Server-Disk IO delay 100% when cloning VM templates on LVM thin datastore

[LSX3]

Hello everyone,

I am experiencing a reproducible issue with Proxmox VE 9.0. After a fresh installation, I am using the default LVM-Thin datastore that PVE creates during setup.

Whenever I create a full clone from a VM template (disk format is raw), the I/O delay immediately spikes to 100%. As a result, other running VMs freeze completely and no longer respond. Even the QEMU guest agent does not respond anymore. The only way to recover is to issue a Stop command on the affected VMs.

Steps to reproduce:

1. Fresh install of PVE 9.0
2. Keep the default LVM-Thin datastore
3. Create a VM template
4. Perform a full clone from the template (disk = raw)
5. I/O delay spikes to 100% → other VMs freeze → only “Stop” helps

Additional notes:

• The problem occurs on multiple reinstalled hosts, always the same result.
• No special configuration changes were made to storage or VMs.
• Using full clone, not linked clone.
• Disk format = raw.

Has anyone else seen this behavior on PVE 9.0 with LVM-Thin?

Any suggestions or workarounds would be greatly appreciated.

Thanks in advance!

 

[Impact]

Please share lsblk -o+FSTYPE,MODEL. I want to see what kind of disks you're using.

 

[LSX3]

NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINTS
sda 8:0 1 0B 0 disk
sdb 8:16 0 22.4T 0 disk
├─sdb1 8:17 0 1007K 0 part
├─sdb2 8:18 0 1G 0 part /boot/efi
└─sdb3 8:19 0 22.4T 0 part
├─pve-swap 252:0 0 8G 0 lvm [SWAP]
├─pve-root 252:1 0 200G 0 lvm /
├─pve-data_tmeta 252:2 0 15.9G 0 lvm
│ └─pve-data-tpool 252:4 0 22.1T 0 lvm
│ ├─pve-data 252:5 0 22.1T 1 lvm
└─pve-data_tdata 252:3 0 22.1T 0 lvm
└─pve-data-tpool 252:4 0 22.1T 0 lvm
├─pve-data 252:5 0 22.1T 1 lvm

 

[Impact]

Hmm, no proper model shown. Judging from the size and name I assume this is some kind of RAID or fake RAID? Can you check the model number of the drive(s) and what kind of RAID it is?

 

[LSX3]

Hmm, no proper model shown. Judging from the size and name I assume this is some kind of RAID or fake RAID? Can you check the model number of the drive(s) and what kind of RAID it is?

Yes, this is an HP ML350 Gen10
It is equipped with an HP Smart Array P408i-a SR Gen10 RAID controller (2GB cache, 8-port modular, RAID levels 0, 1, 10, 5, 50, 6, 60, HBA mode, including BBU)
There are 8 enterprise SSDs installed, configured as a RAID6
The RAID controller provides the RAID6 volume, which is used by PVE as the datastore