commands.
But proxmox panel is showing there is no space on disk enough.
When I run zpool list, I see different values, which could more true with space.
Like here is picture about where free space for disk 1.37 tb.

 

[smueller]

Hi,
for Discard to work you need to use LVM-Thin as Disk-Type and TRIM your Filesystem in the OS

(You need block storage https://pve.proxmox.com/wiki/Storage )

 

[wdmarket]

T

Hi,
for Discard to work you need to use LVM-Thin as Disk-Type and TRIM your Filesystem in the OS

(You need block storage https://pve.proxmox.com/wiki/Storage )

thanks, i did these steps on zfs.
I am hosting stores on it, zfs seems more relaible.
Is it somehow possible to do on zfs?

 

[smueller]

It works with ZFS,
just add the Volume as LVM-Thin, not as LVM or Directory.

If you need further help, I'll make you a small Tutorial

 

[smueller]

I was wrong:

1. Create your ZFS Pool: Do not add as Storage yet
2. Go to Datacenter -> Storage -> Add -> ZFS
3. Select your ZFS Volume and select Thin provision

Or with your existing ZFS go to Step 2 and 3

 

[wdmarket]

I was wrong:

1. Create your ZFS Pool: Do not add as Storage yet
2. Go to Datacenter -> Storage -> Add -> ZFS
3. Select your ZFS Volume and select Thin provision

Or with your existing ZFS go to Step 2 and 3

View attachment 75309

Yes, thank You very much.
This is what I needed!

 

[vawaver]

Hello,

I’m facing a similar issue as described in this thread. I have a VM with Ubuntu Server 24.04 on Proxmox 8.3.1. After deleting a large amount of data in the VM (from approximately 1 TB down to ~300 GB), I expected the free space to be released on the ZFS level. However, the backup size still remains the same (~1 TB).

I’m attaching a screenshot of my ZFS pool settings:


My questions:

• Are my ZFS pool settings correct?
• If they are, how can I manually or automatically perform space reclamation so that Proxmox recognizes the freed space, and the backup size reflects the actual used space?

 

[smueller]

Hi @vawaver

could you please share your VM Configuration?

Did you enable "Discard" in the Disk?

 

[vawaver]

Hi @smueller
There is my configuration for the disk (it is NVME type)

 

[smueller]

Try fstrim in the VM

Reference PVE-Docs: https://pve.proxmox.com/pve-docs/pve-admin-guide.html#_trim_discard

 

[smueller]

Edit: You can also run the service manually with systemctl start fstrim.service

The fstrim Service runs Weekly by default.

 

[vawaver]

@smueller
I am very glad for your answers. Unfortunately I am not IT pro or a programmer so I want to solve this issue as simple as possible.
That is why I ask numb questions.
I read the admin guide but I did not find any helpful information.

So if I understand it right I can connect to my VM via ssh and run:

sudo fstrim -av

Is it correct or you recommend something else?

 

[vawaver]

I miss your previous answer about using command

systemctl start fstrim.service

I tried it and gonna make a Proxmox backup for testing.
Then I will let you know.

 

[smueller]

It's correct and should work with out issues.

you should get something like this as output:

But you would have to run it periodically.

Or set up a cron job to run fstrim weekly or for example every 2 days, follow these steps:

1. Open the crontab editor
   Run the following command in your terminal:
   

   crontab -e

   
   
2. Add the cron job for fstrim
   Insert the following line into the crontab file:
   Weekly:
   

   @weekly /sbin/fstrim -a

   
   Every two days:
   

   0 3 */2 * * /sbin/fstrim -a

   
   
3. Save and exit
   After editing the crontab file, save the changes and exit (in vim, press Esc, type :wq, and hit Enter).
   
   
4. Verify the crontab entry
   To confirm the cron job is set, list the crontab entries:
   

   crontab -l

 

[vawaver]

@smueller
Perfect!
I just tested a Proxmox backup of trimmed VM and it finally works as I need!!!
I appreciate your help.

Now I am able to create Wiki tutorial for my friends for this topic.