Proxmox showing incorrect disk usage

[powersupport]

We have a single-node Proxmox setup with one VM, which is a Proxmox Backup Server.

The node has a total storage capacity of 20 TB, of which 14 TB is allocated to the VM. Currently, the VM has used 6 TB of storage, leaving about 8 TB available within the VM. However, Proxmox VE is showing a total usage of 18.93 TB out of 20 TB. the disk configured with btrfs

I’m not sure where the remaining storage has gone. Does anyone have any insights?

 

[dcsapak]

can you show where you get these number (e.g. the commands + output or screenshots) ?

also do you maybe have snapshots on the vm ? (that + data written will consume more disk space than the disks ofcourse)

did you maybe do backups on the same disks?

 

[Fantu]

Can be useful post also the output of

btrfs fi usage

.
You have to be careful and manage well when using snapshots because it is easy to underestimate the space issue (unless you use temporary snapshots or ones kept for a very short time).

 

[Impact]

You might also be lacking Discard.

 

[powersupport]

HI,
We have thoroughly checked and confirmed that no backup snapshots are stored in the storage. There is only one VM, which is using 6 TB, but the remaining usage is still unexplained.


btrfs fi usage /
Overall:
Device size: 18.19TiB
Device allocated: 18.18TiB
Device unallocated: 5.00GiB
Device missing: 0.00B
Device slack: 7.00KiB
Used: 17.24TiB
Free (estimated): 966.43GiB (min: 966.43GiB)
Free (statfs, df): 966.42GiB
Data ratio: 1.00
Metadata ratio: 1.00
Global reserve: 512.00MiB (used: 0.00B)
Multiple profiles: no

Data,RAID0: Size:18.16TiB, Used:17.22TiB (94.83%)
/dev/sda3 9.08TiB
/dev/sdb3 9.08TiB

Metadata,RAID0: Size:26.00GiB, Used:20.90GiB (80.38%)
/dev/sda3 13.00GiB
/dev/sdb3 13.00GiB

System,RAID0: Size:16.00MiB, Used:1.27MiB (7.91%)
/dev/sda3 8.00MiB
/dev/sdb3 8.00MiB

Unallocated:
/dev/sda3 2.50GiB
/dev/sdb3 2.50GiB

 

[Fantu]

The non -allocated space is dangerously low (only 5GB), the difference with the free one can be resolved with a balance, it would be better first to delete something in order to free space, the screenshots you posted do not make it clear about what it can be.
After for the balance I suggest do before on chunk with allocation <=10%:
btrfs balance start -v -dusage=10 /
and after up to 50%:
btrfs balance start -v -dusage=50 /
can require big time if done on big size on hdd like I suppose are they.
In any case, the maximum free space is actually not much and there is certainly something that does not consider itself well (in most cases they are snapshots)
A strange thing I saw from partial vm config is presence of virtio scsi single controller but disk setted as sata, why?

Edit:
from what you wrote:

We have thoroughly checked and confirmed that no backup snapshots are stored in the storage. There is only one VM

With only that vm with 13TB raw (from the little is visible from these screenshot) do not come back and there is certainly anything else, sure that there are no snapshot BTRFS? There are no other big files in the root or storage (are in the same btrfs volume)?
In the storage on all the other parts outside the VM disk are really empty? You should also check any things done outside the Proxmox console and not visible in it
If there is no btrfs snapshot this should list nothing:

btrfs subvolume list -s /

and not other things, this should only have the size of the vm disk in /var/lib/pve/local-btrfs/images

du -h -d 3 /var/lib/pve/local-btrfs/

 

[powersupport]

HI,

THere is nothing to delete, confirmed everything.